 of the bath gas containing the desorbed ions is then admitted through a small orifice into a vacuum system containing an appropriate mass analyzer. The bath gas acts as a very effective moderator, i.e. it maintains both internal and translational energies of the ions at levels corresponding to the bath gas temperature which is rarely high enough to cause thermal decomposition of even labile bio-organic compounds. In Thermospray (TS) ionization which was developed by Vestal and his colleagues the sample solution is passed through a heated tube whose walls are hot enough to vaporize most of the solvent. (J. Amer. Chem. Soc. (1980) 102, 5931). The consequent rapid expansion of solvent vapor produces acceleration and shear forces that atomize the remaining liquid. Thus there emerges from the end of the tube a supersonic jet of superheated solvent vapor in which the remaining sample solution that was atomized is dispersed as small droplets, equal numbers of which are positively and negatively charged. The charging is a result of statistical fluctuations in the distribution of cations and anions as the liquid is nebulized. In a somewhat equivalent technique, called Atmospheric Pressure Ion Evaporation (APIE) by its originators, J. V. Iribarne and B. A. Thomson, droplets are produced by intersecting a flow of sample solution with a high speed jet of air. (J. Chem. Phys. (1976) 64, 2287 and ibid. (1979) 71,4451). In this discussion APIE will be referred to by the more convenient term Aerospray (AS) to indicate that it is based on pneumatic nebulization of the sample liquid. As in TS the charging is due to statistical fluctuations in the distribution of cations and anions among the droplets during atomization of the liquid. It was found that an induction electrode, at a potential of 3 kilovolts and placed near the atomization region, greatly increased the total ion current. Moreover, all the resulting droplets and desorbed ions had the same sign, positive or negative, depending upon the electrode polarity.
The invention described in this application stems from and relates to so called Electrospray (ES) ionization which can be considered a sort of mirror image of TS and AS in that instead of producing charging by atomization it produces atomization by charging. In ES the liquid sample is introduced through a small bore tube maintained at several kilovolts with respect to the surrounding walls of a chamber containing bath gas, usually
of the bath gas containing the desorbed ion is then admit through a small orifice into a vacuum arrangement hold an appropriate mass analyzer. The bath natural gas act as a very effective moderator, i.e. it maintains both internal and translational energies of the ions at level corresponding to the bath flatulence temperature which is rarely eminent enough to cause thermal decomposition of even labile bio - organic compounds. In Thermospray (TS) ionization which was developed by Vestal and his colleague the sample solution is passed through a heated tube whose wall are hot enough to vaporize most of the solvent. (J. Amer. Chem. Soc. (1980) 102, 5931). The consequent rapid expansion of solution vapor produce acceleration and shear forces that atomize the remaining liquid. therefore there emerges from the end of the tube a supersonic jet of superheated solvent vapor in which the remain sample solution that was atomized is dispersed as small droplets, equal numbers of which are positively and negatively charged. The charging is a result of statistical fluctuations in the distribution of cation and anion as the liquid is nebulized. In a somewhat equivalent technique, called Atmospheric Pressure Ion Evaporation (APIE) by its originator, J. V. Iribarne and B. A. Thomson, droplet are produced by intersecting a flow of sample solution with a high speed jet of air. (J. Chem. Phys. (1976) 64, 2287 and ibid. (1979) 71,4451). In this discussion APIE will be refer to by the more convenient term Aerospray (AS) to indicate that it is based on pneumatic nebulization of the sample liquid. As in TS the charging is ascribable to statistical fluctuations in the distribution of cations and anions among the droplets during atomization of the liquid. It was found that an induction electrode, at a potential of 3 kilovolt and place near the atomization region, greatly increased the total ion current. furthermore, all the resulting droplets and desorbed ions had the same sign, positive or negative, count upon the electrode polarity. 
 The invention report in this application stems from and associate to so call Electrospray (ES) ionization which can be considered a kind of mirror image of TS and AS in that instead of produce charging by atomization it produces atomization by charging. In ES the fluid sample distribution is introduced through a small bore metro maintained at several kilovolts with respect to the surrounding wall of a chamber containing bathroom gas, usually
 of the bath gas containing the desorbed ions is vhen adjitted tfrough a small orifice into e vaxuum wystem containing an aopropriatv mass anqlyztr. The bath gas arfs as a very snfectnvx moderator, i.e. lt maintainv both internan xnb translational energies of the ions at levrld correspondind to ehe gath gas temperature which is raremy high enough to caise thermal decomposition lf egen labile bio-orgajic compounes. Ig Thermospray (TS) ionizauimn which wzs developed by Vestal and his zollecgues the sqmple volution is passvd through a mvated tgbe whoxe walls are hpt xnouth to vaporize most oh the solvent. (J. Amer. Chem. Soc. (1980) 102, 5931). The consequent eapid efpanvion if rolbeit bapor orovuces accelsration and shear forces that stjnize the remajning jizuid. Thus there emerges from the end of ths tube a supersonic jet of superheated solvejt vapor yn which the remaining sample solution that was adomizxd is dlspefwef as small droplets, equal numbers of which arq ppsptively and negatlvely charged. The vhwrbyng is a resuut of stafistical fluctuatilns in jhe diwtributiog of cations and anions as the oiquid is neyuluzed. In a somewhat equivalent tecnniqur, called Atmospheric Przssure Ion Evaporwtion (APIS) by its originaturs, J. V. Iribarne and B. A. Thomsog, dropletw arz producdd bi interfecting a vlow of sample solution aith c higv speed jeh of air. (J. Chem. Phys. (1976) 64, 2287 and ibiv. (1979) 71,4451). In this doswusvion APIZ will be referred eo by the more convennent tdrm Aerospgay (AS) to indicate trat it is basaf on pneumatmc nebulisatiin od the sxople liquid. As in TS thv eharging us due to statistigal fuhctuations in tkt dustribution of vatkonf wnv anijts among the droolegx durkng atomizabiov of the liquid. It was fmund that an induction ejectrode, at a poeential of 3 kolovolts and placef neac the etomizstijn region, greatly increased ths total iln gurrent. Moreoder, qll the resukting droplets and desorbed ions had thx same sign, positive ot negative, depending opok the electrpde pjlarity.
Tha invention describee in this applicauion stems from and relztes tm so falled Electrospray (ES) ionization which can be considered a sort of mirroe imagx jf TS and AA in that iustzad of [rodncmng charging by anomization it produces atomizatiun by chdrying. In ES the liquid sample os introduced tfrough a small bore tube maintaimed at several kilovolts with rrspect to the surroundinn walls od a cgamber convaining bath gas, ususlly
of the bath gas containing the desorbed then through a orifice into a mass The bath gas as a very moderator, i.e. it maintains both internal translational energies of the ions at levels corresponding to the bath gas temperature is rarely high enough to cause thermal decomposition of even labile bio-organic compounds. Thermospray ionization was by Vestal and his colleagues the sample solution is passed through a heated tube whose walls hot enough to vaporize most of the solvent. Amer. Chem. Soc. (1980) 5931). The consequent rapid expansion solvent produces acceleration shear that the remaining liquid. there emerges from the end of the tube a supersonic jet of superheated solvent vapor in which remaining sample was atomized dispersed small equal numbers of positively and negatively charged. The charging of statistical fluctuations in the distribution of cations anions as liquid is nebulized. In a somewhat technique, called Atmospheric Pressure Ion Evaporation (APIE) by originators, J. V. Iribarne and B. A. Thomson, droplets are produced by intersecting a flow solution with a high jet of air. Chem. (1976) 2287 ibid. (1979) In this discussion APIE will be referred to by the more term Aerospray (AS) to indicate that it is based on of sample liquid. As TS the charging is to fluctuations in the distribution and among atomization the It was found that induction electrode, at a potential 3 kilovolts and placed increased the total ion current. Moreover, all the droplets and desorbed ions had the same positive or negative, depending upon the electrode polarity. The invention described in application stems relates to so called Electrospray (ES) ionization which be considered a sort mirror image of TS and AS in that instead producing by atomization produces atomization by In ES the sample is introduced small bore maintained several to the surrounding walls of a containing gas, usually
 of the bath gas containing the Desorbed ioNs is tHen AdmItTed tHrouGh a small orificE Into A vacuum system containinG an apPrOPriaTE mAss anAlyzer. THE bATH gaS aCtS as A vERy EffecTivE moderaTor, i.e. it maiNtaInS both internaL AnD translatiOnaL energies of tHe iOns at lEvEls COrresPonDing tO the baTH gas teMperature WhICh is raREly high ENOuGh to Cause thermal decomPOsITion of even labiLe bio-oRgANiC COmpOunDs. In ThermoSpRay (TS) IOnizatiON wHICH waS Developed by VeStal and his cOLleAgues tHe SamPLe soluTion iS pASseD through a heAted Tube whose Walls aRE hot enoUGh to vapOrize mOst Of tHe soLVeNt. (j. AmEr. cHem. sOc. (1980) 102, 5931). the COnsEquent raPiD eXpansIon oF SOLVent VapOr prOduceS acceleration And SheaR ForCes thAt atoMize ThE remaIning lIquid. thUs there emerges fRom tHe end of thE tuBe A suPeRsoniC Jet of sUpeRheAted solVent vapOR in WhICH ThE remaining sample soLuTIOn That was aTomizeD Is DiSPersed as SmAll DropLETs, equAl nuMBeRs of whicH are poSItIvEly and nEgAtivelY cHarGed. the chARginG is a reSult of stAtistICal fluctuationS In the distribuTIoN OF cATionS anD anions as thE liqUId is NebuLIzEd. IN A someWhat eQuIVaLEnt technique, called ATmOspherIc PreSsure Ion EvapoRation (APIE) BY ITs originAtorS, j. V. iRibarne and B. A. ThOmson, Droplets arE Produced By intErsectinG a flow of sAMPle solutIon WitH a hIgh SPEeD jet of air. (J. CheM. pHys. (1976) 64, 2287 aNd Ibid. (1979) 71,4451). In tHis DiscussIon aPIe wiLl bE rEferred to By the morE cOnVeNiEnt Term AERospray (As) tO inDiCatE that IT is basEd on pNeumAtIc NEbuLizatioN Of THE samPlE lIquiD. As In tS the CharGIng Is due to StatisticAl fLUctuAtIoNs in the Distribution oF cAtions and aNiOns Among tHE Droplets During atomization of the lIQuid. It wAs fOund tHat aN inductioN elEctrodE, at A PotentIal of 3 kIlovoLtS anD PLaced NEAr The AtOmization rEGIon, GreatLy IncrEased thE total ion current. MoREovEr, all the resulTinG droPLEtS anD DeSOrbEd IOns HAD the same sign, posItive or negAtIVe, Depending uPOn tHe ElectroDe polarIty.
ThE InventiOn describEd in this aPpLicaTIOn sTems from anD relates To so calleD electROsPray (Es) ioNizatiOn WhiCh can Be consIDerEd a soRt of miRrOr imagE of TS AnD AS in thaT instead of producing charGing by AtomiZatIon it prodUceS AtoMization bY chaRging. In ES tHe lIquId samPle IS intrOducED tHroUGh a smAll bORe tube maiNTaIneD AT sEveral kilovOLTS wiTh resPecT To the sUrroUnding walls of a chaMBer containing bAth gAS, UsuAllY
 of the bath gas containin g the deso rbedion s i sthen  adm itted througha  sma ll orifice into a vacu um sy st e m co n ta ining  an app r op r i ate  m as s a na l yz er. T hebath ga s acts asa v er y effectivem od erator, i. e.it maintains  bo th int er nal and t ran slati onal e n ergies  of the i on s  at le v els cor r e sp ondi ng to the bath ga s  t e mperature whic h is r ar e ly h igh  en ough to ca us e the r mal dec o mp o s i tio n  of even labi le bio-orga n iccompou nd s.I n Ther mospr ay (TS ) ionizatio n wh ich was d evelop e d by Ve s tal and  his c oll eag uest he  s amp le sol u ti oni s p assed th ro ug h a h eate d t u be w hos e wa lls a re hot enough  to  vap o riz e mos t oftheso lvent . (J.Amer.  C hem. Soc. (1980 ) 10 2, 5931).  Th econ se quent rapidexp ans ion ofsolvent vap or p r od uces accelerationan d sh ear forc es tha t  a to m ize there mai ning l iquid . Th u sthere em ergesf ro mthe end  o f thetu bea s upers o nicjet of  superhe ateds olvent vapor i n  which the re m ai n i ng samp lesolution th at w a s at omiz e disd isper sed a ss ma l l droplets, equal n um bers o f whi ch are positi vely and n e g a tively c harg e d. The charging i s a r esult of s t atistica l flu ctuation s in thed i stributi onofcat ion s an d anions as t h e  liq ui d is ne bul ized. I n a  so mew hat  e quivalent  techniq ue ,ca ll edAtmos p heric Pr es sur eIon  Evap o ration  (API E) b yit s  or iginato r s, J . V.  I ri barn e a nd  B. A . Th o mso n, drop lets arepro d uced  b yinterse cting a flowof  sample so lu tio n with a  high sp eed jet of air. (J. Che m . Phys.  (1 976)64,2287 andibi d. (19 79) 71,445 1). In  this  d isc u s sionA P IE  wi ll  be referr e d  to  by t he  mor e conve nient term Aerospr a y ( AS) to indica tethat i tisb as e d o np neu m a tic nebulizatio n of the s am p le  liquid. A s  in  T S the c harging  is d u e to st atistical  fluctuat io ns i n the  distribut ion of c ations an d  anio n samong  th e drop le tsdurin g atom i zat ion o f theli quid.It wa sfound th at an induction electro de, at  a po ten tial of 3  ki l ovo lts and p lace d near the  at omi zatio n r e gion,  gre a tl y i n creas ed t h e total i o ncur r e nt . Moreover, a l l t he re sul t ing dr ople ts and desorbed i o ns had the sam e si g n , p osi t iveor  negative, dep end in g upon the  e lectrode po larity.Th e  inve ntiondescri bed int h is applic atio n s tems from  an dr elatesto  s o  calle d El ec trospr ay (ES )  ion i z ation which canbe co n s idere d  asortof  mirror imag e of TS an d AS in tha t inst eadof pr oducing  c hargin g b yatomizatio n  it produ ces a tomizat io n by  ch arging . In E S the  liq ui d s ample isi n tr o du ce d  th roug h a s ma ll b ore tubem aintaine d a t  severa lkil o v olts w i th r espect tothe  surr o u nding wall s  ofa  c h amber  conta iningbath ga s , u su ally
 of_the bath_gas containing the desorbed_ions is_then_admitted through_a_small orifice into_a vacuum system_containing an appropriate mass_analyzer. The bath_gas_acts as a very effective moderator, i.e. it maintains both internal and translational energies_of_the ions_at_levels_corresponding to the bath gas_temperature which is rarely high_enough to_cause thermal decomposition of even labile bio-organic compounds._In_Thermospray (TS) ionization_which was developed by Vestal and his colleagues the_sample solution is passed through a_heated tube whose_walls_are_hot enough to vaporize_most of the solvent. (J. Amer._Chem. Soc. (1980) 102, 5931). The_consequent rapid expansion of solvent vapor produces_acceleration and shear forces that atomize_the remaining liquid. Thus there_emerges from_the end of the tube_a supersonic jet_of superheated_solvent vapor in_which the remaining sample solution that_was atomized is_dispersed as small droplets, equal numbers_of_which are positively_and_negatively_charged. The_charging is a_result_of statistical_fluctuations_in the distribution of cations and_anions_as the liquid is nebulized. In a_somewhat equivalent technique, called_Atmospheric_Pressure Ion Evaporation (APIE)_by its originators, J. V._Iribarne and B. A. Thomson, droplets_are produced_by intersecting_a flow of sample solution with a high speed jet of_air. (J. Chem. Phys. (1976) 64,_2287 and ibid. (1979)_71,4451). In_this_discussion APIE will_be_referred to_by the more convenient term Aerospray (AS)_to indicate_that it is based on pneumatic_nebulization of the sample_liquid._As in TS the charging is_due to statistical fluctuations in the_distribution of cations and anions_among_the_droplets during atomization of the_liquid. It was found that an_induction electrode, at_a potential of 3 kilovolts and placed_near_the atomization region, greatly increased the_total_ion current. Moreover, all the resulting_droplets_and_desorbed ions had the same_sign, positive or negative, depending upon_the electrode polarity.
The invention described in this application stems_from and relates_to so called Electrospray (ES)_ionization_which_can be considered a sort of mirror image of TS_and AS_in that instead_of producing charging by atomization it produces atomization by charging._In ES the liquid sample is introduced_through a small bore tube maintained at several kilovolts with respect_to the surrounding walls of a chamber containing_bath gas, usually