Glutaraldehyde as an Adulterant to Urine

Glutaraldehyde has also been used as an adulterant to mask urine drug tests (39). This product is available under the trade name of "UrinAid." The manufacturer, Byrd Laboratories (Topanga, CA), sells this product for $20-30 per kit. Each kit contains 4-5 mL glutaraldehyde solution, which is added to 50-60 mL of urine. Glutaraldehyde solutions are available in hospitals and clinics as a cleaning or sterilizing agent. A 10% solution of glutaraldehyde is available from pharmacies as over-the-counter medication for treatment of warts. Glutaraldehyde at a concentration of 0.75% volume can lead to false-negative screening results for a cannabinoid test using the EMIT II drugs of abuse screen. Amphetamine, methadone, benzodiazepine, opiate and cocaine metabolite tests can be affected at glutaraldehyde concentration between 1 and 2% using EMIT immunoassays. At a concentration of 2% by volume, the assay of cocaine metabolite is significantly affected (apparent loss of 90% sensitivity). A loss of 80% sensitivity was also observed with the benzodiazepine assay.

Wu et al. (40) reported that glutaraldehyde also interfered with the CEDIA immunoassay for screening of abused drugs. Goldberger and Caplan (41) reported that glutaraldehyde caused false-negative results with EMIT but also caused false-positive phencyclidine results with the FPIA (Abbott Laboratories) and Kinetic Interaction of Microparticles in a Solution Immunoassay (KIMS, Roche Diagnostics).

Although the presence of glutaraldehyde as an adulterant in urine can be detected by GC/MS, Wu et al. described a simple fluorometric method. When 0.5 mL of urine was heated with 1mL of 7.7mmol/L potassium dihydrogen phosphate (pH 3.0) saturated with diethylthiobarbituric acid for 1 h at 96-98°C in a heating block, a yellow green fluorophore developed if glutaraldehyde was present. Shaking the specimen with n-butanol resulted in the transfer of this adduct to the organic layer which can be viewed under long wavelength UV light. Glutaraldehyde in urine can also be estimated using a fluorimeter (42).

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