Specific conductivity of urine and sensitivity of enzyme immunoassay methods of analysis for drugs of abuse

Abstract

The authors studied the sensitivity of the EMIT assays of amphetamine, benzodiazepines (diazepam), methadone, opiates (morphine), and propoxyphene at different specific conductivities in urine. The specific conductivity was varied by adding NaCl. For a sensitivity of 0.5 mg of drug per liter, the urine must have a specific conductivity of less than about 35 mS/cm in all these assays except that for benzodiazepine, for which it must be less than about 20 mS/cm.