The storage of forensic urine drug specimens as dry stains: recovery and stability

Abstract

The feasibility of storing forensic urine drug specimens as dry stains on Whatman #3 paper was studied by evaluating the stability of the drugs and recovery from the stains. Drug stains prepared from urine (3 mL) were stores at -20 degrees C, 4 degrees C, and at room temperature for a period of 12 weeks. The study included: amphetamine, benzoylecgonine, 11-nor-delta-9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH), morphine, and phencyclidine (PCP) as examples of the HHS regulated drug classes. Drugs were eluted from the stains as follows: methanol:saline (1:1) for PCP and THC-COOH, saline for benzoylecgonine and carbonate/bicarbonate buffer pH 9.2 for amphetamine and morphine. Stains were eluted from the support matrix (Whatman #3 filter paper), extracted and analyzed by gas chromatography/mass spectrometry. All drugs were stable under all of the storage conditions except the THC-COOH urine stain stored at room temperature that degraded to zero after 12 weeks. Therefore, drug stains when kept frozen or refrigerated appear to provide a viable means for storing positive urine specimens.