Effect of urine adulterants on commercial drug abuse screening test strip results

Abstract

Immunochromatographic strips for urine drug screening tests (UDSTs) are common and very suitable for drug abuse monitoring, but are also highly susceptible to adulterants kept in the household, which can significantly alter test results. The aim of this study was to see how some of these common adulterants affect UDST results in practice and whether they can be detected by sample validity tests with pH and URIT 11G test strips. To this end we added household chemicals (acids, alkalis, oxidizing agents, surfactants, and miscellaneous substances) to urine samples positive for amphetamine, 3,4-methylenedioxymethamphetamine (MDMA), tetrahydrocannabinol, heroin, cocaine, or benzodiazepines (diazepam or alprazolam) and tested them with one-component immunochromatographic UDST strips. The UDST for cocaine resisted adulteration the most, while the cannabis test produced the most false negative results. The most potent adulterant that barely changed the physiological properties of urine specimens and therefore escaped adulteration detection was vinegar. Besides lemon juice, it produced the most false negative test results. In conclusion, some urine adulterants, such as vinegar, could pass urine specimen validity test and remain undetected by laboratory testing. Our findings raise concern about this issue of preventing urine tampering and call for better control at sampling, privacy concerns notwithstanding, and better sample validity tests.

Advances in testing for sample manipulation in clinical and forensic toxicology - Part A: urine samples

“…Overall, acids, especially vinegar, showed to be a potent adulterant for the investigated test strip system, leading most of the time to negative screening results. The cannabinoid test was more susceptible to sample adulteration than the cocaine test [ 23 ].…”

“…The possibility of detecting sample adulteration with household chemicals by a general biochemical urine test strip system was also investigated by Rajsic et al This study used a test strip system covering pH, specific gravity, nitrite, and ketones, but also more specific compounds such as ascorbic acids, glucose, protein, bilirubin, urobilinogen, blood, and leukocyte cells. Five out of nine adulterations were detected by the system, mainly by pH value or by an “invalid” result from another test field, such as “protein.” The authors concluded that SVT should not only be performed by biochemical tests but also by visible inspection and warmth of the collected sample [ 23 ].…”