Why saying the sample was run on a gas chromatograph is nearly meaningless

Saying the sampling was done on a Gas Chromatograph is like saying that you won a car.  Both description are useful in that they help differentiate.

  • In the case of all vehicles, it is useful to distinguish cars from trucks or motorcycles.
  • Whereas in the case of chemical testing, it is useful to distinguish gas chromatography from enzymatic assay testing or breath testing.

But neither initial descriptions give any idea of specifics.

  • In the case of cars, there are different makes, models  and years.
  • Whereas, in gas chromatography there are many different options.

This is why when you are a citizen among us who has been accused of a DUI and the magic number (i.e., the alleged BAC result) is derived from a purported Gas Chromatography result, you need to find a DUI lawyer who knows a lot about the scientific process and what precisely and in detail the configuration and the method of Gas Chromatography used.  You shouldn’t settle for simply someone who has heard of it, but you deserve someone who is a near expert in Gas Chromatography.  So, ask some questions of your potential DUI lawyer.  See what level of familiarity and detail he/she may have.  If their description amounts to a simple answer like its “a car” in our analogy, then maybe you need to look elsewhere.

I had wrote very generally on Gas Chromatography before and the specific training that I had received through the American Chemical Society and Axiom Labs at:

Gas Chromatography and why is it is so important to Pennsylvania DUI arrests

I had further posted on Crimping a Headspace Vial in Gas Chromatography: How not putting the “lid on the jar” can lead to disaster in a DUI case and A large problem in Gas Chromatography: No uniform standard for GC run position or composition

Now let’s take it to another level and start to look at the variations in configuration to turn the description of “a car” into something much more meaningful.  This post will focus on the various non-programmable hardware-related or configuration-related issues.  The specifics of the configuration.  A future post will focus on the programmable or process/protocol-related issues.

In terms of configuration the variables in modern gas chromatography for ETOH or drugs of abuse determination include:

Carrier gas:  In America typically helium is used as the inert gas used to “push” the analytes through the system; although hydrogen is the second most popular method.  [Blogger’s note:  More will be written on this distinction and specifically on the need for blanks between unknown samples]

Harrisburg DUI Lawyer carrier gas  Harrisburg DUI Lawyer GC with hydrogen generator

(pictured above left:  a Gas Chromatograph with helium tank as the carrier gas; and above right:  a Gas Chromatograph with hydrogen generator-the blue box to the right)

Internal standard:  It is a substance added to achieve an “artificial peak” in chromatography when measuring an unknown and in analytical chemistry, it is a chemical substance that is added in a constant amount to samples, the blank and calibration standards in a chemical analysis. The ratio of the unknown analyte signal to the internal standard signal as a function of the analyte concentration of the standards and hence can achieve a known result.  Generally, in alcohol testing it is n-propanol, but for drugs of abuse in particular other internal standards can be used.  [Blogger’s note:  In the future more will be written on the importance of this distinction and especially in terms of the salting out effect]

Injection type:  Direct injection versus headspace methodology versus autosampler  [Blogger’s note:  In the future more will be written on the importance of this distinction]

Harrisburg DUI Lawyer injector port for GC gas chromatography  Harrisburg DUI Lawyer with headspace autosampler

(pictured above to the left is an injection port where one may do a direct injection; and above right is an headspace autosampler) [to see an autosampler in action please go to: A large problem in Gas Chromatography: No uniform standard for GC run position or composition]

Harrisburg DUI Lawyer manual headspace sampler  Harrisburg DUI Lawyer GC headspace installed

(pictured above left is a manual headspace sampler; and pictured above right is an installed headspace autosampler on a gas chromatograph)

Column:  Not all columns are the same.  There are two basic types:  capillary versus packed.  Generally in modern gas chromatography for ETOH and drug of abuse testing, capillary columns are used.  However, there is no universal column (e.g., Restek BAC 1, Restek BAC 2, Agilent DB-ALC 1, Agilent DB-ALC 2, Rxi™-5ms, DB-5)  What type of capillary column is installed majorly affects specific performance.

Harrisburg DUI Lawyer packed column GC2 Harrisburg DUI Lawyer packed column GC

(pictured above left:  uninstalled packed column; and pictured above right:  installed packed column inside of gas chromatograph)

Harrisburg DUI Lawyer uninstalled capillary column  Harrisburg DUI Lawyer with capillary column

(pictured above left:  uninstalled capillary column; and pictured above right:  installed capillary column inside of gas chromatograph)

Number of columns:  The gas chromatograph can be set up so as to accept a single column or two which is referred to as dual columns.  With dual column configuration duplicate testing is possible.

Harrisburg DUI Lawyer dual column inside

(pictured above:  a dual column configuration)

Detector:  Without a detector, a gas chromatograph is just a screening device as it can only denote separation between analytes of interest and not the quantification of those analytes.  The addition of a detector makes the qualitative measure achieved by the gas chromatograph itself (i.e., the separation characteristic) into a combination of qualitative measurement with the quantitative measurement (as achieved separately by the detector).  In gas chromatography there are so many possible detectors that are used, but primarily for ETOH and drugs of abuse testing of unknowns, flame ionization detectors (usually used in ETOH determinations) and/or mass spectrometry (usually used in drugs of abuse) is used.  With mass spectrometry different detectors are available such as Triple Quadrupole configuration.  [Blogger’s note:  Much more will be written on this later]

Harrisburg DUI Lawyer GC-MS with autosampler  Harrisburg DUI Lawyer GC-MS opened

(pictured above left:  a gas chromatograph with a flame ionization detector using an autosampler; and pictured above right:  on the left an open mass spectrometer and on the right an open gas chromatograph)

Harrisburg DUI Lawyer FID flame ionization detector    Harrisburg DUI lawyer exploded view of flame ionization detector

(pictured above left:  an installed FID or Flame Ionization Detector; pictured above right:  an exploded view of flame ionization detector)

Multiple injectors and multiple detectors: There is no end to the configurations that one can develop.  There are GC-FID, GC-MS-MS.  One can have a GC with multiple injector ports too.

Harrisburg DUI Lawyer 2 FID 2 columns and dual injector ports  Harrisburg DUI Lawyer Dual FIDs

(pictured above left:  2 FIDs 2 columns and dual injector ports; and pictured above right:  close up of dual Flame Ionization Detectors)

Harrisburg DUI Lawyer GC-MS-MS    Harrisburg DUI Lawyer dual injectors

(pictured above left:  a GC-MS-MS; pictured above right:  dual injector ports)

An overall perspective:

Harrisburg DUI Lawyer inside of GC-FID oven (pictured above:  Can your DUI attorney identify the basics?  What do the different color arrows represent? If you are a good defense attorney go ahead and post the answer and get credit)


In order to determine whether or not a test is accurate, precise, traceable, reliable, repeatable, trustworthy and true, we must look at these differences.  In order to determine whether or not your DUI attorney knows what he or she is doing, then they must know all of this at a very minimum.




-Justin J. McShane, Esquire, Pennsylvania DUI Attorney

I am the highest rated DUI Attorney in PA as Rated by Avvo.com

You can follow me on Twitter, Facebook or Linkedin

Harrisburg DUI Lawyer Justin J McShane Esquire earns<br />
criminal law certification throguh NBTA

Board Certified Criminal Trial Advocate
By the National Board of Trial Advocacy
A Pennsylvania Supreme Court Approved Agency

xosotin chelseathông tin chuyển nhượngcâu lạc bộ bóng đá arsenalbóng đá atalantabundesligacầu thủ haalandUEFAevertonxosofutebol ao vivofutemaxmulticanaisonbethttps://bsport.fithttps://onbet88.ooohttps://i9bet.bizhttps://hi88.ooohttps://okvip.athttps://f8bet.athttps://fb88.cashhttps://vn88.cashhttps://shbet.atbóng đá world cupbóng đá inter milantin juventusbenzemala ligaclb leicester cityMUman citymessi lionelsalahnapolineymarpsgronaldoserie atottenhamvalenciaAS ROMALeverkusenac milanmbappenapolinewcastleaston villaliverpoolfa cupreal madridpremier leagueAjaxbao bong da247EPLbarcelonabournemouthaff cupasean footballbên lề sân cỏbáo bóng đá mớibóng đá cúp thế giớitin bóng đá ViệtUEFAbáo bóng đá việt namHuyền thoại bóng đágiải ngoại hạng anhSeagametap chi bong da the gioitin bong da lutrận đấu hôm nayviệt nam bóng đátin nong bong daBóng đá nữthể thao 7m24h bóng đábóng đá hôm naythe thao ngoai hang anhtin nhanh bóng đáphòng thay đồ bóng đábóng đá phủikèo nhà cái onbetbóng đá lu 2thông tin phòng thay đồthe thao vuaapp đánh lô đềdudoanxosoxổ số giải đặc biệthôm nay xổ sốkèo đẹp hôm nayketquaxosokq xskqxsmnsoi cầu ba miềnsoi cau thong kesxkt hôm naythế giới xổ sốxổ số 24hxo.soxoso3mienxo so ba mienxoso dac bietxosodientoanxổ số dự đoánvé số chiều xổxoso ket quaxosokienthietxoso kq hôm nayxoso ktxổ số megaxổ số mới nhất hôm nayxoso truc tiepxoso ViệtSX3MIENxs dự đoánxs mien bac hom nayxs miên namxsmientrungxsmn thu 7con số may mắn hôm nayKQXS 3 miền Bắc Trung Nam Nhanhdự đoán xổ số 3 miềndò vé sốdu doan xo so hom nayket qua xo xoket qua xo so.vntrúng thưởng xo sokq xoso trực tiếpket qua xskqxs 247số miền nams0x0 mienbacxosobamien hôm naysố đẹp hôm naysố đẹp trực tuyếnnuôi số đẹpxo so hom quaxoso ketquaxstruc tiep hom nayxổ số kiến thiết trực tiếpxổ số kq hôm nayso xo kq trực tuyenkết quả xổ số miền bắc trực tiếpxo so miền namxổ số miền nam trực tiếptrực tiếp xổ số hôm nayket wa xsKQ XOSOxoso onlinexo so truc tiep hom nayxsttso mien bac trong ngàyKQXS3Msố so mien bacdu doan xo so onlinedu doan cau loxổ số kenokqxs vnKQXOSOKQXS hôm naytrực tiếp kết quả xổ số ba miềncap lo dep nhat hom naysoi cầu chuẩn hôm nayso ket qua xo soXem kết quả xổ số nhanh nhấtSX3MIENXSMB chủ nhậtKQXSMNkết quả mở giải trực tuyếnGiờ vàng chốt số OnlineĐánh Đề Con Gìdò số miền namdò vé số hôm nayso mo so debach thủ lô đẹp nhất hôm naycầu đề hôm naykết quả xổ số kiến thiết toàn quốccau dep 88xsmb rong bach kimket qua xs 2023dự đoán xổ số hàng ngàyBạch thủ đề miền BắcSoi Cầu MB thần tàisoi cau vip 247soi cầu tốtsoi cầu miễn phísoi cau mb vipxsmb hom nayxs vietlottxsmn hôm naycầu lô đẹpthống kê lô kép xổ số miền Bắcquay thử xsmnxổ số thần tàiQuay thử XSMTxổ số chiều nayxo so mien nam hom nayweb đánh lô đề trực tuyến uy tínKQXS hôm nayxsmb ngày hôm nayXSMT chủ nhậtxổ số Power 6/55KQXS A trúng roycao thủ chốt sốbảng xổ số đặc biệtsoi cầu 247 vipsoi cầu wap 666Soi cầu miễn phí 888 VIPSoi Cau Chuan MBđộc thủ desố miền bắcthần tài cho sốKết quả xổ số thần tàiXem trực tiếp xổ sốXIN SỐ THẦN TÀI THỔ ĐỊACầu lô số đẹplô đẹp vip 24hsoi cầu miễn phí 888xổ số kiến thiết chiều nayXSMN thứ 7 hàng tuầnKết quả Xổ số Hồ Chí Minhnhà cái xổ số Việt NamXổ Số Đại PhátXổ số mới nhất Hôm Nayso xo mb hom nayxxmb88quay thu mbXo so Minh ChinhXS Minh Ngọc trực tiếp hôm nayXSMN 88XSTDxs than taixổ số UY TIN NHẤTxs vietlott 88SOI CẦU SIÊU CHUẨNSoiCauVietlô đẹp hôm nay vipket qua so xo hom naykqxsmb 30 ngàydự đoán xổ số 3 miềnSoi cầu 3 càng chuẩn xácbạch thủ lônuoi lo chuanbắt lô chuẩn theo ngàykq xo-solô 3 càngnuôi lô đề siêu vipcầu Lô Xiên XSMBđề về bao nhiêuSoi cầu x3xổ số kiến thiết ngày hôm nayquay thử xsmttruc tiep kết quả sxmntrực tiếp miền bắckết quả xổ số chấm vnbảng xs đặc biệt năm 2023soi cau xsmbxổ số hà nội hôm naysxmtxsmt hôm nayxs truc tiep mbketqua xo so onlinekqxs onlinexo số hôm nayXS3MTin xs hôm nayxsmn thu2XSMN hom nayxổ số miền bắc trực tiếp hôm naySO XOxsmbsxmn hôm nay188betlink188 xo sosoi cầu vip 88lô tô việtsoi lô việtXS247xs ba miềnchốt lô đẹp nhất hôm naychốt số xsmbCHƠI LÔ TÔsoi cau mn hom naychốt lô chuẩndu doan sxmtdự đoán xổ số onlinerồng bạch kim chốt 3 càng miễn phí hôm naythống kê lô gan miền bắcdàn đề lôCầu Kèo Đặc Biệtchốt cầu may mắnkết quả xổ số miền bắc hômSoi cầu vàng 777thẻ bài onlinedu doan mn 888soi cầu miền nam vipsoi cầu mt vipdàn de hôm nay7 cao thủ chốt sốsoi cau mien phi 7777 cao thủ chốt số nức tiếng3 càng miền bắcrồng bạch kim 777dàn de bất bạion newsddxsmn188betw88w88789bettf88sin88suvipsunwintf88five8812betsv88vn88Top 10 nhà cái uy tínsky88iwinlucky88nhacaisin88oxbetm88vn88w88789betiwinf8betrio66rio66lucky88oxbetvn88188bet789betMay-88five88one88sin88bk88xbetoxbetMU88188BETSV88RIO66ONBET88188betM88M88SV88Jun-68Jun-88one88iwinv9betw388OXBETw388w388onbetonbetonbetonbet88onbet88onbet88onbet88onbetonbetonbetonbetqh88mu88Nhà cái uy tínpog79vp777vp777vipbetvipbetuk88uk88typhu88typhu88tk88tk88sm66sm66me88me888live8live8livesm66me88win798livesm66me88win79pog79pog79vp777vp777uk88uk88tk88tk88luck8luck8kingbet86kingbet86k188k188hr99hr99123b8xbetvnvipbetsv66zbettaisunwin-vntyphu88vn138vwinvwinvi68ee881xbetrio66zbetvn138i9betvipfi88clubcf68onbet88ee88typhu88onbetonbetkhuyenmai12bet-moblie12betmoblietaimienphi247vi68clupcf68clupvipbeti9betqh88onb123onbefsoi cầunổ hũbắn cáđá gàđá gàgame bàicasinosoi cầuxóc đĩagame bàigiải mã giấc mơbầu cuaslot gamecasinonổ hủdàn đềBắn cácasinodàn đềnổ hũtài xỉuslot gamecasinobắn cáđá gàgame bàithể thaogame bàisoi cầukqsssoi cầucờ tướngbắn cágame bàixóc đĩaAG百家乐AG百家乐AG真人AG真人爱游戏华体会华体会im体育kok体育开云体育开云体育开云体育乐鱼体育乐鱼体育欧宝体育ob体育亚博体育亚博体育亚博体育亚博体育亚博体育亚博体育开云体育开云体育棋牌棋牌沙巴体育买球平台新葡京娱乐开云体育mu88qh88
Justin McShane

PA DUI attorney Justin J. McShane is the President/CEO of The McShane Firm, LLC - Pennsylvania's top criminal law and DUI law firm. He is the highest rated DUI attorney in PA as rated by Avvo.com. Justin McShane is a double Board certified attorney. He is the first and so far the only Pennsylvania attorney to achieve American Bar Association recognized board certification in DUI defense from the National College for DUI Defense, Inc. He is also a Board Certified Criminal Trial Advocate by the National Board of Trial Advocacy, a Pennsylvania Supreme Court Approved Agency.

3 responses to “Why saying the sample was run on a gas chromatograph is nearly meaningless”

Leave a Reply

Your email address will not be published. Required fields are marked *