Optimization of Storage Conditions for Cocaine and Benzoylecgonine in Urine: A Review

The maximum stability conditions for cocaine and its metabolite benzoylecgonine (BE) in urine were analyzed. Suggestions were presented after careful review of many studies and personal communications concerning cocaine and BE stability in urine. The optimal storage conditions for urine specimens with cocaine and BE were determined to be at -15~ and a pH of 5.0. Ascorbic acid was found to be a favorable agent to attain this acidic pH. Unsilanized glass was determined to be a favorable container material. Storage in darkness was also supported. Storage of urine specimens under these conditions was believed to prevent degradation of cocaine and benzoylecgonine for at least 110 days,