Comparison of two gas saturation methods for the determination of the vapour pressure of cypermethrin

Abstract

The vapour pressures of cypermethrin have been determined independently, at elevated temperatures in two different laboratories, by different versions of the gas saturation method. A subsequent statistical analysis showed no significant differences between the two sets of data. The mean of the values, extrapolated to 20°C, is 1.9 × 10−7 Pa (1.4 × 10−9 mmHg). A description of one of the methods, previously unpublished, is included as an appendix.

Estimation of vapor pressures for nonpolar organic compounds by capillary gas chromatography

“…Precisions of a few percent are attainable in a single laboratory, but agreement among laboratories is less satisfactory. In one study (23) two independent gas saturation values for a pyrethrin insecticide agreed within 45%. However, during an OECD intercalibration exercise on physicochemical properties determinations (22) agreement between saturation and effusion values for benzoic acid, hexachlorobenzene, and di-2-ethylhexyl phthalate was no better than a factor of 2-3.…”

Reviews of Environmental Contamination and Toxicology

“…Vapor Pressure. Grayson et al (1982) employed a gas saturation technique to measure cypermethrin vapor pressure and measured the value shown in Table 33. Alvarez also used a gas saturation technique to measure the vapor pressures of cypermethrin (l991b) and zetacypermethrin (1991a) at 25°C so that no extrapolation from vapor pressure at higher temperature was necessary.…”