Volume 43, Issue 6 (November 1998)
Evaluation of a Sampling Procedure for Heroin Street Doses
New legislation regarding methods of drug sampling was passed in Israel in 1991. According to this law, the qualitative result (i.e., identification of the drug) as well as the estimated weight for the total exhibit, based on random sampling, are applied to the total exhibit and may be accepted as evidence. Since then, it has become standard procedure in the Analytical Chemistry Laboratory to open, weigh and analyze only a part of a larger number of drug steet doses while the indictment is based on the estimated weight of the total exhibit. In this study, the routine sampling method for heroin street doses used in the laboratory is described and evaluated. For this purpose, 48 exhibits, including about 1300 street doses of powder which had been sampled and examined in the past, have been collected. The previously unanalyzed street doses of each exhibit were weighed and the true total weight of each exhibit was compared with the original estimated total weight. The relative sampling error of the original estimates is about 5% and these tend to be lower than the true weight by about 0.7%. Additional random sampling was also performed on the 48 exhibits, creating for each exhibit four new samples from the unanalyzed street doses. The additional estimates have been compared with the original estimated and the true total weight. Heroin was detected in all the previously unanalyzed street doses.