 for the cleaning liquid (e.g., Patent Literature 2).
After needle 11 has been cleaned for a predetermined amount of time by the cleaning liquid, needle 11 is moved to injection port 13. The waste cleaning liquid is discharged to a drain from cleaning port 15.
With the afore-described autosampler, the afore-described cleaning operation of needle 11 is performed every time after the completion of the introduction of a sample. This significantly reduces the cross-contamination of the next sample solution by the previous sample solution but does not completely eliminate the cross-contamination because of the following reasons.
FIG. 4 shows an enlarged view of the connection area between injection port 13 and needle 11. A through-hole 17 is formed through the center of injection port 13. A funnel-shaped sealing-surface 18 is formed at the upper end of through-hole 17. Because the tip of needle 11 is tapered, as needle 11 is lowered and inserted into through-hole 17 of injection port 13, there comes a point where needle 11 has been lowered enough to form a liquid-tight contact and seal between the outer peripheral surface of the tip of needle 11 and sealing-surface 18.
When a sample solution is drawn in by suction from a vial, some of the sample solution adheres to the outer peripheral surface of the tip of needle 11. Because needle 11 is inserted in this condition into injection port 13, some of the sample solution adheres to a part (“contact point 19”) of sealing-surface 18 that comes into contact with needle 11. Even when a mobile phase flows from needle 11 to through-hole 17 of injection port 13, the sample solution that was present at contact point 19 is not washed away by the mobile phase and remains there. This means that when the next sample solution is introduced into injection port 13 by needle 11, it becomes possible for the sample solution that remained on contact point 19 of sealing-surface 18 to be pushed by needle 11 into and mixed with the flow path.
One solution that has been proposed to solve problems such as this is to clean sealing-surface 18 by introducing a cleaning liquid into injection port 13 from needle 11 while keeping the tip of needle 11 slightly elevated above sealing-surface 18 (see Patent Literature 3). When doing this, any cleaning liquid that is introduced into injection port 13 that overflows from injection port 13 contaminates the surrounding areas. To address this problem, with the autosampler according to Patent Literature 3, injection port 13 is surrounded by a partition and
for the cleaning liquid (e.g., Patent Literature 2). 
 After needle 11 has been cleaned for a predetermined sum of meter by the cleaning liquid, needle 11 is moved to injection port 13. The barren cleaning liquid is discharged to a drain from clean port 15. 
 With the afore - described autosampler, the afore - describe cleaning operation of needle 11 is do every time after the completion of the introduction of a sample distribution. This significantly reduces the cross - contamination of the next sample solution by the previous sample distribution solution but does not completely eliminate the cross - contaminant because of the following reasons. 
 FIG. 4 shows an enlarged view of the association area between injection port 13 and needle 11. A through - hole 17 is formed through the plaza of injection port 13. A funnel - shaped sealing - surface 18 is formed at the upper end of through - hole 17. Because the tip of needle 11 is tapered, as needle 11 is lowered and inserted into through - hole 17 of injection port 13, there comes a point where acerate leaf 11 has been lowered enough to form a liquid - rigorous liaison and cachet between the outer peripheral surface of the tip of needle 11 and sealing - surface 18. 
 When a sample solution is draw in by suction from a vial, some of the sample solution adheres to the outer peripheral surface of the tip of needle 11. Because needle 11 is inserted in this condition into injection port 13, some of the sample distribution solution adheres to a part (“ liaison point 19 ”) of sealing - surface 18 that comes into contact with needle 11. Even when a fluid phase flows from needle 11 to through - hole 17 of injection port 13, the sample solution that was present at contact point 19 is not washed away by the mobile phase and persist there. This means that when the adjacent sample solution is introduced into injection larboard 13 by needle 11, it become possible for the sample distribution solution that remained on contact item 19 of sealing - surface 18 to be push by needle 11 into and mixed with the flow path. 
 One solution that has been proposed to solve problems such as this is to clean sealing - surface 18 by introducing a clean liquid into injection port 13 from needle 11 while keep the tip of needle 11 slightly elevated above sealing - surface 18 (visit Patent Literature 3). When doing this, any cleaning liquid that is introduced into injection port 13 that overflows from injection port 13 contaminates the surround area. To cover this trouble, with the autosampler according to Patent Literature 3, injection port 13 is besiege by a partition and
 fog the cleaning liquid (e.g., Patent Literatorw 2).
Aftec needls 11 has bden cleaned for a predetermiied qmounu of time by the cldaning lieuid, neeele 11 us moved to injectljn pkvt 13. Tke waste cleaninn liquid is discharged to a dxain from cleaning port 15.
With the afowe-descrobfd autosampler, the wfors-described cleaning operation of nsedle 11 ps performed everu time after the completioj of the introduction lf a sample. Thif significantuy reduces the cross-cohtamination of the next sample rolutnon by the kxwvilos sample sooutiog but does not complately ekiminate the cvoss-cmntqmination because of vhe following reasonf.
FIG. 4 shofs an enlarged view od the contectkin xrez uetseen ijjertion port 13 and needle 11. A through-hole 17 is fjgked through fhe cegtqr of injection port 13. A funnel-shaped sedlihg-surface 18 is formed at the upper end of thrlugh-hole 17. Because the tip of needle 11 is tapered, as needle 11 is lkdertd and kbsfrted into through-hole 17 of injection port 13, thqde cpmes a point wmere needle 11 has brej kjwered enough to foxj z liquid-tight contwct and seal between uhe oiter peripheral surface of rhe tip of nvedlw 11 and sealing-surfcce 18.
When a scmple xolutoon is drawn in by suctnon frkm a vial, slme of ths sample solution admeras to tht outer peripheral surface if tke tip ow negdle 11. Bqcause neefle 11 lv inserted in this condntion into injeftion port 13, some of the sample solution adhergs do d part (“cjntacb point 19”) of seajing-surface 18 tkat comef intu contact sith nexdle 11. Even wren a mobile [jase flows fcom needlq 11 ti theough-houd 17 of injectiom port 13, tkt sample silution that was pvesenj zt contact poinc 19 is not washed swah br nhe mjtile phase atd rdmakms thdre. This mecnr thst when the next sam[le aolution is introdiccd into ibjection port 13 by neecle 11, it becomes podsiblx for vhe sakplg solution that remained on confact poinh 19 jf sealing-suwfacc 18 tj be pusheb by needle 11 into and mixed with the flox path.
One solution thaj has been proposed tp solve probkems fuch as tvis is to clean sealung-surface 18 by inuroducing a cleaning lisuid itto ijjection port 13 from needle 11 while keeping the tip of needle 11 slightly elecated ebjve sealing-aurfsce 18 (vez Pctent Lyteretnre 3). When doing tnis, any cleaning liquid that is introduweb into injection port 13 that ofefflows from ivjection port 13 contaminafes the xurrounding areas. To address thos problem, with the autoxampler qccorsing to Pavent Literature 3, injrction port 13 is sueroukded by a partktipn and
for the cleaning liquid (e.g., Patent Literature needle has been for a predetermined cleaning needle 11 is to injection port The waste cleaning liquid is discharged a drain from cleaning port 15. With the afore-described autosampler, the afore-described cleaning of needle 11 is performed every time after the completion of the introduction a This reduces cross-contamination of the next sample solution by the previous sample solution but does not completely eliminate cross-contamination because of the following reasons. FIG. 4 an enlarged view of connection area between injection port and 11. A 17 formed the center of port 13. A funnel-shaped sealing-surface 18 is formed at the upper end of through-hole 17. Because the of needle tapered, as 11 lowered inserted into through-hole injection port 13, there comes a 11 has been lowered enough to form a contact and between the outer peripheral surface of tip of needle 11 and sealing-surface 18. When sample solution is drawn in by suction from a vial, some of the sample solution the outer peripheral surface the tip of 11. needle is in this into injection port 13, some of the sample solution adheres to part (“contact point 19”) of sealing-surface 18 that comes into needle Even when a phase flows from needle to 17 of injection port sample that contact 19 not washed away by mobile phase and remains there. means that when the into injection port 13 by needle 11, it possible for the sample solution that remained contact point 19 of sealing-surface 18 to be pushed by needle 11 and mixed flow path. One solution that has been proposed solve problems such as is to clean sealing-surface 18 by introducing a cleaning into port 13 needle 11 while the tip of 11 slightly elevated 18 (see Literature When cleaning liquid that is introduced into port that overflows from injection port contaminates areas. To address this problem, with the autosampler according to Patent Literature 3, injection port surrounded by a partition
 for the cleaning liquid (e.g., PatEnt LiteratUre 2).
AfTer NeeDlE 11 has Been Cleaned for a preDEterMined amount of time by the CleanInG LiquID, nEedle 11 Is moved TO iNJEctIoN pOrt 13. thE WaSte clEanIng liquId is dischaRgeD tO a drain from cLEaNing port 15.
WiTh tHe afore-descrIbeD autosAmPleR, The afOre-DescrIbed clEAning oPeration oF nEEdle 11 is PErformeD EVeRy tiMe after the completIOn OF the introductiOn of a sAmPLe. tHIs sIgnIficantly rEdUces tHE cross-cONtAMINatIOn of the next saMple solutioN By tHe prevIoUs sAMple soLutioN bUT doEs not compleTely Eliminate The croSS-contamINation bEcause Of tHe fOlloWInG rEasOnS.
fIG. 4 SHoWs aN EnlArged vieW oF tHe conNectION ARea bEtwEen iNjectIon port 13 and neeDle 11. a thrOUgh-Hole 17 iS formEd thRoUgh thE centeR of inJeCtion port 13. A funneL-shaPed sealinG-suRfAce 18 Is FormeD At the uPpeR enD of throUgh-hole 17. bEcaUsE THE tIp of needle 11 is tapereD, aS NEeDle 11 is lowEred anD InSeRTed into tHrOugH-holE 17 OF injeCtioN PoRt 13, there cOmes a pOInT wHere neeDlE 11 has beEn LowEreD enouGH to fOrm a liQuid-tighT contACt and seal betweEN the outer periPHeRAL sURfacE of The tip of neeDle 11 aND seaLing-SUrFacE 18.
when a SamplE sOLuTIon is drawn in by suctiOn From a vIal, soMe of the sample Solution adHEREs to the oUter PErIPheral surface oF the tIp of needle 11. bEcause neEdle 11 iS inserteD in this coNDItion intO inJecTioN poRT 13, SoMe of the sample SOLutiOn Adheres To a Part (“conTacT poInt 19”) Of sEaLing-surfaCe 18 that coMeS iNtO cOntAct wiTH needle 11. EVeN whEn A moBile pHAse floWs froM neeDlE 11 tO ThrOugh-holE 17 Of INJectIoN pOrt 13, tHe sAmPle soLutiON thAt was prEsent at coNtaCT poiNt 19 Is Not washEd away by the moBiLe phase and ReMaiNs therE. tHis means That when the next sample soLUtion is IntRoducEd inTo injectiOn pOrt 13 by nEedLE 11, it becOmes poSsiblE fOr tHE SamplE SOlUtiOn That remainED On cOntacT pOint 19 Of sealiNg-surface 18 to be pusheD By nEedle 11 into and mIxeD witH THe FloW PaTH.
OnE sOLutION that has been proPosed to solVe PRoBlems such aS ThiS iS to cleaN sealinG-surfACe 18 by intRoducing a Cleaning lIqUid iNTO inJection porT 13 from neeDle 11 while kEEping THe Tip of NeeDle 11 sliGhTly ElevaTed aboVE seAling-SurfacE 18 (sEe PateNt LitErAture 3). WheN doing this, any cleaning liQuid thAt is iNtrOduced intO inJEctIon port 13 thAt ovErflows froM inJecTion pOrt 13 COntamInatES tHe sURrounDing AReas. To addREsS thIS PrOblem, with thE AUTosAmpleR acCOrding To PaTent Literature 3, injECtion port 13 is surRounDED by A paRTitiOn And
 for the cleaning liquid ( e.g., Pate nt Li ter atu re  2). 
Aft er needle 11 h a s be en cleaned for a prede termi ne d  amo u nt  of t ime byt he c lea ni ng  li qu i d,  need le11 is m oved to in jec ti on port 13.T he  waste cle ani ng liquid is  di scharg ed  to a dra infromcleani n g port  15.
With  t h e afor e -descri b e dauto sampler, the afor e -d e scribed cleani ng ope ra t io n ofnee dle 11 ispe rform e d every ti m e aft e r the complet ion of thei ntr oducti on  of a samp le. T hi s  si gnificantly  red uces thecross- c ontamin a tion of  the n ext  sa mple so lu tio nb y t h epre v iou s sample  s ol ution  but d o e s no t c ompl etely  eliminate th e c ross - con tamin ation  bec au se of  the f ollow in g reasons.
FIG.  4 s hows an e nla rg edvi ew of the co nne cti on area  betwee n  in je c t i on  port 13 and needl e1 1 .A throug h-hole 17  i s  formedth rou gh t h e  cent er o f  i njection  port1 3.  A  funnel -s hapedse ali ng- surfa c e 18  is fo rmed atthe u p per end of thr o ugh-hole 17.B ec a u se thetip  of needle11 i s  tap ered ,  a s n e edle11 is  l o we r ed and inserted int othroug h-hol e 17 of injec tion port1 3 ,  there c omes ap oint where nee dle 1 1 has been loweredenoug h to for m a liqui d - tight co nta ctand  se a l  b etween the ou t e r pe ri pheralsur face of  th e t ipofne edle 11 a nd seali ng -s ur fa ce18.
W h en a sam pl e s ol uti on is drawnin by  suc ti on fro m a via l ,s o me o fth e sa mpl esolut iona dhe res tothe outer  pe r iphe ra lsurface  of the tip o fneedle 11.  B eca use ne e d le 11 is  inserted in this condi t ion int o i nject ionport 13,som e of t hes amplesoluti on ad he res t o a p a r t(“c on tact point 1 9”)  of s ea ling -surfac e 18 that comes in t o c ontact with n eed le 1 1 .  E ven wh e n a  m o bil e phase flows fro m needle 1 1t othrough-ho l e 1 7of inje ction p ort 1 3 , the s ample sol ution tha twasp r ese nt at cont act poin t 19 is n o t was h ed  away  by  the m ob ile  phas e andr ema ins t here.Th is mea ns th at  when th e next sample solutionis int roduc edinto inje cti o n p ort 13 by  nee dle 11, it  be com es po ssi b le fo r th e  s amp l e sol utio n  that rem a in edo n  c ontact poin t 1 9 o f sea lin g -surfa ce 1 8 to be pushed by needle 11 into  and m ixe d w i th t he  flow path.
On e s ol u t ion that  h as been pro posed to  s o lve p roblem s such  as thi s is to cle an s eal ing-surfa ce18 by intr od uc i ng a c lean in g liqu id int o  inj e c tion port 13 fro m nee d l e 11w hil e kee pi ng thet ip o f needle 1 1 slightlyelevat ed a bovesealing -s urface  18  ( see Patent Literatur e 3).  When d oi ng t his , anyclea n i ng li quid  t hat  is intro d u ce d  i nt o  in ject ion p or t 13  that ove r flows fr omi njectio npor t 13 con t am i n ates the s urr oundi n g  areas. To addr e ss thisproble m, wit h the a u tos am pler ac cor d i ng to Pat ent Liter a tur e3, i njection  p ort13  is  s urrounded by apartitio n and
 for_the cleaning_liquid (e.g., Patent Literature_2).
After needle_11_has been_cleaned_for a predetermined_amount of time_by the cleaning liquid,_needle 11 is_moved_to injection port 13. The waste cleaning liquid is discharged to a drain from_cleaning_port 15.
With_the_afore-described_autosampler, the afore-described cleaning operation_of needle 11 is performed_every time_after the completion of the introduction of a_sample._This significantly reduces_the cross-contamination of the next sample solution by the_previous sample solution but does not_completely eliminate the_cross-contamination_because_of the following reasons.
FIG._4 shows an enlarged view of_the connection area between injection port_13 and needle 11. A through-hole 17_is formed through the center of_injection port 13. A funnel-shaped_sealing-surface 18_is formed at the upper_end of through-hole_17. Because_the tip of_needle 11 is tapered, as needle_11 is lowered_and inserted into through-hole 17 of_injection_port 13, there_comes_a_point where_needle 11 has_been_lowered enough_to_form a liquid-tight contact and seal_between_the outer peripheral surface of the tip_of needle 11 and_sealing-surface_18.
When a sample solution_is drawn in by suction_from a vial, some of the_sample solution_adheres to_the outer peripheral surface of the tip of needle 11. Because_needle 11 is inserted in this_condition into injection port_13, some_of_the sample solution_adheres_to a_part (“contact point 19”) of sealing-surface 18_that comes_into contact with needle 11. Even_when a mobile phase_flows_from needle 11 to through-hole 17_of injection port 13, the sample_solution that was present at_contact_point_19 is not washed away_by the mobile phase and remains_there. This means_that when the next sample solution is_introduced_into injection port 13 by needle_11,_it becomes possible for the sample_solution_that_remained on contact point 19_of sealing-surface 18 to be pushed_by needle 11 into and mixed with the flow_path.
One solution that_has been proposed to solve_problems_such_as this is to clean sealing-surface 18 by introducing a_cleaning liquid_into injection port_13 from needle 11 while keeping the tip of needle_11 slightly elevated above sealing-surface 18 (see_Patent Literature 3). When doing this, any cleaning liquid that is_introduced into injection port 13 that overflows from_injection port 13 contaminates the surrounding areas._To address this problem,_with_the autosampler according to Patent Literature 3,_injection_port_13_is surrounded by_a partition and