Full Description

1.1This practice covers the installation and maintenance of fused silica capillary columns in gas chromatographs that are already retrofitted for their use. This practice excludes information on:

1.1.1Injection techniques.

1.1.2Column selection.

1.1.3Data acquisition.

1.1.4System troubleshooting and maintenance.

1.2For additional information on gas chromatography, please refer to Practice E260. For specific precautions, see 7.2.2.2(1), 7.2.2.2(2), 7.2.7, and 7.2.7.2.

1.3The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.4This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific safety information, see Section 6, 7.2.2.2(1), 7.2.2.2(2), 7.2.7, and 7.2.7.2.²

TABLE 1 Typical Splitter Vent Flow Rates (50 to 1 split ratio) (at optimum linear velocity)

Carrier gas	0.25-mm ID, cm /min	0.32-mm ID, cm /min	0.53-mm ID, cm /min
helium hydrogen	35 70	80 160	125 250

Note 1-The curves were generated by plotting the height equivalent to a theoretical plate (length of column divided by the total number of theoretical plates, H.E.T.P.) against the columns average linear velocity. The lowest point on the curve indicates the carrier gas velocity in which the highest column efficiency is reached.Note 2-Gases information available from Compressed Gas Association (CGA), 4221 Walney Rd., 5th Floor, Chantilly, VA 20151-2923, http://www.cganet.com.FIG. 1Van Deemter Profile for Hydrogen, Helium, and Nitrogen Carrier Gases

Carrier gas: Hydrogen	Carrier gas: Helium
Linear velocity: 40 cm/s	Linear velocity: 20 cm/s

Note 1-Fig. 2 shows that the resolution is similar but the analysis time is reduced by 50% when comparing hydrogen to helium in an isothermal analysis using optimum flow velocities.Note 2-Hydrogen provides similar resolution in one-half the analysis time of helium for an isothermal analysis.Note 3-

	1.Tetrachloro-m-	8.Heptachlor epoxide	15.Endosulfan II
	xylene	9.-chlordane	16.DDD
	2.-BHC	10.Endosulfan I	17.Endrin aldehyde
	3.-BHC	11.-chlordane	18.Endosulfan sulfate
	4.-BHC	12.Dieldrin	19.DDT
	5.-BHC	13.DDE	20.Endrin ketone
	6.Heptachlor	14.Endrin	21.Methyoxychlor
	7.Aldrin

Note 4-30 m, 0.25-mm ID, 0.25 m 5% diphenyl95% dimethyl polysiloxane 0.1-L split injection of chlorinated pesticides.

	Oven temperature: 210C isothermal
	Injector and detector temperature: 250C/300C
	ECD sensitivity: 51210 11
	Split vent: 100 cm 3 /min

FIG. 2Hydrogen Versus Helium (Isothermal Analysis)
FIG. 3 Capping Silanol Groups with Dimethyl Dichlorosilane (DMDCS)
Note 1-Septum bleed can obscure or co-elute with compounds of interest, thus decreasing the analytical accuracy.Note 2-

	1.2,4,5,6-tetrachloro-	8.Heptachlor	16.p,p-DDD
	m-xylene (IS)	epoxide	17.Endrin aldehyde
	2.-BHC	9.-chlordane	18.Endosulfan sul-
	3.-BHC	10.Endosulfan I	fate
	4.-BHC	11.-chlordane	19.p,p-DDT
	5.-BHC	12.Dieldrin	20.Endrin ketone
	6.Heptachlor	13.p,p-DDE	21.Methyoxychlor
	7.Aldrin	14.Endrin	22.Decachlorobi-
		15.Endosulfan II	phenyl (IS)

Note 3-30 m, 0.53-mm ID, 0.50 m 5% diphenyl95% dimethyl polysiloxane 0.1 L direct injection of 50 pg pesticide standard.

Oven temperature: 150 to 275C at 4C/min, hold 15 min
Injector temperature: 250C	Detector temperature: 300C
Carrier gas: Helium
Linear velocity: 40 cm/s (Flow rate: 10 cm 3 /min)
ECD sensitivity: 810 11 AFS

FIG. 4ECD Septum Bleed

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Published: 01/01/2013 Number of Pages: 13 File Size: 1 file , 250 KB