1、Designation: E 1510 95 (Reappproved 2005)Standard Practice forInstalling Fused Silica Open Tubular Capillary Columns inGas Chromatographs1This standard is issued under the fixed designation E 1510; the number immediately following the designation indicates the year oforiginal adoption or, in the cas
2、e of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the installation and maintenance offused silica capillary columns in
3、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 additional information on gas chromatography,please refer to Practice E 2
4、60. For specific precautions, seeNotes 1-4.1.3 This standard does not purport to 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 regulato
5、ry limitations prior to use. For specific safetyinformation see Section 6 and Notes 2-4.22. Referenced Documents2.1 ASTM Standards:3E 260 Practice for Packed Column Gas ChromatographyE 355 Practice for Gas Chromatography Terms and Rela-tionships2.2 CGA Publications:4CGA P-1 Safe Handling of Compress
6、ed Gases in Contain-ersCGA G-5.4 Standard for Hydrogen 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 o
7、f Compressed Gases3. Terminology3.1 Terms and relations are defined in Practice E 355.3.2 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 copoly-mers such as
8、 styrene/divinylbenzene, molecular sieves, oradsorbents 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 ph
9、ase stability and sample capacity.3.5 wall coated open tubular (WCOT)refers to columnscoated on the inside wall with a liquid stationary phase in film1This practice is under the jurisdiction of ASTM Committee E13 on MolecularSpectroscopy and Chromatography and is the direct responsibility of Subcomm
10、itteeE13.19 on Chromatography.Current edition approved Feb. 1, 2005. Published March 2005. Originallyapproved in 1993. Last previous edition approved in 2000 as E 1510 95(2000).2Reprinted by permission of Restek Corp., 110 Benner Circle, Bellefonte, PA16823-8812.3For referenced ASTM standards, visit
11、 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), 1725 Jefferson DavisHwy., Suite 1004, Arlington,
12、 VA 22202-4102.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,cm3/minheliumhydrogen357080160125250NOTE 1The curves were generated by plotting the height equivalentto a theoretical plate (length of co
13、lumn 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 gas velocity in whichthe highest column efficiency is reached.FIG. 1 Van Deemter Profile for Hydrogen, Helium, and NitrogenCarrier Gases41C
14、opyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.thicknesses 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 E 260 and is esse
15、ntially the same as 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 pneu
16、matics for capillary columns.4.2 Prior to performing a capillary GC analysis, the capil-lary column configuration must be determined. The stationaryphase type, stationary phase film thickness, column insidediameter, and column length must be selected. It is beyond thescope of this practice to provid
17、e these 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 cap
18、illarycolumn 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.
19、6. Hazards6.1 Gas Handling SafetyThe safe handling of compressedgases and cryogenic liquids for use in chromatography is theresponsibility of every laboratory. The Compressed Gas Asso-ciation, a member group of specialty and bulk gas suppliers,publishes the following guidelines to assist the laborat
20、orychemist to establish a safe work environment: CGA P-1, CGAG-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
21、follows:7.1.1 Cool all heated zones and replace spent oxygen andmoisture scrubbers,Carrier gas: Hydrogen Carrier gas: 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
22、an isothermalanalysis using optimum flow velocities.NOTE 2Hydrogen provides similar resolution in one-half the analysistime of helium for an isothermal analysis.NOTE 31. Tetrachloro-m- 8. Heptachlor epoxide 15. Endosulfan IIxylene 9. g-chlordane 16. DDD2. a-BHC 10. Endosulfan I 17. Endrin aldehyde3.
23、 b-BHC 11. a-chlordane 18. Endosulfan sulfate4. g-BHC 12. Dieldrin 19. DDT5. d-BHC 13. DDE 20. Endrin ketone6. Heptachlor 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
24、isothermalInjector and detector temperature: 250C/300CECD sensitivity: 512 3 1011Split vent: 100 cm3/minFIG. 2 Hydrogen Versus Helium (Isothermal Analysis)FIG. 3 Capping Silanol Groups with Dimethyl Dichlorosilane(DMDCS)NOTE 1Septum bleed can obscure or co-elute with compounds ofinterest, thus decre
25、asing the analytical accuracy.NOTE 21. 2,4,5,6-tetrachloro- 8. Heptachlor 16. p,p-DDDm-xylene (IS) epoxide 17. Endrin aldehyde2. a-BHC 9. g-chlordane 18. Endosulfan sul-3. b-BHC 10. Endosulfan I fate4. g-BHC 11. a-chlordane 19. p,p-DDT5. d-BHC 12. Dieldrin 20. Endrin ketone6. Heptachlor 13. p,p-DDE
26、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 injection of 50 pg pesticide standard.Oven temperature: 150 to 275C at 4C/min,hold15minInjector temperature: 250C Detector temperatur
27、e: 300CCarrier gas: HeliumLinear velocity: 40 cm/s (Flow rate: 10 cm3/min)ECD sensitivity: 8 3 1011AFSFIG. 4 ECD Septum BleedE 1510 95 (Reappproved 2005)27.1.2 Clean or deactivate, or both, injector and detectorsleeves (if necessary),7.1.3 Replace critical injector and detector seals,7.1.4 Replace s
28、eptum,7.1.5 Set make-up and detector gas flow rates,7.1.6 Carefully inspect the 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 ad
29、ditional 10 cm from each end of the columnto remove ferrule shards,7.1.10 Mount 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,7.1.11 Connect the column to the inlet at the appropriatedistance as i
30、ndicated in the instrument manual,7.1.12 Set the approximate column flow rate by adjustingthe head pressure (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
31、 outlet in a vial ofacetone or methylene chloride,7.1.15 Connect the column to the detector at the appropriatedistance 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
32、 Set injector and detector temperatures and turn ondetector when temperatures have equilibrated (CautionDonot 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
33、 sure dead volumepeak does not tail,7.1.20 Condition the column at the maximum operatingtemperature for 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 confi
34、rm proper installation andcolumn performance, and7.1.23 Calibrate instrument and inject samples.7.2 The following section provides in-depth information oninstrument preparation procedures for installing and operatingfused silica capillary columns in capillary dedicated gaschromatographs:7.2.1 Gas Pu
35、rificationThe carrier gas must contain lessthan 1 ppm of oxygen, moisture, or any other trace contami-nants. Otherwise, oxygen and moisture degrade column per-formance, decrease column lifetime, and increase backgroundstationary phase bleed. Contaminants such as trace hydrocar-bons cause ghost peaks
36、 to appear during temperature program-ming and degrade the validity of the analytical data. Make-upgas should also be contaminant-free or baseline fluctuationsand excessive detector noise may occur. Detector gases such ashydrogen and compressed air should be free of water andhydrocarbon or excessive
37、 baseline noise may occur.7.2.1.1 Install purifiers as closely as possible to the GCsbulkhead fitting, rather 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
38、.2 Only highpurity gases should be used for capillarychromatography. All regulators should be equipped with stain-less steel diaphragms. Regulators equipped with rubber orelastomeric diaphragms should not be used because oxygen,moisture, and elastomeric contaminants migrate through thediaphragm and
39、enter the flow.7.2.1.3 Both indicating and non-indicating traps are avail-able from most capillary column suppliers. 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 th
40、e oxygen trap. Ifhydrocarbon contamination is suspected, a hydrocarbon trapshould be installed between the moisture 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 t
41、he trap, the lineleading to and from the purifier should be coiled to relievestrain and isolate instrument vibrations.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
42、 in length (compared to 2 m for packed columns),a carrier gas that minimizes the effect of dead time isimportant. 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
43、 is programmed from ambient to 300C.Therefore, a carrier gas that retains high efficiency over a widerange of 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
44、cm/s) is greater than all the others, and hydrogenexhibits the flattest van Deemter profile. Helium is the nextbest choice (uopt: 20 cm/s). Note that head pressures atoptimum flow rates are similar for hydrogen and heliumbecause hydrogen has half the viscosity but double the linearvelocity as helium
45、. 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.7.2.2.2 Temperature programming usually provides similaranalysis times between hydrogen and helium since the elutionof mo
46、st 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 carrier gases, such as helium, can improve the separa-tion of very low boiling or early eluting compounds since theyallow
47、 more interaction with the stationary phase. Fig. 5E 1510 95 (Reappproved 2005)3illustrates that hydrogen is only slightly faster than heliumwhen both carrier gases are operated under the same tempera-ture to programmed conditions. Also, note that helium im-proves the resolution of the early eluting
48、 compounds (Peaks 1and 2) as compared to hydrogen for a temperature programmedanalysis.NOTE 1Warning: Exert caution when using hydrogen as a carriergas. Hydrogen is explosive when concentrations exceed 4 % in air andshould only be used by individuals who have received proper training andunderstand t
49、he potential hazards. Proper safety precautions should beutilized to prevent an explosion in the oven chamber. Some gas chromato-graphs are designed with springloaded doors, perforated or corrugatedmetal oven chambers, and back pressure/flow controlled pneumatics,which minimize the hazards when using hydrogen carrier gas. Additionalprecautions used by analysts include:(a) Frequently check for carrier gas leaks using a sensitive electronicleak detector,(b) Use electronic sensors that shut down the carrier gas flow should anexplosive atmosp
