Determination of cocaine and heroin vapor pressures using commercial and illicit samples

The establishment of drug vapor pressure values provides valuable information in the development of vapor sensing devices for drug detection. The purpose of this work was to determine equilibrium headspace vapor pressures for commercial and illicit drug samples for use in such applications. Samples of cocaine, both free base and hydrochloride forms, and heroin hydrochloride were evaluated. The procedure used to measure the vapor pressures was a modification of a previously published method. Vapor pressure values at 20 °C previously reported for cocaine free base range from 0.37 x 10^-7 to 1.20 x 10^-7 Torr. The vapor pressure value determined in this study was 2.96 x 10^-7 Torr. It is likely that the discrepencies are due to differences in experimental conditions, varying sources of samples, and uncertainty in the methodologies. When the values were compared for commercial (99% purity) and illicit (unknown purity) sources of cocaine free base, there were no statistical difference in the projected room temperature (20 °C) vapor pressure values. However, the commercial and illicit samples of cocaine hydrochloride did show statistical differences. Although no comparison was made with the vapor pressure values for a pure, commercial sample, the vapor pressures of heroin hydrochloride (81% purity) at various temperatures were determine using the method developd for cocaine and are reported in this paper.