Determination of Five Abused Drugs in Nitrite-Adulterated Urine by Immunoassays and Gas Chromatography-Mass Spectrometry

Abstract

The adulteration of urine specimens with nitrite ion hasseen shown to mask the gas chromatography-mass spectrometry (GC-MS) confirmation testing of marijuana use. This study was designed to further investigate the effect of nitrite adulteration on the detection of five commonly abused drugs by immunoassay screening and GC-MS analysis. The drugs tested are cocaine metabolite (benzoylecgonine), morphine, 11-nor-delta-tetrahydrocannabinol-9-carboxylic acid (THCCOOH), amphetamine, and phencyclidine. The immunoassays evaluated included the instrument-based Abuscreen ONLINE assays, the on-site Abuscreen ONTRAK assays, and the one-step ONTRAK TESTCUP-5 assay. Multianalyte standards containing various levels of drugs were used to test the influence of both potassium and sodium nitrite. In the ONLINE immunoassays, the presence of up to 1.0M nitrite in the multianalyte standards had no significant effect for benzoylecgonine, morphine, and phencyclidine assays. With a high concentration of nitrite, ONLINE became more sensitive for amphetamine (detected more drug than what was expected) and less sensitive for THCCOOH (detected less drug than what was expected). No effects of nitrite were observed on the results of the Abuscreen ONTRAK assays. Similarly, no effects were observed on the absolute qualitative results of the TESTCUP-5 when testing the nitrite-adulterated standards. However, the produced intensities of the signals that indicate the negative test results were slightly lowered in the THC and phencyclidine assays. The presence of 1.0M of nitrite did not show dramatic interference with the GC-MS analysis of benzoylecgonine, morphine, amphetamine, and phencyclidine. In contrast, nitrite ion significantly interfered with the detection of THCCOOH by GC-MS. The presence of 0.03M of nitrite ion resulted in significant loss in the recovery of THCCOOH and its internal standard by GC-MS. The problem of nitrite adulteration could be alleviated by sodium bisulfite treatment even when the specimens were spiked with 1.0M of nitrite ion. Although bisulfite treatment decomposed all nitrite ions in the sample to recover the remaining THCCOOH by GC-MS, the net recovery of THCCOOH depended on urinary pH and time and conditions of sample storage. The presence of nitrite concentrations that might arise from all possible natural sources, including microorganisms, pathological conditions, and medications, did not interfere with the GC-MS analysis of THCCOOH.

Is this urine really negative? A systematic review of tampering methods in urine drug screening and testing

“…Mixed results have been obtained for nitrite's capacity to produce a false-negative result. One study has demonstrated that nitrite can successfully mask the presence of THC, the cocaine metabolite benzoylecgonine, morphine, amphetamine, and PCP during immunoassay screening procedures (Tsai et al, 1998). This study also found that nitrite will interfere with GC/MS confirmation processes for THC but will not affect this test for benzoylecgonine, morphine, amphetamine, and PCP.…”

Detection and identification of 2‐nitro‐morphine and 2‐nitro‐morphine‐6‐glucuronide in nitrite adulterated urine specimens containing morphine and its glucuronides

“…[2][3][4] Codeine can also be metabolized to morphine in addition to codeine glucuronide to aid excretion from the body. [8][9][10][11] A previous study conducted by the authors has shown that exposure of 6-MAM to nitrite (active ingredient of commercial oxidizing adulterants 'Klear' and 'Whizzies') results in the formation of 2-nitro-6monoacetylmorphine (2-nitro-MAM), rendering the initial 6-MAM analyte in the urine specimen undetectable. [6] Opiates are also being targeted in workplace drug-testing programmes due to their ease of possession and overuse in the community.…”

“…These chemicals have been found to interfere with screening and confirmatory assays and mask certain drugs of abuse, including opiates, in urine. [8][9][10][11] A previous study conducted by the authors has shown that exposure of 6-MAM to nitrite (active ingredient of commercial oxidizing adulterants 'Klear' and 'Whizzies') results in the formation of 2-nitro-6monoacetylmorphine (2-nitro-MAM), rendering the initial 6-MAM analyte in the urine specimen undetectable. [12] Although urine collection protocols are quite strict, particularly in sports drug testing, the act of adulteration is not impossible.…”

2-Nitro-6-monoacetylmorphine: potential marker for monitoring the presence of 6-monoacetylmorphine in urine adulterated with potassium nitrite

“…However, one problem in urine drug testing is adulteration by in vitro oxidizing adulterants. It has been well documented that nitrite (active ingredient of the marketed in vitro urine adulterants 'Klear' and 'Whizzies') amongst other oxidizing chemicals is capable of masking the presence of various drugs in urine in both screening and confirmatory assays [5][6][7][8]. However, there is limited information on the specific effects of nitrite on detection of 6-MAM.…”