Although the DAC has been used in many forensic science laboratories for the analysis of trace evidence, few applications of this technique for the analysis of controlled substances have been reported. This may be due both to forensic drug chemists' unfamiliarity with this accessory and the nature and quality of spectra that result from use of a DAC on a dispersive instrument. Along with low-energy throughput, which results in relatively high noise levels, strong broad diamond absorption occur. With the use of a Fourier transform infrared instrument, these do not present a problem, and monogram quantities of materials can be analyzed when the DAC is used with an infrared microscope. Since single crystals can be sampled with the DAC, simple physical separations that involve particle-picking can be used in certain cases to isolate drugs from particulate mixtures for infrared analysis. This method is especially useful for some "difficult" mixtures and residues. Several examples of such analyses that involve samples of forensic science interest are presented. 11 figures and 39 references