The impact of several urine adulterants on samples that test positive for Tetrahydrocannabinol using screening tests

Abstract

Background: Adulteration, a process that involves manipulating a urine specimen with chemical adulterants to obtain a false negative test result, is one of the biggest problems with urine drug testing. Objective: Assessment of effects of some adulterants on urinary drug testing of tetrahydrocannabinol (THC), comparing effects on two screening methods immunoassay and Thin layer chromatography (TLC). Methods: urine samples first were test positive for THC by GC/MS in the toxicology lab at Beni-Suef University. THC positive urine samples were then adulterated by water, HCL bleach, 5% acetic acid, and Tetrahydrozoline eye drops at different concentrations. Finally urine samples were reevaluated for THC using 2 immunoassays, and TLC also, urinary PH, specific gravity, and creatinine and nitrites were assessed then. Results: The PH of urine significantly decreased after being adulterated with 5% acetic acid at concentrations of 10 and 40, highly significant rise in the PH following 40% Tetrahydrozoline, 10% and 40% HCl bleach and after 300% water dilution. Neither 5% acetic acid nor Tetrahydrozoline at concentration 10 had any impact on urine creatinine levels. HCL-based bleach at concentration 40 and twofold water dilution caused the largest, most significant drop in specific gravity. Except for HCL-based bleach, which included nitrates in 100% of cases at a concentration of 40 and in 76.7% of cases at a concentration of 10, no nitrates were detected in urine samples before the addition of adulterants. Overall accuracy is the best for VIVA E except in HCL bleach at 40% and water dilution by 300%, TLC is better. These results showed that VIVA E overall accuracy is better than other methods comparing to GC/MS as gold standard for THC before adding adulterants. Conclusions: HCl bleach caused the most remarkable changed to urine parameters. VIVA E overall accuracy is better than other methods comparing to GC/MS.