text:
An improved method and apparatus for drying a natural gas stream such as water containing natural gas introduces triethylene glycol into a high speed gas stream at a pressure in excess of that of the gas stream to achieve a drying effect by impaction and rapid expansion and turbulence in a mixing zone. The triethylene glycol and water are removed by a centrifugal separator.
1. In an apparatus for drying a natural gas stream comprising interconnecting tubular members defining a generally horizontally extending continuous fluid flow path and a centrifugal separator tangentially connected at one end thereof, the improvement comprising an adapter conduit fluidly connected to one tubular member and having a first inner diameter at one end thereof, a nozzle chamber connected to said adapter at said first inner diameter, said nozzle chamber being adjacent the other end of said interconnected tubular members and means for introducing gas to be dried into said adapter conduit via said other end of said tubular members, a nozzle block removably positioned in said nozzle chamber and having a jet forming opening centrally thereof, said jet forming opening being connected directly to said adapter conduit and having a uniform inner diameter which is substantially smaller than said adapter conduit first inner diameter to define an orifice-like opening into which fluid from said adapter passes, said jet forming opening having an annular passageway separated therefrom, a diverging conduit fluidly connected to said orifice-like opening to receive fluid therefrom, and a plurality of individual nozzles positioned circumferentially in said nozzle block diverging conduit downstream of said orifice-like opening and communicating with said annular passageway, said nozzles being oriented to inject fluid into fluid flowing out of said orifice-like opening directed downstream toward an extension of an axial center line of said orifice-like opening, said nozzle block disposed in said nozzle chamber, an adjacent downstream portion of said interconnecting tubular members defining a mixing chamber which is fluidly connected to said diverging conduit and has an internal diameter essentially equal to the largest portion of said diverging conduit so that the area of said mixing chamber is substantially greater than the area of said orifice-like opening and means for supplying triethylene glycol under pressure greater than said gas stream to said annular passageway in said nozzle block for injection by said individual nozzles into the gas stream leaving said orifice-like opening.
2. The apparatus for drying a natural gas stream set forth in claim 1 and wherein the jet forming opening extends through the nozzle block at an apex of said diverging conduit.
3. The apparatus for drying a natural gas stream set forth in claim 1 and wherein said interconnecting tubular members are detachably connected to one another in the area thereof defining said nozzle chamber.
4. The apparatus for drying a natural gas stream set forth in claim 1 and wherein said means for supplying triethylene glycol to said annular chamber in said nozzle block comprises a pump and a glycol stripping station in communication with said annular chamber and said centrifugal separator.
5. The apparatus for drying a natural gas stream set forth in claim 1 and wherein said annular passageway has a portion thereof defining a conical chamber through which said gas stream is directed by said jet opening and wherein said individual nozzles are located in said portion forming said conical chamber.
(1) Field of the Invention
This invention relates to drying natural gas by removing water and/or sulfur compounds from wells, transmission lines, gathering stations, and the like.
(2) Description of the Prior Art
Apparatus and methods heretofore used for drying natural gas are generally concerned with the exposure of the moisture carrying gas to trays of glycol such as illustrated for example in U.S. Pat. No. 4,070,231.
Similar devices are found in U.S. Pat. No. 3,664,091 and are referred to in U.S. Pat. Nos. 3,864,103 and 4,010,009.
A somewhat different device for removing water from natural gas may be seen in U.S. Pat. No. 3,322,411 wherein a generally horizontally disposed fluid flow passage is filled with a porous material, wet gases directed therethrough and glycol is introduced at intervals therealong.
The prior art devices are usually of fixed design and related in size to the particular flow volume of a gas well and the prior art units are generally unable to remove water and contaminants from the gas stream beyond the point of equlibrium in that they cannot remove more water than the glycol is able to absorb.
The present invention will remove water beyond the point of equilibrium due to the injection of the triethylene glycol into the high speed gas stream and the arrangement which permits an expansion in a turbulent flow in a mixing zone with the resulting extremely high surface to mass ratio and a resulting high degree of interpenetration of water and glycol.
Additionally the apparatus and method result in the cooling of the gas stream in a refrigeration and change of pressure effect, all of which contribute to a superior drying action.
The present method and apparatus can be varied to match various flow volumes and pressures by merely changing the triethylene glycol injection nozzles thus rendering the invention readily adaptable to many situations.
An apparatus and a method for drying a natural gas stream is disclosed which directs the wet natural gas through a nozzle to form a jet stream and introduces triethylene glycol into the jet stream at a pressure in excess thereof and provides for a turbulent flow in a mixing zone which also permits rapid expansion so that the fluids are divided into many tiny particles with an extremely high surface to mass ratio so as to provide a high degree of interpenetration of the water and triethylene glycol. The triethylene glycol collects water upon contact and the considerably greater contact realized with the present apparatus and method results in an extremely high efficiency. The fluid mixture leaves the mixing zone and the water glycol mixture is spun out in a centrifugal spin chamber with the water and glycol mixture being removed at the bottom of the separator. The glycol water mixture is subsequently fed through a standard glycol regenerating (stripping) station where the glycol is stripped of the water and returned to the process and apparatus and the water drained away.
FIG. 1 is a diagrammatic view of the improved apparatus of the invention;
FIG. 2 is an enlarged cross sectional detail of a portion of the apparatus seen in FIG. 1 with parts broken away;
FIG. 3 is an enlarged detail of a centrifugal separator seen in FIG. 1 of the drawings with parts broken away and parts in cross section;
FIG. 4 is an enlarged detail in vertical section showing a glycol injecting nozzle used in the apparatus illustrated in FIGS. 1 and 2;
FIG. 5 is a plan view of the glycol injecting nozzle seen in FIG. 4; and
FIG. 6 is a cross sectional detail on lines 6--6 of FIG. 3.
In the form of the invention chosen for illustration and description herein, the apparatus and method for drying a natural gas stream is best seen in FIG. 1 of the drawings which is a diagrammatic disclosure in which natural gas from a well or collecting main is introduced into the device at the left thereof as indicated by the arrow and the letter G. The introduction is by way of an adaptor 10, one end of which is engaged in a coupling 11 by which communication is established with the natural gas supply line and the other end is flanged at 12 and secured to a flange 13 on a tubular mixing member 14.
In FIG. 2 of the drawings, the adaptor 10 and the tubular mixing member 14 are shown with the flanges 12 and 13 secured to one another by bolt and nut fasteners 15 and it will be observed that the configuration of the flanged ends 12 and 13 is such that a nozzle chamber 16 is defined therebetween. The nozzle 17 in FIGS. 4 and 5 of the drawings is normally positioned in the nozzle chamber 16.
By again referring to FIG. 1 of the drawings, it will be seen that the opposite end of the tubular mixing member 14 with respect to the flange 13 is flanged as at 18 and joined thereby to a flange 19 on a transition section 20 which is circular at its point of engagement with the flange 19 and oval at its opposite end 21 where it tangentially joins a centrifugal separator 22 as may be seen by referring to FIGS. 3 and 6 of the drawings.
In FIG. 3 of the drawings, the water and glycol are separated from the natural gas by the cyclone created by the centrifugal spin due to the tangential introduction of the fluids thereinto, the dry gas flows outwardly upwardly through the open upper end 23 of the centrifugal separator 22 and the glycol and water flow downwardly and out of the centrifugal separator 22 by way of a drain line 24.
By referring again to FIG. 1 of the drawings, it will be seen that the drain line 24 communicates with a conventional stripping station 25 as known in the art in which the glycol is separated from the water and delivered to a tube 26 which communicates with a pump 27 which in turn communicates with the glycol injecting nozzle 17 by way of a tube 28. The water leaves the stripping station by a drain line 29.
As heretofore mentioned, the injection of the triethylene glycol into the jet stream of natural gas is occasioned by a nozzle assembly 17 which is normally disposed in the nozzle chamber 16 as best seen in FIG. 2 of the drawings. The nozzle assembly is illustrated in enlarged detail in FIGS. 4 and 5 of the drawings and by referring thereto it will be seen that the nozzle assembly body 17 has an annular chamber 30 therein which surrounds a jet forming opening 31 through which the natural gas to be dried is directed. The jet forming opening 31 is of substantially smaller diameter than the internal diameter of said adaptor 10. The downstream end of the jet opening 31 communicates with a conical chamber 32 and a plurality of individual glycol injection nozzles 33 are arranged in a circumferential pattern in the conical chamber 32 so as to communicate with the annular chamber 30 hereinbefore described. A drilled and tapped opening 34 communicates with the annular chamber 30 and with the tube 28 as seen in FIG. 1 of the drawings so that dry triethylene glycol delivered by the pump 27 through the tube 28 will be supplied in suitable volume and at a pressure in excess of the pressure of the natural gas emerging from the jet opening 31 and thereby delivered into the jet stream of the natural gas so as to cause a turbulent mixing action therein. If necessary more than one of the drilled and tapped openings 34 are provided so as to insure an adequate supply of glycol to the device.
In FIG. 5 of the drawings, the circumferential arrangement of the individual glycol injecting nozzles 33 will be seen and it will be observed that the nozzles 33 are positioned at uniform angles from the horizontal center line of the jet opening 31 and so that the triethylene glycol introduced through the relatively small openings of the individual glycol nozzles 33 will impinge in and intermix in the gas stream in the tubular mixing member 14 and that portion thereof surrounded by the flange 13 as heretofore referred to.
It will thus be seen that the apparatus and method disclosed herein for drying a natural gas stream uses chemicals plus pressure and cooling in a synergistic effect with the inter-reacting forces acting effectively due to the re-expansion of the fluids in the mixing member 14 and the simultaneous tubulent flow generated by the rapid expansion and the resulting high degree of interpenetration and cooling at the point of mixing which results in an extremely efficient water removal.
As will be understood by those skilled in the art, the triethylene glycol collects water upon contact and thus the greater the contact the higher the collection efficiency. The gas jet created and controlled in the apparatus and upon which the method depends, provides sufficient energy for the centrifugal separation of the water and glycol from the gas in the centrifugal separator 22 and the additional expansion area thereof slows down the gas stream and insures against its retention of any of the liquids, which as hereinbefore explained are drained away through the bottom of the centrifugal separator 22.
The method realized by the apparatus thus depends primarily upon the degree of atomization of the triethylene glycol, the high speed contact thereof, and the massive mixing of water and the triethylene glycol with the jet stream of natural gas, all as hereinbefore set forth.
Operating pressures of the gas stream can vary between 10 PSI and 2000 PSI and the apparatus adjusted for operation at different pressures by interchangeable nozzles 17, each having a different sized jet opening 31. The triethylene glycol is injected at substantially 15 PSI in excess of the pressure of the gas stream.
It will thus be seen that the method and apparatus for separating water from a natural gas stream as disclosed herein provide an efficient means which will operate in freezing weather, that may be readily adjusted to varying volume and pressure changes in the natural gas stream, and that the apparatus and method work under pressure whereas the prior art devices operate at atmospheric pressure.
Patent Citations
Referenced by
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Exceptional, 9.9
Our B & B is located in an area of 4000 m². All units are independent of each other. Rest and relaxation is prioriteir.Wij provide an extensive breakfast. Meals on request. The B & B is ideally located near a lively village Orba. For cyc...
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Featuring a terrace, Villa Empena is a villa, set in Orba. The property boasts views of the sea and is 28 km from Benidorm. Free private parking is available on site.The villa is composed of 2 bedrooms and 1 bathroom, equipped with a b...
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Located in the mountain town of Orba, Apartamentos Carrebaix offer apartments with free Wi-Fi and balconies with views of the valley.Each apartment with artisanal décor has a kitchen including an oven, microwave and coffee machine, and...
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Holiday home Urb.Rafol de Almunia offers pet-friendly accommodation in Orba. The property boasts views of the sea and is 32 km from Benidorm. Free private parking is available on site.The kitchen features a refrigerator and there is a ...
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Villa in Orba is a villa located in Orba and featuring a garden with a seasonal outdoor pool. The property is 26 km from Benidorm and features views of the sea.The villa is composed of 3 bedrooms and 2 bathrooms, equipped with a bath o...
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Situated in the small town of Orba, Le Reve features a private pool and a furnished terrace with views of the sea. Barbecue facilities are also available.Air-conditioned and heated, this house includes a lounge with flat-screen satelli...
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Featuring a private pool, La Casa Soleada is a Detached villa set in Orba. The property is 28 km from Benidorm and features views of the sea. Free private parking is available on site.Composed of 4 bedrooms and 3 bathrooms with bath an...
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heroes, heroes are hard to find, humor, fun, office, office humor, boss, chef, sports, romantics, love, men
This great custom product in white from our department Men and T-Shirt category can be printed just for you in the size and style you like. The design funny was created by funart and uploaded to Spreadshirt for you to have printed on a T-Shirt. Next to a host of other great customized designs, you can find this funny design in Spreadshirt's Office Humor category. If you are interested in topics like Fun or Heroes, then you'll love funny designs by funart. Spreadshirt also offers a huge selection of custom t-shirts, hoodies and accessories for the category Office Humor as well as top Humor clothing. funart's designs have already impressed many of our customers, so we are sure that we've got right stuff for you! Spreadshirt is your destination for great designs of all kinds – whether it's Fun, Heroes or Humor. We are sure that you will find something nice in our shop, there are many amazing custom Office Humor t-shirts, hoodies, or accessories for you to find! Tags: Design ID: 11947061
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text: http://forum.xda-developers.com – I was wondering does anyone know how to stop the phone from constantly changing signal type within a certain network setting? So if it finds moderate signal strength in one type it doesn't start aiming for the skies? So for instance you have your network setting on the 'any of 2/3/4G' option, you have a decent 4-bar 3g signal, and then it suddenly decides to go for glory and get a crappy/weak 4g signal and then keeps flipping back and forth! In the UK signal strength varies from street to street literally so it would be ideal to have the setting on 'any of 2/3/4G' with the phone attempting (HowTos)


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NEW YORK (AP) -That Andy Roddick's last match as a twentysomething would not be his last match at the 2012 U.S. Open was hardly in doubt Tuesday, especially whenever he was launching that intimidating, tough-to-handle serve of his.
He served a 141 mph (227 kph) ace to close the first set, a 134 mph (216 kph) ace to close the second and a 127 mph (204 kph) ace to finish off the third in Tuesday's 6-3, 6-4, 6-4 victory over 21-year-old American qualifier Rhyne Williams.
Even as Roddick's 30th birthday approaches on Thursday, even as his body has succumbed to injury after injury, his serve is pretty much still the same as it ever was. Now that he more frequently faces opponents who grew up cheering for him, Roddick knows more than ever he needs to rely on the best thing he's got, and 20 aces helped this time.
"You really don't see that shot," Williams said glowingly about Roddick's serve.
Heading into his Grand Slam debut, the 283rd-ranked Williams had one primary concern: "I was just hoping he wasn't going to go at me with a serve."
"I'm like, `Oh, no. Where's he going?' That's the first thing I thought of. Then it was, `It'll be great. I can play in front of a big crowd.' It was quite an experience," said Williams, a 12-year-old when Roddick won the U.S. Open in 2003.
That was the last Grand Slam singles title for an American man, the longest drought in history for a country that produced the likes of Pete Sampras, Andre Agassi, John McEnroe and Jimmy Connors (not to mention Bill Tilden or Don Budge).
Roddick found himself in an era dominated by Roger Federer and Rafael Nadal - and, more recently and to a lesser extent, Novak Djokovic, who began defense of his U.S. Open title by overwhelming 69th-ranked Paolo Lorenzi of Italy 6-1, 6-0, 6-1 on Tuesday - and while he never added a second major championship to his resume, he kept adapting his game to try to do just that.
Following Roddick into Arthur Ashe Stadium was 32-year-old Venus Williams, playing her first U.S. Open match since she pulled out before the second round in 2011 and revealed she'd been diagnosed with an autoimmune disease.
"Honestly, I didn't even understand what I was going through at that time last year. I feel like just this summer I've come to acceptance. Like it takes a long time to come to acceptance, especially when you're an athlete. You see yourself as this healthy person that nothing can defeat you," Venus Williams said. "So it takes a while before you can kind of see yourself as someone with flaws and chips in the armor. Now that I have come to accept it, it helps me a lot in how I need to prepare for my matches, the mindset I need to come into it."
After a shaky start, dropping the first two games - and even seven points in a row in one stretch - Venus Williams used her own powerful serve to right herself and beat Bethanie Mattek-Sands of the United States 6-3, 6-1. One serve at 124 mph (200 kph) jammed Mattek-Sands' left index finger, shoving it into a racket string so hard she needed attention from a trainer.
"She was crushing her serves," Mattek-Sands said. "I don't think anyone's returning those, so I'm not going to beat myself up too much."
Venus Williams won the 2000 and 2001 U.S. Opens, two of her seven career Grand Slam titles. That's half as many as her younger sister, Serena, who began her bid for No. 15 with a 6-1, 6-1 victory over 75th-ranked CoCo Vandeweghe in Tuesday's last match in Ashe, yet another all-American affair.
"Venus is amazing. She's the ultimate role model for me," Serena Williams said. "She's the ultimate fighter and champion - everything she's gone through and is going through. I have no excuses any more. She makes me a better person."
The younger Williams won the U.S. Open in 1999, 2002 and 2008, and is among the favorites in 2012 considering the way she dominated the competition recently while winning Wimbledon and a gold medal at the London Olympics.
"We need more American champions here to hold up these amazing trophies," Serena Williams said.
Three of the day's most notable upsets were turned in by young, up-and-coming Americans. In singles, 19-year-old Sloane Stephens, who is ranked 44th, eliminated 2010 French Open champion Francesca Schiavone 6-3, 6-4. And in doubles, 19-year-old Jack Sock and 22-year-old Steve Johnson knocked out the top-seeded team of Max Mirnyi of Belarus and Daniel Nestor of Canada 1-6, 7-6 (4), 6-2, while brothers Ryan and Christian Harrison defeated last year's runners-up, Mariusz Fyrstenberg and Marcin Matkowski of Poland 7-6 (3), 2-6, 7-6 (7).
One other exit of significance: 2009 runner-up Caroline Wozniacki, who began the year ranked No. 1 but has struggled and was seeded eighth, lost 6-2, 6-2 against 96th-ranked Irina-Camelia Begu of Romania. Bothered by a bad right knee, Wozniacki also lost in the first round at Wimbledon.
Appearing in his 13th consecutive U.S. Open - and wearing all-American sneakers for the occasion, replete with red and white stripes, and white stars on a blue background - Roddick sounded a willing to alter the expectations this time around. His own, and those of others.
Asked in an on-court interview what sort of present he would like in a couple of days, Roddick smiled and responded: "I just want to be around for next week. That's all I want for my birthday."
After a pause, he added: "And then we'll renegotiate."
Next up for Roddick is a second-round match against 19-year-old Bernard Tomic of Australia, who at last year's Wimbledon became the tournament's youngest quarterfinalist since Boris Becker.
Roddick, a former No. 1 who is seeded 20th at Flushing Meadows, is coy when it comes to questions about how much longer he can compete at the top of the game.
"I mean, I don't think you can ask him about retirement right now. I think as long as he's happy and he's playing well, I think he's going to keep playing," said 27th-seeded Sam Querrey of the United States, who beat Lu Yen-hsun of Taiwan 6-7 (4), 6-4, 6-4, 7-5.
Like Ryan Harrison, the 24-year-old Querrey is one of several younger Americans who have benefited from Roddick's advice and offers to train together in Austin, Texas.
Roddick extended that opportunity to Rhyne Williams after beating him Tuesday.
"He's kind of been the leader of American tennis amongst the guys for the last 10 years. He's been great. I mean, when I was 18, 19 - still to this day - he was always one of the first guys to invite me to Austin to practice," Querrey said. "He's always there for motivation. He's always there to tell you if you had a good win or to tell you, `Hey, step it up,' if you had a bad loss. He's really been a great mentor to everyone."
Follow Howard Fendrich on Twitter at http://twitter.com/HowardFendrich


text: Kansas City Royals Kansas City Royals Angels Astros Athletics Blue Jays Braves Brewers Cardinals Cubs Diamondbacks Dodgers Giants Indians Mariners Marlins Mets Nationals Orioles Padres Phillies Pirates Rangers Rays Reds Red Sox Rockies Royals Tigers Twins White Sox Yankees Home | Attendance | Charts/Graphs | Depth Chart | Directory | Roster | Schedule | Stats | MLB News | MLB Scores Career W-L67-70 Career ERA4.20 Name Jason VargasBorn 2/2/1983Height 6-0Weight 215Number 51Position SPBats LThrows LReg. SeasonPostseasonGame LogSplitsvs Battervs UmpireNotesSeasonWLERAGGSCGSHSVIPHRERHRBBSOWP2015 - KAN524.108800041.2452019511250Career67704.20 21219211601208.1123359556414935379214 SeasonWLERAGGSCGSHSVIPHRERHRBBSOWP2014 - KAN11103.713030110187.01978277194112812013 - ANA984.022424320150.01626867174610902012 - SEA14113.853333200217.12019493355514152011 - SEA10134.253232430201.020510595225913132010 - SEA9123.783131000192.21878681185411612009 - SEA364.91231400091.298535016245412007 - NYM0112.192200010.117141442412006 - MIA127.3312500043.05039359302522005 - MIA554.03171310073.2713433431590Last 10W/L/SERAIPHRERBBSOHR@ MIN 6/8W4.106.0500020vs. CLE 6/3W4.796.0822030@ NYY 5/26L5.164.0422161vs. CLE 5/5W5.266.0222251@ CLE 4/27W5.955.0322511vs. MIN 4/21 6.755.2855140@ MIN 4/16L6.003.01054111@ ANA 4/10W3.006.0522131 Notes:Selected by Marlins in 2nd round (68th) of 2004 draft; signed July 6, 2004. Traded to Ny Mets with Adam Bostick for Matt Lindstrom and Henry Owens; Nov. 20, 2006 Traded to Seattle in a three-team trade; Dec. 11, 2008 Traded to LA Angels for Kendrys Morales; Dec. 19, 2012 Signed with Kansas City to a four-year deal worth $32 million; Nov. 21, 2013 Highlights:


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Gov. Rick Perry To Appear For Processing Over Indictment
Friends of indicted Texas Governor Rick Perry are expected to rally outside the Austin Courthouse as he turns himself in for booking this afternoon.
Perry's Attorney Calls Indictment 'Banana Republic' Politics
"This is nothing more than banana republic politics," said Tony Buzbee, the lead attorney of the five lawyers Gov. Perry hired.
No Arrest Warrant Being Issued For Gov. Perry
A judge has decided not to issue an arrest warrant for Texas Gov. Rick Perry, a court official said Monday, meaning the Republican can continue traveling the country and gearing up for a possible 2016 presidential run despite being indicted on two felony counts of abuse of power.
Perry Moves Ahead With '16 Courtship Despite Case
Undeterred by indictment, Texas Gov. Rick Perry intends to travel to three major 2016 primary states during the next two weeks even as he faces the prospects of a highly unpresidential booking on felony charges.
Governor Perry Indicted For Coercion For Veto Threat
Governor Rick Perry has been indicted for abuse of power after carrying out a threat to veto funding for state public corruption prosecutors.
Accounting Expert: Feds' Case Against John Wiley Price Looks Solid
As a forensic accountant, Larry Kanter follows the money. He watches where it comes from and where it goes. From an accounting standpoint, Kanter says he's impressed with the 107-page indictment against Dallas County Commissioner John Wiley Price.
Dallas To Review Business Contracts Linked To Price Indictment
The CBS 11 I-Team uncovered the names of at least six companies referenced in the John Wiley Price indictment. Dallas city leaders are taking that list and reviewing their own contracts.
I-Team Reveals Businesses In Price Indictment
The names of the businesses involved in the John Wiley Price case were intentionally left off the indictment. Instead, they were given aliases like "Business A" or "Business B."
Fort Worth Officers Not Indicted For Killing Motorist
A North Texas grand jury has declined to indict three officers who shot and killed a 22-year-old man who they wanted to question about an earlier shooting.
High Court Rules On Emergency Request, A Year Later
Call it justice delayed. More than a year after the Dallas County District Attorney's office asked the Court of Criminal Appeals to step into the infamous contempt of court case, a ruling has come down.
Grand Jury Opts Not To Indict Dallas County Judge For Assault
A Dallas County grand jury has decided not to indict a state district judge on a felony charge of assault following a domestic disturbance with his girlfriend. Jurors made the decision Thursday in a case involving Judge Carlos Cortez.
Grand Jury Indicts Dallas Police Department Vice Detective
Federal prosecutors say a Dallas Police Department vice detective has been accused of passing unauthorized tips about police raids and investigations into prostitution.


text:
Thompsons Station Tutors
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Tutoring Anyone That Needs A Little Extra Help — Thompsons Station, TN
I have never been a formal tutor. I tutored fellow students while in high school. I was selected from teachers and given my contact information to parents of my fellow classmates. Also I served as a t...
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24 years old
Experienced Tutor, Reading, Math, Special Needs, Speech Language, Autism — Thompsons Station, TN
I provide tutorial services for anyone who has specific learning disabilities. I specialize in dyslexia, math disorders, reading, autism spectrum disorder, and individualized tutoring. I also provide ...
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Thompsons Station, TN
I can tutor most subjects for K-12 grades. I may have to brush up on Calculus and Science subjects though, so please be patient with me as I gather the information and research. I'll work with the stu...
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45 years old
College Student Looking For Summer Job — Thompsons Station, TN
I have babysat for my younger cousins on several occasions and have helped my mother with caring for my younger sister throughout the past several years. Two summers ago, I accompanied a family on the...
2 yrs of exp.
18 years old
Piano Lessons For Beginners — Thompsons Station, TN
First timers encouraged! Starting with the most basic concepts of piano, perfect for young children or others who cannot read music. Weekly lessons are $25 per half hour. Register now for Fall. Regi...
10 yrs of exp.
45 years old
Reading/Language Arts Tutor — Thompsons Station, TN
I am a former teacher with 10+ years of teaching experience. I have taught children in grades Pre-K through eighth grade.
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Part-Time English Tutor- Grades 7-12 — Thompsons Station, TN
I am a teacher in Williamson County Schools (certified in English/Language Arts grades 7-12). Whether your child needs to catch up, maintain skills, or work ahead, I can assist in his/her individual n...
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27 years old
Highly Qualified Certified & Licensed Teacher — Thompsons Station, TN
I am a 6th year licensed and certified teacher, with a BS in Elementary Education with a fine arts focus, highly qualified in reading, mathematics, writing, and curriculum development. I also am a lic...
5 yrs of exp.
Thompsons Station, TN
I help my 7-year-old brother with his work and I help my 3-year-old brother to learn to read.
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The present invention relates to an apparatus and method for focusing, separating, and detecting gas-phase ions using the principles of quadrupole fields, substantially at or near atmospheric pressure. Ions are entrained in a concentric flow of gas and travel through a high-transmission element into a RF/DC quadrupole, through a second high-transmission element, and then impact on an ion detector, such as a faraday plate; or through an aperture with subsequent identification by a mass spectrometer. Ions with stable trajectories pass through the RF/DC quadrupole while ions with unstable trajectories drift off-axis collide with the rods and are lost. Embodiments of this invention are devices and methods for focusing, separating and detecting gas-phase ions without the need for a vacuum chamber when coupled to atmospheric ionization sources.
1. Apparatus for the focusing and selecting of gas-phase ions and/or particles at or near atmospheric pressure, the apparatus comprising:
a. a dispersive source of ions;
b. a means for providing a concentric flow of gas;
c. a first conductive high-transmission element composed of a surface populated with a plurality of holes and an entrance lens so that said gas and substantially all said ions pass unobstructed through into an multi-element assembly, the said surface and entrance lens being supplied with an attracting electric potential by connection to a high voltage supply, and generating an electrostatic field between said source of ions and top side of said surface;
d. a multi-element assembly for receiving and transmitting gas and focused ions along the z-axis, the said multi-element assembly being supplied with both RF and DC electric potentials by connection to a quadrupole controller so that said multi-element assembly may act as a mass filter for said ions and generating an electrostatic field between backside of said entrance lens and multi-element assembly;
e. a second conductive high-transmission element composed of a second surface populated with a plurality of holes and an exit lens so that substantially all said ions exiting said multi-element assembly pass unobstructed through said second element toward a small cross-sectional area on an ion detector, while said gas passes unobstructed pass ion detector and exits out gas exhaust, the said second surface and exit lens being supplied with an attracting electric potential by connection to a high voltage supply, and generating an electrostatic field between said multi-element assembly and top side of said second surface;
f. an ion detector for detecting substantially all said ions passing through said exit lens, whereby to provide detection of ions separated at or near atmospheric pressure through said mass filter.
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14. Apparatus for the focusing and selecting of an aerosol of gas-phase ions or charged particles at or near atmospheric pressure, the apparatus comprising:
a. a source of ions or charged particles;
b. a concentric flow of gas;
c. a first conductive high-transmission element composed of a surface populated with a plurality of holes and an entrance lens through which gases and substantially all said ions pass unobstructed into an RF/DC quadrupole, the said surface and entrance lens being supplied with an attracting electric potential by connection to a high voltage supply, and generating an electrostatic field between the said source of ions, from atmospheric ion source, and the top side of said surface;
d. a RF/DC quadrupole assembly for receiving and transmitting gas and focused ions along the z-axis, the said quadrupole being supplied with both RF and DC electric potentials by connection to a high voltage supply or quadrupole controller so that said quadrupole assembly may act as a mass filter for said ions and generating an electrostatic field between backside of said entrance lens and said quadrupole assembly and operating at a pressure and voltage as not to form an electrical discharge;
e. a second conductive high-transmission element composed of a second surface populated with a plurality of holes and an exit lens so that substantially all said ions and gas exiting said quadrupole assembly pass unobstructed through said second element toward a small cross-sectional area in an aperture or capillary tube, the said second surface and exit lens being supplied with an attracting electric potential by connection to a high voltage supply, and generating an electrostatic field between the said quadrupole assembly and the top side of said second high transmission surface, while said gas exits through a gas exhaust and aperture;
f. an aperture or capillary tube for receiving substantially all said ions, the said aperture being supplied with an attracting electrostatic potential, and generating an electrostatic field between the backside of said exit lens and said aperture whereby electric field lines are concentrated to a small cross-sectional area on said aperture;
g. an analytical apparatus in communication with the said aperture, wherein said aperture is sandwiched between said exit lens and the analytical apparatus, said cross-sectional area of ions being directed through said aperture into said analytical apparatus, whereby to provide detection of ions separated at or near atmospheric pressure through said quadrupole mass filter.
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21. A method of mass analysis at atmospheric pressure utilizing an ion source region, a focusing region, a RF/DC quadrupole region, and detector region, admitting a concentric flow of gas into said ion source region so that a gas-phase ion and gas may travel through said focusing region, said RF/DC quadrupole region, and into said detector region, and said method comprising:
a. producing ions of a trace substance in said ion source region,
b. directing said gas and ions through a first high transmission element in said focusing region into a RF/DC quadrupole in said RF/DC quadrupole region, first through said focusing region, and then through said RF/DC quadrupole region, and then detecting the ions in said detector region which have passed through said RF/DC quadrupole region, to analyze said substance,
c. placing DC potentials on said first high transmission element so that said first high transmission element acts to guide and focus ions therethrough,
d. placing RF and DC potentials on said RF/DC quadrupole so that said RF/DC quadrupole acts as a mass filter,
e. gas exiting said detector region through gas exhaust,
whereby to provide a means of determining the mass of said ions at atmospheric pressure.
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This application is entitled to the benefit of provisional Patent Application Ser. No. 60/293,648, filed May 26, 2001. In addition this invention uses the high transmission element of our co-pending application, Ser. No. 09/877,167, Filed Jun. 8, 2001.
The invention described herein was made with United States Government support under Grant Number: 1 R43 RR15984-01 from the Department of Health and Human Services. The U.S. Government may have certain rights to this invention.
This invention relates to an atmospheric RF/DC device, specifically to such RF/DC devices which are used for analyzing gas-phase ions at atmospheric pressure.
The analytical utility of a RF/DC (radio frequency/direct current) mass filter or analyzers, such as a quadrupole mass filter, as a device for continuous selection and separation of ions under conventional vacuum conditions is well established. It also has a highly developed theoretical basis (1, 2, 3, 4, 5, 6). The desirable performance attribute of the quadrupole mass filter is the fact that motion in the x, y, and z directions are decoupled, (i e. motion in each direction is independent of motion of the other directions in the Cartesian coordinate system) (7). In general, a time varying potential is applied to opposite sets of parallel rods as illustrated in FIG. 1.
The "hyperbolic" geometry in the x-y plane coupled with the appropriate time-varying applied potential (an RF field) creates a pseudo-potential well that will trap ions within a "stable" mass range along the centerline of the x-y plane (the z-axis), while ejecting ions of "unstable" mass in the x and y directions. In a quadrupole operated a low pressures (under vacuum, <10−3 torr), motion along the z-axis is generally determined by the initial energy of the ions as they enter the quadrupole field, and can be generally considered equivalent to motion in a field free environment. One notable exception to this field-free model would be the effects the fringing fields at the entrance and exit of the quadruple. At the entrance and exit from quadrupoles the x, y and z motions are coupled. This results in the transfer of small amounts of translational energy between the different dimensions. The effects of which can generally be reduced dramatically through electrode design (e.g. the use of RF-only pre- and post-filters).
Ion motion within a quadrupole is well characterized, and is described by the various solutions of the Mathieu equation (8). Simply stated, for a given ion with a particular mass-to-charge ratio (m/z), there exist sets of RF (alternating at the radio frequency) and DC (direct current) voltages, which when applied to a quadrupole yield stable trajectories. These sets of RF and DC voltages can be plotted to represent regions of stability both in the x and y directions (as shown in FIG. 2A). Since motion in the x and y directions are de-coupled, it is convenient to plot both directions in a single plot, focusing on the region(s) where stable trajectories are possible simultaneously in both the x and y directions. This region of stability is designated the "bandpass region".
According to the analytical theory based on the Mathieu equation, any set of voltages which do not lie within one of these regions of stability (in both x and y directions) will result in an unstable trajectory of ions, with exponentially increasing acceleration from the centerline of the quadrupole in the instable direction (x or y). These stability boundaries tend to be very sharp, and can therefore be used to reject certain masses while accepting other masses. Since each mass has a unique set of stable voltages, judicious selection of voltages can allow selection of a narrow bandpass of masses to be transmitted through the quadrupole at the expense of all others as illustrated in FIG. 2B. Quadrupole mass spectrometers are typically scanned through the mass range by increasing both RF and DC voltages while maintaining a constant ratio (see "Scan Line" in FIG. 2B). The slope of the scan line determines the resolution of the mass spectrometer.
There is evidence that these stability boundaries observed with convention quadrupole operation are independent of the operating pressure, and therefore that mass resolution should be possible even for a quadrupoles operated at higher pressures, such as atmospheric pressure. The majority of research with higher pressures has occurred in the pressure range of 1�10−5 to 1�10−1 torr with the three-dimensional quadrupole ion trap (9, 10). It has been clearly observed with three-dimensional quadrupole ion traps that stability boundaries may actually be sharpened at these higher pressures yielding improved resolution. But there are limits with the operating pressures. As the pressure is increased in quadrupole devices the incidence of a gas discharge increases as illustrated in recent studies of ion pipes by Bruce Thomson and coworkers (11).
FIG. 3 illustrates that there are two pressure regimes where time-varying fields can be established at sufficient field strength to affect the radial displacement of unstable ions; the first is at low pressures (<10−2 torr, where existing quadrupole mass analyzers are operated) and the second is at atmospheric pressure (100-760 torr, the present invention). The region marked forbidden at intermediate pressures is limited by gas discharge at the higher voltages (or fields) required for quadrupole mass filtering. In addition, scattering effects from discrete collisions between ions and the surrounding gases deleteriously affect the motion of the ions in the intermediate pressure region as well.
In recent years ion mobility spectrometry (IMS) has become an important analytical tool for measurement of ionized species created in a wide variety of atmospheric pressure ion sources; including, discharge, 63Ni, and photo-ionization. (12, 13) Recently, a number of researchers have also incorporated the LC/MS type sources of electrospray (ES) and atmospheric pressure chemical ionization (APCI) into IMS. (14, 15, 16, 17)
One recent non-conventional implementation of IMS (known as FAIMS, high-field asymmetric waveform ion mobility spectrometry) utilizes an asymmetric waveform to isolate ions between parallel plates or concentric tubes. (18, 19) This technique demonstrates the principal that we propose with the present invention, in that it utilizes a flow of gas along the z-axis coupled with alternating field conditions to create a bandpass spectrometer. Of particular note is the ability to produce field strengths of well over 10,000 volts per cm without discharge occurring. When coupled to ES and mass spectrometry FAIMS has served as an effective means of fractionation of various molecular weight regimes (20).
Nevertheless all the RF/DC mass filters, linear and three-dimensional quadrupoles and FAIMS heretofore known suffer from a number of disadvantages:
(a) Conventional quadrupole mass analyzers require vacuum components; namely, vacuum chambers, high-vacuum electrical feed-throughs, sealed pumpout lines, gauges and others expensive vacuum related devices that can withstand large pressure differences (up to 1000 torr). This requires sufficiently strong materials such as stainless steel, aluminum, or other vacuum compatible materials; chambers with vacuum tight welds; or metal or rubber seals, all with little or no outgassing.
(b) Conventional quadrupole mass analyzers require expensive high vacuum pumps, such as turbomolecular or diffusion pumps; and low vacuum pumps, such mechanical vane pumps; costing many thousands of dollars. The cost of these pumps can makeup approximately 20% of the total cost of an instrument.
(c) Atmospheric interfaces for quadrupole mass analyzers can require multiple stages of rough pumping and expensive high vacuum pumps for operation, resulting in costly and complex interface designs.
(d) Quadrupole mass analyzers weight several hundred pounds and require a substantial amount of electrical power for operation, heating and cooling, etc.; all restricting their portability.
(e) These all add to the manufacturing cost of a quadrupole mass spectrometer thereby resulting in a large percentage (>50%) of the cost of a mass analyzer being due to the cost of the vacuum system components, including the vacuum pumps (both high and low vacuum), chamber, vacuum feed-throughs; atmospheric pressure interfaces; etc.
(f) FAIMS lack the precision and band pass capabilities of quadrupolar designs or other multi-pole designs, by only utilizing 2 parallel plates instead of multiple poles. In essence by utilizing asymmetric RF voltages between parallel plates FAIMS is forming only one-half of the fields seen in quadrupolar designs, therefore stopping short of the precision and band-pass capabilities of quadrupolar devices.
(g) FAIMS's present design suffers from a very inefficient sampling of atmospheric gas-phase ions into the area between the parallel plates.
In accordance with the present invention an atmospheric or near atmospheric RF/DC mass analyzer comprises an atmospheric ion source, an ion-focusing region, an RF/DC quadrupole, an atmospheric gas-phase ion detector, and a source of gas.
Accordingly, besides the objects and advantages of conventional quadrupole mass analyzers described in the previous sections, several objects and advantages of the present invention are:
(a) to provide a RF/DC mass analyzer that can be produced in a variety of materials without requiring the need for materials and/or construction that can withstand large pressure difference and sealing associated with vacuum devices;
(b) to provide a RF/DC mass analyzer which does not require the use of high vacuum pumps;
(c) to provide a RF/DC mass analyzer which does not require high vacuum pumps for atmospheric pressure ion-source interfacing;
(d) to provide a RF/DC mass analyzer which both is lightweight and portable;
(e) to provide a RF/DC mass analyzer whose production allows both for an inexpensive and easily mass produced RF/DC device;
(f) to provide a RF/DC mass analyzer which can provide a precise band-pass capability;
(g) to provide a RF/DC mass analyzer which can efficiently sample gas-phase ions at atmospheric pressure.
Further objects and advantages are to provide an atmospheric RF/DC mass analyzer which can be composed of plastic and other easily molded or composit materials; the rods can be solid, tubes, or make of perforated metal sheets; ion source can be an atmospheric pressure ionization source; such as electrospray, atmospheric pressure chemical ionization, photo-ionization; corona discharge; inductively coupled plasma source, etc.; or ion detector can be an active pixel sensor array. Still further objects and advantages will become apparent for a consideration of the ensuing descriptions and drawings.
The lack of vacuum requirement for the present device will enable the present spectrometer to be fabricated with a wide variety of fabrication alternatives not readily available with vacuum devices, such as micro-machining, micro-lithography for lenses and element, lamination, and molding. The result being a less expensive, smaller, lighter, and more portable detection device.
1 Paul, W., Steinwedel, H., "Mass spectrometer without magnetic field," Z. Naturforsch, 8a, pages 448-450 (1953).
2 Dawson, P. H., "Quadrupole Mass Spectrometry and Its Applications," Elsevier: New York (1976).
3 Miller P. E., Denton, M. B., "The quadrupole mass filter: Basic operating concepts," J. Chem. Ed. 63, pages 617-622 (1986).
4 Steel, C., Henchman, M., "Understanding the quadrupole mass filter through computer simulation," J. Chem. Ed. 75, pages 1049-1054 (1998).
5 Titov, V. V., "Detailed study of the quadrupole mass analyzer operating within the first, second, and third, (intermediate) stability regions. I. Analytical approach," J. Am. Soc. Mass Spectrom 9, pages 50-69 (1998).
6 Gerlich, D., "Inhomogeneous RF fields: A versatile tool for the study of processes with slow ions," IN: State-Selected and State-To-State Ion-Molecule Reaction Dynamics. Part 1. Experiments, Ng, C-Y, Baer, M. (eds.), pages 1-176, John Wiley & Sons: New York (1992).
7 Dawson, P. H., "Chapter 2: Principals of operation," IN: Quadrupole Mass Spectrometry and Its Applications, Dawson, P. H. (ed.), pages 9-64, Elsevier: New York (1976).
8 Dawson. P. H., "Chapter 3: Analytical Theory," IN: Quadrupole Mass Spectrometry and its Applications, Dawson, P. H. (ed.), pages 65-78, Elsevier: New York (1976).
9 Johnson, J. V., Pedder, R. E., Yost, R. A. "The stretched quadrupole ion trap: implications for the Mathieu au and qu parameters and experimental mapping of the stability diagram," Rapid Commun. Mass Spectrom. 6, pages 760-764 (1992).
10 Stafford, G. C., Kelly, P. E., Stephens, D. R., "Method of Mass Analyzing a Sample by Use of a Quadrupole Ion Trap", U.S. Pat. No. 4,540,884 (Sep. 10, 1985).
11 Thomson, B. A., Douglas, D. J., Corr, J. J., Hager, J. W., Jolliffe, C. L., "Improved collisionally activated dissociation efficiency and mass resolution on a triple quadrupole mass spectrometer," J. Am. Soc. Mass Spectrom. 6, pages 1696-1704 (1995).
12 Eiceman, G. A., Karpas, Z., "Ion Mobility Spectrometry," CRC Press: Boca Raton (1994).
13 Hill, H. H., Siems, W. F., St. Louis, R. H., McMinn, D. G. "Ion mobility spectrometry," Anal. Chem. 62, pages 1201A-1209A (1990).
14 Wyttenbach, T., von Helden, G., Bowers, M. T., "Gas-phase conformation of biological molecules: Bradykinin," J. Am. Chem. Soc. 118, pages 8335-8364 (1996).
15 Wittmer, D., Chen. Y. H., Luckenbill, B. K, Hill, H. H., "Electrospray ionization ion mobility spectrometry," Anal. Chem. 66, pages 2348-2355 (1994).
16 Covey, T., Douglas, D. J., "Collision cross sections for protein ions," J. Am. Soc. Mass Spectrom. 4, pages 616-623 (1993)
17 Guevremont, R., Siu, K. W. M., Ding, L., "Ion mobility/TOF mass spectrometric investigation of ions formed by electrospray of proteins," Proceedings of the 45th ASMS Conference on Mass Spectrometry and Allied Topics, page 374, Palm Springs, Calif. Jun. 1-5, 1997.
18 Guevremont, R, Purves, R., Barnett, D., "Method for Separation and Enrichment of Isotopes in gaseous Phase," WO Patent 00/08456 (Feb. 17, 2000). Guevremont, R, Purves, R., "Apparatus and Method for Atmospheric Pressure 3-Dimensional Ion Trapping," WO Patent 00/08457 (Feb. 17, 2000). Purves, R., Guevremont, R, "Electrospray ionization high-field asymmetric waveform ion mobility spectrometry-mass spectrometry," Anal. Chem. 71, pages 2346-2357 (1999).
19 Buryakov, I. A., Krylov, E. V., Nazarov, E. G., Rasulev, U. Kh., "A new method of separation of multi-atomic ions by mobility at atmospheric pressure using a high-frequency amplitude-asymmetric strong electric filed," Int. J. Mass Spectom. Ion Processes. 128, pages 143-148 (1993).
20 Ells, B., Barnett, D. A., Froese, K., Purves, R. W., Hrudey, S., Guevremont, R., "Detection of chlorinated and brominated by products of drinking water disinfection using electrospray ionization-high-field asymmetric waveform ion mobility spectrometrymass spectrometry," R., Anal. Chem. 71, pages 4747-4752 (1999).
In the drawings, closely related figures have the same number but different alphabetic suffixes
FIG. 1 Prior Art. Rod assembly and polarity configuration for a conventional (vacuum) quadrupole. The applied voltages, variable in time t at frequency Ω, showing both the DC component Vdc; and the alternating component Vrf. Vion energy is a fixed DC potential on the rods (commonly referred to as pole bias) that determine the energy of ion in the z-direction.
FIGS. 2A and 2B Prior Art. (2A) x, y-stability regions for a given mass in a quadrupole mass filter, with axis label with rf and dc functions rather than traditional a and q values. The overlap indicates the bandpass region. (2B) The bandpass region of the stability diagram for three masses indicating how they result in mass resolution through rejection of adjacent masses due to instability
FIG. 3 Applied Voltage of the RF (Vrf) (peak-to-peak) versus observed discharge limit as a function of pressure. Both conventional (vacuum) and atmospheric pressure operating regimes are shown.
FIG. 4 is a representation of the essential features of the atmospheric RF/DC device, depicting a quadrupole device. Also shown are the location of the ion source and ion focusing region, with a hemispherical high transmission element for introducing ions into the device, at the entrance of the quadrupole RF/DC filter; the sample and carrier gas inlets; the detector region at the exit of the quadrupole device with a hemispherical high transmission element for collecting and focusing ions into or onto an ion detection apparatus; and gas exhaust.
FIG. 5 is a schematic end view of a quadrupole RF/DC atmospheric filter including the electrically insulating mounting bracket.
FIGS. 6A and 6B are schematic end views of quadrupole RF/DC atmospheric filters with curved surfaces (6A) and rectangular bars (6B), including the electrically insulating mounting brackets.
FIGS. 7A and 7B are schematic end views of hexapole (7A) and octopole (7B) RF/DC atmospheric filter including the electrically insulating mounting brackets.
FIG. 8 is a schematic end view of a monopole RF/DC atmospheric filter.
FIG. 9 is a representation of a RF/DC atmospheric filter, depicting three tandem quadrupole filters.
FIG. 10 is a representation of the atmospheric RF/DC device, the region at the exit of the quadrupole filter is occupied by an atmospheric interface for the introduction of ions into a low pressure mass spectrometer.
10 Ion Source Region
12 gas inlet
14 analyzer housing
20 Focusing Region
22 electrical lead
30 Quadrupole Region
32 electric lead
40 Ion Detector Region
42 electrical lead
44 electrical lead
46 gas-exhaust port
50 conductive electrospray ionization chamber
52 ionization region
54 electrospray needle
56 insulator
60 high transmission element
62 entrance lens
64 insulator
66 aperture
72 atmospheric RF/DC quadrupole filter assembly
74 individual primary electrodes
76 insulator
78 rods
90 Detector Region housing
92 second high transmission element
94 exit lens
96 ion detector
98 ion exit opening
100 rear wall
110 curved shaped surfaces
112 insulator
114 rectangular bar
116 insulator
120 primary electrode
122 primary electrode
124 insulator
130 first filter
132 second filter
134 third filter
170 aperture or capillary tube
180 mass spectrometer region
A preferred embodiment of the atmospheric RF/DC device of the present invention is illustrated in FIG. 4. Basic parts include an Ion Source Region 10, Focusing Region 20, RF/DC Quadrupole Region 30, and Detector Region 40. The Ion Source Region 10 is mounted at one end of the analyzer housing 14 and is symmetrically disposed about the central axis Z. The ion source may comprise, for example, a conductive electrospray ionization chamber 50 comprised of an ionization region 52, an electrospray needle 54, an insulator 56, and a gas inlet 12. A carrier gas is supplied upstream of Ion Source Region 10 through gas inlet 12 from the gas supply source. The gas is generally composed of, but not limited to nitrogen. This device is intended for use in collection and focusing of ions from a wide variety of ion sources at atmospheric or near atmospheric pressure; including, but not limited to electrospray, atmospheric pressure chemical ionization, photo-ionization, electron ionization, laser desorption (including matrix assisted), inductively coupled plasma, and discharge ionization. Both gas-phase ions and charged particles emanating from the Ion Source Region 10 are collected and focused with this device.
A high transmission element 60 is positioned symmetrically about the Z-axis adjacent to the entrance lens 62 and downstream of the Ion Source Region 10, in the Focusing Region 20. The high transmission element (as described in Provisional Patent Application No. 60/210,877, Jun. 9th, 2000) is electrically isolated from the housing 14 and entrance lens 62 by insulators 64. The opening of the entrance lens defines an entrance aperture 66. Electric lead 22 schematically depict the connections required to operate the high transmission element and entrance lens.
Downstream of the Focusing Region 20 is the Quadrupole Region 30 which contains the atmospheric RF/DC quadrupole filter assembly 72. Individual primary electrodes 74 in assembly 72 are held in place and electrically isolated from the cylindrical electrically conductive housing 14 by insulator 76. The primary electrodes 74 are in the form of cylindrical conducting rods or poles extending parallel to one another and disposed symmetrically about the central axis. The X rods lie with their centers in the X-Y plane, and the Y rods lie with their centers on the Y-Z plane Electric lead 32 schematically depict the connections required to operate the quadrupole filter. FIG. 5 illustrates a cross section of the quadrupole. The four rods 78 are held in an equally spaced position and equal radial distance from the centerline by attachment to insulator 76.
A second high transmission element 92 and an exit lens 94 are located downstream of the Quadrupole Region 30, in the Ion Detector Region 40. The Ion Detector Region 40 is enclosed by a housing 90. Electric lead 42 schematically depict the connections required to operate the second high transmission element and exit lens. An ion detector 96, such as a faraday plate or tessalated array detector is symbolically provided with electrical leads 44, and may be conveniently mounted on the exit lens 94. The lens 94 defines an ion exit opening 98 centered on the Z-axis. In addition, a gas-exhaust port 46 is located at the end of the housing 90 downstream of the detector 96.
Additional embodiments are shown in FIGS. 9 and 10.
In FIG. 9 the atmospheric RF/DC filter assembly shows a segmented quadrupole filter in the same manner as FIG. 4, however the filter is composed, in this case, of a primary or first filter 130 and two auxiliary filters, a second filter 132 and a third filter 134 in series.
In FIG. 10 the RF/DC atmospheric focusing device shows an aperture or capillary tube 170 for an atmospheric ionization interface to a mass spectrometer mounted in the Detector Region 40 and is symmetrically disposed about the central axis Z. The rear wall 100 defines an exit aperture 170 centered on the Z axis. Aperture 170 has a diameter appropriate to restrict the flow of gas from the Ion Detector Region 40, at or near atmospheric pressure, to region 180. In the case of a vacuum detection, such as mass spectrometry in region 180, typical aperture diameters are 100 to 500 um.
There are various possibilities with regard to the shape and number of poles of the RF/DC atmospheric filter.
FIG. 6a illustrates a cross section of the Quadrupole Region where the four cylindrically shaped rods (in FIG. 5) are replaced by curved shaped surfaces 110. Insulators 112 serves the dual purpose of supporting the curved surfaces 110 and filling in the space between the edges of the curved surfaces.
FIG. 6b illustrates a cross section of the Quadrupole Region where the four cylindrically shaped rods (in FIG. 5) are replaced with four rectangular bars 114 mounted in insulating materials 116. Insulators 116 serves the dual purpose of supporting the rectangular bars and forming a flush surface where the surface of the bar 114 and the insulator 116 meet.
FIG. 7 illustrates a cross section of the Quadrupole Region where the four cylindrically shaped rods (in FIG. 5) are replaced with either six (a hexapole, FIG. 7a) 78 or eight (an octopole, FIG. 7b) 78 rods.
A monopole filter is illustrated in FIG. 8 and includes primary electrodes 120 and 122. Electrodes 120 and 122 are held by attachment to insulator 124. Electrically the monopole filter is exactly one-fourth of the quadrupole filter. The replacement of three of the rods with a conducting surface in the form of a 90-degree angle plate 122 as shown in FIG. 8 provides the same type of hyperbolic field as that provided in the quadrupole filter illustrated in FIG. 5.
Alternatively, the atmospheric RF/DC filter may be manufactured by using the techniques of microelectronics fabrication: photolithography for creating patterns, etching for removing material, and deposition for coating the surfaces with specific materials.
From the description above, a number of advantages of our atmospheric RF/DC mass filter become evident:
(a) Without the need for a vacuum interface between the ion source and the RF/DC mass filter there is no need for high vacuum pumps, vacuum interlocks and feed-throughs, small apertures for interfacing, all of which are expensive and can complicate the interface design.
(b) Without the need for a vacuum chamber, high vacuum pumps, vacuum feed-throughs, etc., all of which add to the cost of the analyzer, the RF/DC mass analyzer can be mass produced inexpensively.
(c) Being at atmospheric pressure there is no need for vacuum interlocks, thus avoiding the need to vent the system for maintenance or repair.
(d) Not requiring a vacuum chamber and large power requirements of the high vacuum pumps, the mass analyzer can be made of light weight material and not be tethered to one location.
The manner of using the RF/DC atmospheric quadrupole device to collect, focus, and separate ions based on their mass to charge ratio is as follows. Ions supplied or generated in the Ion Source Region 10 from the electrospray source are attracted to the high transmission element 60 by an electrical potential difference between the Ion Source Region 10 and the potential on element 60. The ions will tend to follow the field lines through the Ion Source Region 10 traverse the high transmission element 60 and enter the entrance aperture 66 of the entrance lens 62. Such means are described and illustrated in our U.S. Provisional Filing No. 60/210,877. In addition a sweep gas is also added in Ion Source Region 10. The combination of the potential difference and the flow of the sweep gas cause the ions to be focused at or near a small cross-sectional area at the entrance to the Quadrupole Region 30.
As the ions or charged particles are swept into the Quadrupole Region 30 the RF, or RF and DC potential fields effectively trap the ions in a pseudo-potential well preventing their dispersion in the radial (X-Y) plane. While their movement along the longitudinal z-axis is driven by the gas flow supplied from Ion Source Region 10. RF and DC potentials can be selected to trap specific ions or a range of ions that are stable within the quadrupole assembly 72. At the appropriate RF and DC ratios ions that are not stable will drift off the central axis and eventually collide with rods. The ions that remain in the center are swept out of the quadrupole cylinder exiting out and into the Detector Region 40.
In the operation of this device as an atmospheric inlet to the mass spectrometer (FIG. 10), the detector 96 is replace with an aperture 170 through which focused ions will travel on their path into a vacuum system. Both focusing fields and viscous forces will cause ions in the region of aperture 170 to travel into the vacuum system of the mass spectrometer in region 180. It is intended that this atmospheric RF/DC focusing device be coupled to the vacuum inlet of any conventional mass spectrometer or the atmospheric pressure inlet to any ion mobility spectrometer.
The operation of the present invention will collect and focus ions and charged particles utilizing other configuration of filter assembly 72 (in FIG. 4), such as, single (FIG. 8), or multiple primary electrodes, typically hexapole (FIG. 7a) or octopole (FIG. 7b) filters. These devices operate under the same principles as a quadrupole filter in FIG. 4. Sources of ions are swept through the entrance aperture 66, where RF and DC potentials can be selected to focus and pass ions into the Detector Region. For a monopole the primary electrode 120 is connected to suitable RF and DC potential sources while electrode 122 is connected to ground.
There are also noteworthy alternative operating modes for multipole RF filters in terms of the mass range of ions to be analyzed are different. For example, for a given RF potential, an octopole will transmit ions of wider mass range than a quadrupole. Thus utilizing a quadrupole device for situations where the mass range is narrow, such as for the analysis of gases, i.e, oxygen, carbon dioxide, carbon monoxide, and utilizing an octopole device for application where the mass range is large or unknown, such as for the analysis of proteins.
This invention may also operate in a mode whereby ions are collected and focused with segmented RF/DC filter. This allows different operating values, such as, RF and DC potentials, to be set per filter but increases system complexity and cost. For example, FIG. 9 is a diagram of a RF/DC quadrupole filter with three segmented sections. Ions are swept through the entrance aperture 62 and into the first quadrupole filter 130, where the RF only operation results in virtually all ions and particles being compressed into the center of the quadrupole field. As the focused ions flow into the second quadrupole filter 132, where the RF and DC potentials are selected to act as a low-pass mass filter, larger mass ions and particles are rejected. The remaining ions then enter the last and third quadrupole filter 134, where the RF and DC potentials are selected to pass all the remaining ions, which are then sweep by the carrier gas into the Detector Region 40. In addition, the segmented quadrupole filters can be operated with independent values of frequency and RF and DC potentials, optimizing the transport of ions while eliminating charged particles which may contaminate detectors or clog small apertures. Similar to the continuous RF filter, a segmented RF filter can be used to transport a select range of masses while rejecting ions or charged particles outside this range.
This improved RF and DC atmospheric filter provides the desired focusing and selection of ions at atmospheric or near atmospheric mode of operation by means of an inexpensive and simple structure. The device operates at high efficiency and selectivity as a result of RF and DC excitation and collisional damping compared to that of the prior art systems of focusing and selecting ions and charged particles at atmospheric pressure.
Accordingly, the reader will see that the atmospheric RF/DC mass filter of this invention can be used to separate gas-phase ions from an electrospray ion source based on their mass-to-charge ratio (m/z), can be used as an atmospheric inlet to a mass analyzer; and can be used to pass a wide or a narrow mass range of ions. In addition, segmented quadrupole filters can be operated with independent values of frequency and RF and DC potentials and thus optimizing the passage of ions while eliminating charged particles which may contaminate ion detectors or clog small apertures.
Furthermore, the atmospheric RF/DC filter has the additional advantages in that:
it permits the production of RF/DC filters to be inexpensive;
it provides an atmospheric RF/DC filter which can be made from molded materials;
it provides an atmospheric RF/DC filter which is both lightweight and portable;
it allows access to and maintenance of RF/DC filters to be simple and accomplished without tools;
it allows atmospheric or near-atmospheric ionization sources to be easily interfaced to RF/DC mass filters without the need for complex and costly vacuum system interface; and
it allows for all or nearly all ions formed at atmospheric pressure to be introduced into the RF/DC mass filter.
Although the description above contains many specifications, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of this invention. For example, the RF/DC device can be composed of multiple RF/DC filters in parallel; the rods of the RF/DC device can have other shapes such as, tapered, hourglass, barrel, etc.; the rods can have various cross-sectional shapes, such as circular, oval, hyperbolic, circular trapezoid, etc.; the rods can be composed of solid cylinders, tubes, tubes made of fine mesh, composites, etc.; the ion source region can be composed of other means of atmospheric or near atmospheric ionization, such as photoionization; corona discharge, electron-capture, inductively couple plasma; the ion detector can be have other means of detecting gas-phase ions, such as active pixel sensors, etc.
Thus the scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given.
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