Nineteen adulterants commonly encountered in cocaine and heroin exhibits were also analyzed. From these results, guidelines are presented for the determination of residual solvents in both uncut and adulterated exhibits. With a few exceptions (notably "crack" cocaine), virtually all illicit amine-based drugs are prepared and marketed as salts, most commonly as hydrochloride (HCL) salts. Such salts are typically prepared either by adding concentrated HCL acid or by bubbling HCL gas into an organic solution of the respective free base. Both procedures generally result in rapid precipitation, commonly giving crystal matrices that contain significant quantities of occluded (trapped) solvents. These residual solvents may be subjected to rigorous qualitative and quantitative analysis for both strategic and tactical intelligence. In this experiment, the liberalization of the occluded solvents was ensured by complete solubilization of the crystal matrices in aqueous 22 percent sodium sulfate. Ion trap mass spectrometry was used for both identification and quantitation; five deuterated, structurally related internal standards were used for more accurate quantitation. Overall method precision for 25 commonly encountered solvents averaged 6.7 percent RSD. Minimum detection limits ranged from 3 to 87 ppm for a 15 mg equivalent cocaine sample weight, and from 2 to 43 ppm for a 30 mg equivalent cocaine sample weight. Qualitative and quantitative data for the 25 most commonly encountered occluded solvents in cocaine HCL and heroin HCL exhibits are presented. 5 tables, 2 figures, and 24 references