ASTM D4059 Test Method forAnalysis of Polychlorinated Biphenyls in Insulating Liquids by Gas Chromatography
8. Chromatograph Operation Conditions
8.1 General - The characteristics of individual chromatographs and columns differ. Particular operating conditions should be chosen so as to give the separations shown in Fig. 1, Fig. 2, and Fig. 3 for Aroclors 1242, 1254, and 1260. Retention times of the peaks should be determined relative to 1,1' bis (4-chlorophenyl) ethane (p,p'-DDE) to identify the individual peaks with those shown in the chromatograms and listed in the tables. General ranges of temperatures and flow rate with which satisfactory separations have been obtained are listed.
8.2 Column Temperature - Isothermal temperatures between 165 and 200°C have been found suitable when using packed column (see Fig. 1). Temperature programming of megabore columns over the range of 165 to 300°C has been found to enhance resolution and decrease the analytical run time, while generating a chromatogram suitable for use with the packed column GC/MS data (see Appendix X4).
NOTE 2 - Typical chromatographic conditions for a temperature programmed mega-bore capillary column are included in Appendix X4 with the sample chromatograms.
8.3 Detector Temperature - Control the detector isothermally above the maximum oven analysis temperature. A suitable temperature is typically between 280 and 400°C. Follow instrument manufacturer's instructions to prevent exceeding the maximum allowable temperature for the radioactive foil.
8.4 Injection Port Temperature - Maintain the injection port isothermally above a minimum of 250°C.
8.5 Carrier Gas - Ultrahigh purity 5 % methane-95 % argon mixture (P-5) or nitrogen shall be utilized for packed column chromatography. Optimum performance for megabore/capillary columns is achieved with ultrahigh purity hydrogen or helium as the carrier gas and P-5 or nitrogen for detector makeup. A device that will remove oxygen and water vapor from the carrier gas should be used in order to maximize detector sensitivity.
8.6 Flow Rates - Column flow rates of 8 to 60 mL/min and, if used, a detector makeup flow of 15 to 30 mL/min have been found satisfactory. When hydrogen or helium are used as a carrier gas, a makeup flow two to three times the carrier flow will be required to obtain sufficient detector sensitivity.