A gas-chromatographic determination of organohalogen impurities in dichlorofluoromethane

Abstract

A gas-chromatographic method for the quantitative determination of small amounts of organohalogens in dichlorofluoromethane has been developed, by using a modified flame-ionisation gas chromatograph fitted with columns composed of silicone oil supported on diatomaceous silica. Relative retention times have been determined for a range of organohalogen compounds, together with the sensitivity of the ionisation detector system to each compound. Samples for analysis can be injected into the column by using either a gas syringe or a gas sample valve; the coefficient of variation for dichlorofluoromethane was 9·17 and 0·71 per cent. when using the syringe and gas valve, respectively. Although less precise, injection of the sample by using the syringe has the advantage that smaller samples can be analysed. The time taken to complete a full analysis of a single sample is about 30 minutes.