NCJ Number
176764
Journal
Journal of Forensic Sciences Volume: 43 Issue: 6 Dated: November 1998 Pages: 1203-1207
Date Published
1998
Length
5 pages
Annotation
The routine sampling method for heroin street doses used in the laboratory in Israel was described and evaluated, based on an analysis of 48 exhibits including about 1,300 street doses that had been sampled and examined in the past.
Abstract
The research was prompted by recognition that new legislation enacted in 1991 allowed acceptance as evidence the identification of the drug and the estimated weight for the total exhibit based on random sampling. Since then, it has become standard procedure in the Analytical Chemistry Laboratory at the Israel Police National Headquarters to open, weigh, and analyze only a part of a larger number of drug street doses, while the indictment is based on the total exhibit. The present study weighed the previously unanalyzed street doses of each exhibit; the true total weight of each exhibit was compared with the original estimated total weight. The relative sampling error of the original estimates was about 5 percent; these tended to be lower than the true weight by about 0.7 percent. Additional random sampling was also performed on the 48 exhibits, creating for each exhibit 4 new samples from the unanalyzed street doses. The additional estimates were compared with the original estimated weight and the true total weight. Heroin was detected in all the previously unanalyzed street doses. Findings indicated that the precision of the actual sampling procedure is satisfactory and matches the statistical theoretical basis. Improvement in the sampling procedure should produce additional accurate acceptable estimates. Tables and 4 references (Author abstract modified)