Limits of detection ranged from 0.6 ng/mL for PCP, to 34.1 ng/mL for benzodiazepines. The average within run and total precision for these assays ranged from 1.3 percent to 7.3 percent for controls at cutoff concentrations, and control values at 125 percent and +25 percent of cutoffs. The rate separations by CEDIA between the negative and cutoff calibrators for all drugs were greater than corresponding EMIT II (Syva Co.) assays. The relative sensitivity and specificity of CEDIA as compared to EMIT II were 95.6 percent and 98.8 percent respectively on 13,535 urine samples. All positive samples and those samples that produced discordant results between the assays were confirmed by quantitative gas chromatography/mass spectrometry (GC/MS). Using SAMHSA cutoff limits and including barbiturates and benzodiazepines at 300 ng/mL, the relative sensitivity and specificity of CEDIA vs. EMIT II were 96.7 percent and 98.8 percent, respectively. The overall sensitivity of CEDIA compared to GC/MS was 98.9 percent with 179 false positives, compared to 96.2 percent with 189 false positives for EMIT II compared to GC/MS. The effect of adulterants added to urine to potentially invalidate screening results was also tested. CEDIA produced strong interferences for most drug assays in the presence of glutaraldehyde, detergent, and high concentrations of bleach and Drano. Minimal or selective interferences were seen with golden seal tea lemon juice, Visine, and low concentrations of bleach and Drano. Essentially no interference was observed with bicarbonate, sodium chloride, and vinegar. 5 tables and 5 references