Recovery of several volatile organic compounds from simulated water samples: effect of transport and storage

Solutions of volatile organic compounds in organic free water and in 2 per cent methanol were submitted to two U.S. Geological Survey laboratories for volatile organic analysis by gas chromatographic separation and mass spectrometric detection. After 3 days, the analytical recovery of dilute concentrations of bromoform, dichlorobromomethane, ethylbenzene and 1,1,2,2-tetrachloroethane was not statistically different from the recovery of these compounds from methanol solutions which had been kept 100 times more concentrated until immediately prior to analysis. There was no significant difference between values reported by the two laboratories despite an altitude difference of 1.6 km and use of different instruments. Recovery efficiency was more than 80 per cent in more than half the determinations. The recoveries of bromomethane and vinyl chloride were hindered by addition of 2 per cent methanol to the storage containers. Recovery of 2-chlorovinylether from the 2 per cent methanol was greater than from distilled water. However, recoveries from both decreased after 5 days. Recovery of dichloropropene from distilled water decreased after 11 days. There was no significant decrease in the recovery of bromomethane, chlorobenzene, chloroethane, dichlorobromomethane, ethylbenzene and vinyl chloride after 34 days.