Author: Gary J. Laughlin, Ph. D.
The ideal microanalytical method for forensic drug analysis is an automated procedure operable by a technician covering all known drugs.
Light microscopy and microcrystal tests have been in use for more than 100 years, but are not often regarded as a modern or ideal method. However, they are useful when the automated equipment is not available or when one wishes to check for the presence of one or several specific drugs.
While laboratories may lack analytical capabilities, most still have microscopes and microscopists with proper training. If the analyst wishes to know whether a specific drug is present, the polarized light microscope will answer this question very quickly and rather inexpensively.
The purpose of this project was to compile a comprehensive compendium of microcrystal testes which have previously been developed for illicit drugs and diverted pharmaceuticals.
Although the microcrystal tests analyzed in this project are all well-known and documented, the optical properties of the resulting microcrystals have never been documented. While the main goal of this research was to compile the microcrystal tests into one convenient compendium, another objective was to use the polarized light microscope to acquire new data about these crystals after they were formed. This information will help in their identification, as well as increase the confidence of the analyst in declaring a positive versus a negative result.
Microcrystal tests for the analysis of controlled substances provide a fast, reliable, and inexpensive method of identifying substances. However, in instances where an established microcrystal test is not known by the lab or analyst, the ramifications can be far reaching.
Microcrystal tests have a number of positive attributes to recommend their use in any laboratory. Highlighting these uses should encourage crime laboratories to employ microchemical tests whenever possible.
Having all of this data available in one place in the compendium is convenient and will save forensic scientists a lot of time. Not only are the tests simply described together with many photomicrographs, the reagents and their recipes are easy to understand and prepare. This is a significant improvement since many were convoluted and cryptic when described in the original texts.