1、Designation: E1510 95 (Reappproved 2013)1Standard Practice forInstalling Fused Silica Open Tubular Capillary Columns inGas Chromatographs1This standard is issued under the fixed designation E1510; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、 of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEWarning statements were editorially corrected in January 2013.1. Scope1.1 This practice covers the
3、installation and maintenance offused silica capillary columns in gas chromatographs that arealready retrofitted for their use. This practice excludes infor-mation on:1.1.1 Injection techniques.1.1.2 Column selection.1.1.3 Data acquisition.1.1.4 System troubleshooting and maintenance.1.2 For addition
4、al information on gas chromatography,please refer to Practice E260. For specific precautions, see7.2.2.2(1), 7.2.2.2(2), 7.2.7, and 7.2.7.2.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 This standard does not purport t
5、o address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For specific safetyinformation, see Section 6, 7.2
6、.2.2(1), 7.2.2.2(2), 7.2.7, and7.2.7.2.22. Referenced Documents2.1 ASTM Standards:3E260 Practice for Packed Column Gas ChromatographyE355 Practice for Gas Chromatography Terms and Relation-ships2.2 CGA Publications:4CGAP-1 Safe Handling of Compressed Gases in ContainersCGA G-5.4 Standard for Hydroge
7、n Piping Systems at Con-sumer LocationsCGA P-9 The Inert Gases: Argon, Nitrogen and HeliumCGA V-7 Standard Method of Determining Cylinder ValveOutlet Connections for Industrial Gas MixturesCGA P-12 Safe Handling of Cryogenic LiquidsHB-3 Handbook of Compressed Gases3. Terminology3.1 Terms and relatio
8、ns are defined in Practice E355.3.2 Nomenclature for open tubular or capillary columnswith a bore of 0.75 mm or less:3.3 porous layer open tubular (PLOT)refers to columnswith particles attached on the inside wall consisting of copo-lymers such as styrene/divinylbenzene, molecular sieves, oradsorbent
9、s such as Al2O2in film thicknesses of 5 to 50 m.3.4 support coated open tubular (SCOT)refers to fineparticles (silica or fine diatomite) coated with liquid stationaryphase, which is then deposited on the inside column wall toimprove stationary phase stability and sample capacity.3.5 wall coated open
10、 tubular (WCOT)refers to columnscoated on the inside wall with a liquid stationary phase in filmthicknesses of 0.1 to 10.0 m. Also referred to as FSOT orfused silica open tubular.4. Summary of Practice4.1 The packed gas chromatography system is described inPractice E260 and is essentially the same a
11、s a capillary gaschromatography system except for modifications to the injectorand detector to accommodate the low flow rates and samplecapacity associated with capillary columns. Refer to the gaschromatography (GC) instrument manual for specific details oninjector or detector pneumatics for capilla
12、ry columns.4.2 Prior to performing a capillary GC analysis, the capil-lary column configuration must be determined. The stationary1This practice is under the jurisdiction of ASTM Committee E13 on MolecularSpectroscopy and Separation Science and is the direct responsibility of Subcom-mittee E13.19 on
13、 Separation Science.Current edition approved Jan. 1, 2013. Published January 2013. Originallyapproved in 1993. Last previous edition approved in 2005 as E1510 95 (2005).DOI: 10.1520/E1510-95R13.2Reprinted by permission of Restek Corp., 110 Benner Circle, Bellefonte, PA16823-8812.3For referenced ASTM
14、 standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.4Available from Compressed Gas Association (CGA), 4221 Walney Rd., 5thFloor, Chan
15、tilly, VA 20151-2923, http:/.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1phase type, stationary phase film thickness, column insidediameter, and column length must be selected. It is beyond thescope of this practice to provide the
16、se details. Consult acolumn or instrument supplier for details on selecting theappropriate capillary column configuration.4.3 Apply caution during handling or installation to avoidscratching or abrading the protective outer coating of thecolumn. Scratches or abrasions cause the fused silica capillar
17、ycolumn to spontaneously break or fail during usage.5. Significance and Use5.1 This practice is intended to be used by all analysts usingfused silica capillary chromatography. It contains the recom-mended steps for installation, preparation, proper installation,and continued column maintenance.6. Ha
18、zards6.1 Gas Handling SafetyThe safe handling of compressedgases and cryogenic liquids for use in chromatography is theresponsibility of every laboratory. The Compressed GasAssociation, a member group of specialty and bulk gassuppliers, publishes the following guidelines to assist thelaboratory chem
19、ist to establish a safe work environment: CGAP-1, CGA G-5.4, CGA P-9, CGA V-7, CGA P-12, and HB-3.7. Installation Procedure for Fused Silica CapillaryColumns7.1 Abrief outline of the steps necessary for installing fusedsilica capillary columns in capillary dedicated gas chromato-graphs is as follows
20、:7.1.1 Cool all heated zones and replace spent oxygen andmoisture scrubbers,7.1.2 Clean or deactivate, or both, injector and detectorsleeves (if necessary),7.1.3 Replace critical injector and detector seals,7.1.4 Replace septum,7.1.5 Set make-up and detector gas flow rates,7.1.6 Carefully inspect th
21、e column for damage or breakage,7.1.7 Cut approximately 10 cm from each end of the columnusing a ceramic scoring wafer or sapphire scribe,7.1.8 Install nut and appropriately sized ferrule on bothcolumn ends,7.1.9 Cut an additional 10 cm from each end of the columnto remove ferrule shards,7.1.10 Moun
22、t the capillary column in the oven using abracket to protect the column from becoming scratched orabraded and to prevent it from touching the oven wall,TABLE 1 Typical Splitter Vent Flow Rates (50 to 1 split ratio)(at optimum linear velocity)Carrier gas0.25-mm ID,cm3/min0.32-mm ID,cm3/min0.53-mm ID,
23、cm3/minheliumhydrogen357080160125250NOTE 1The curves were generated by plotting the height equivalent toa theoretical plate (length of column divided by the total number oftheoretical plates, H.E.T.P.) against the columns average linear velocity.The lowest point on the curve indicates the carrier ga
24、s velocity in whichthe highest column efficiency is reached.NOTE 2Gases information available from Compressed Gas Associa-tion (CGA), 4221 Walney Rd., 5th Floor, Chantilly, VA 20151-2923,http:/.FIG. 1 Van Deemter Profile for Hydrogen, Helium, and NitrogenCarrier GasesCarrier gas: Hydrogen Carrier ga
25、s: HeliumLinear velocity: 40 cm/s Linear velocity: 20 cm/sNOTE 1Fig. 2 shows that the resolution is similar but the analysis timeis reduced by 50 % when comparing hydrogen to helium in an isothermalanalysis using optimum flow velocities.NOTE 2Hydrogen provides similar resolution in one-half the anal
26、ysistime of helium for an isothermal analysis.NOTE 31. Tetrachloro-m- 8. Heptachlor epoxide 15. Endosulfan IIxylene 9. -chlordane 16. DDD2. -BHC 10. Endosulfan I 17. Endrin aldehyde3. -BHC 11. -chlordane 18. Endosulfan sulfate4. -BHC 12. Dieldrin 19. DDT5. -BHC 13. DDE 20. Endrin ketone6. Heptachlor
27、 14. Endrin 21. Methyoxychlor7. AldrinNOTE 430 m, 0.25-mm ID, 0.25 m 5 % diphenyl 95 % dimethylpolysiloxane 0.1-L split injection of chlorinated pesticides.Oven temperature: 210C isothermalInjector and detector temperature: 250C/300CECD sensitivity: 512 1011Split vent: 100 cm3/minFIG. 2 Hydrogen Ver
28、sus Helium (Isothermal Analysis)FIG. 3 Capping Silanol Groups with Dimethyl Dichlorosilane(DMDCS)E1510 95 (Reappproved 2013)127.1.11 Connect the column to the inlet at the appropriatedistance as indicated in the instrument manual,7.1.12 Set the approximate column flow rate by adjustingthe head press
29、ure (see column manufacturers literature),7.1.13 Set split vent, septa purge, and any other applicableinlet gases according to the instrument specifications,7.1.14 Confirm flow by immersing column outlet in a vial ofacetone or methylene chloride,7.1.15 Connect the column to the detector at the appro
30、priatedistance as indicated in the instrument manual,7.1.16 Check for leaks at the inlet or outlet using a thermalconductivity leak detector (do not use soaps or liquid-basedleak detectors),7.1.17 Set injector and detector temperatures and turn ondetector when temperatures have equilibrated (Warning
31、Donot exceed the phases maximum operating temperature),7.1.18 Inject a non-retained substance (usually methane) toset the proper dead time (linear velocity),7.1.19 Check system integrity by making sure dead volumepeak does not tail,7.1.20 Condition the column at the maximum operatingtemperature for
32、2 h (consult column manufacturers literature)to stabilize the baseline,7.1.21 Reinject a non-retained substance (usually methane)to set the proper linear velocity,7.1.22 Run test mixtures to confirm proper installation andcolumn performance, and7.1.23 Calibrate instrument and inject samples.7.2 The
33、following section provides in-depth information oninstrument preparation procedures for installing and operatingfused silica capillary columns in capillary dedicated gaschromatographs:7.2.1 Gas PurificationThe carrier gas must contain lessthan 1 ppm of oxygen, moisture, or any other trace contami-na
34、nts. Otherwise, oxygen and moisture degrade columnperformance, decrease column lifetime, and increase back-ground stationary phase bleed. Contaminants such as tracehydrocarbons cause ghost peaks to appear during temperatureprogramming and degrade the validity of the analytical data.Make-up gas shoul
35、d also be contaminant-free or baselinefluctuations and excessive detector noise may occur. Detectorgases such as hydrogen and compressed air should be free ofwater and hydrocarbon or excessive baseline noise may occur.7.2.1.1 Install purifiers as closely as possible to the GCsbulkhead fitting, rathe
36、r than system-wide. If purifiers areinstalled system-wide, a leaky fitting downstream of thepurifier could allow oxygen and moisture to enter the gasstream and degrade column performance.7.2.1.2 Only highpurity gases should be used for capillarychromatography. All regulators should be equipped with
37、stain-less steel diaphragms. Regulators equipped with rubber orelastomeric diaphragms should not be used because oxygen,moisture, and elastomeric contaminants migrate through thediaphragm and enter the flow.7.2.1.3 Both indicating and non-indicating traps are avail-able from most capillary column su
38、ppliers. Indicating purifiersare recommended since they allow analysts to visually assesswhether the purifier has exceeded its useful life. Also, amoisture trap should be installed prior to the oxygen trap. Ifhydrocarbon contamination is suspected, a hydrocarbon trapshould be installed between the m
39、oisture and oxygen trap.Since most indicating traps are made from glass, care should betaken not to apply lateral torque on the fittings, or they willsnap. To prevent spontaneous breakage of the trap, the lineleading to and from the purifier should be coiled to relievestrain and isolate instrument v
40、ibrations.7.2.2 Carrier Gas SelectionAfast carrier gas that exhibitsa flat van Deemter profile is essential to obtain optimumcapillary column performance. Because capillary columnsaverage 30 m in length (compared to 2 m for packed columns),a carrier gas that minimizes the effect of dead time isimpor
41、tant. In addition, capillary columns are usually headpressure controlled (not flow controlled like most packedcolumns), which cause the carrier gas flow rate to decrease by40 % when the column is programmed from ambient to 300C.Therefore, a carrier gas that retains high efficiency over a widerange o
42、f flow rates is essential towards obtaining good resolu-tion throughout a temperatureprogrammed chromatographicanalysis.7.2.2.1 The optimum average linear gas velocity for hydro-gen (uopt: 40 cm/s) is greater than all the others, and hydrogenexhibits the flattest van Deemter profile. Helium is the n
43、extbest choice (uopt: 20 cm/s). Note that head pressures atNOTE 1Septum bleed can obscure or co-elute with compounds ofinterest, thus decreasing the analytical accuracy.NOTE 21. 2,4,5,6-tetrachloro- 8. Heptachlor 16. p,p-DDDm-xylene (IS) epoxide 17. Endrin aldehyde2. -BHC 9. -chlordane 18. Endosulfa
44、n sul-3. -BHC 10. Endosulfan I fate4. -BHC 11. -chlordane 19. p,p-DDT5. -BHC 12. Dieldrin 20. Endrin ketone6. Heptachlor 13. p,p-DDE 21. Methyoxychlor7. Aldrin 14. Endrin 22. Decachlorobi-15. Endosulfan II phenyl (IS)NOTE 330 m, 0.53-mm ID, 0.50 m 5 % diphenyl 95 % dimethylpolysiloxane 0.1 L direct
45、injection of 50 pg pesticide standard.Oven temperature: 150 to 275C at 4C/min,hold15minInjector temperature: 250C Detector temperature: 300CCarrier gas: HeliumLinear velocity: 40 cm/s (Flow rate: 10 cm3/min)ECD sensitivity: 8 1011AFSFIG. 4 ECD Septum BleedE1510 95 (Reappproved 2013)13optimum flow ra
46、tes are similar for hydrogen and heliumbecause hydrogen has half the viscosity but double the linearvelocity as helium. Because of the low optimum linear velocity(uopt: 10 cm/s) and steep van Deemter profile, nitrogen givesinferior performance with capillary columns and is usually notrecommended.7.2
47、.2.2 Temperature programming usually provides similaranalysis times between hydrogen and helium since the elutionof most compounds strongly depends on the oven temperature.Therefore, the savings in analysis times are not as great aswhen isothermal oven conditions are utilized. In addition,slower car
48、rier gases, such as helium, can improve the separa-tion of very low boiling or early eluting compounds since theyallow more interaction with the stationary phase. Fig. 5illustrates that hydrogen is only slightly faster than heliumwhen both carrier gases are operated under the same tempera-ture to pr
49、ogrammed conditions. Also, note that helium im-proves the resolution of the early eluting compounds (Peaks 1and 2) as compared to hydrogen for a temperature programmedanalysis.(1) WarningExert caution when using hydrogen as acarrier gas. Hydrogen is explosive when concentrations exceed4 % in air and should only be used by individuals who havereceived proper training and understand the potential hazards.Proper safety precautions should be utilized to prevent anexplosion in the oven chambe
