Potential adulterating capabilities of commercial zinc products on preliminary immunoassay screenings for the detection of ethyl glucuronide (ETG)

Alcohol has been consumed over many centuries, but its connection to criminal activity and accidental fatalities has become a prominent concern in more recent centuries(1). Scientists have developed numerous testing methods to detect alcohol consumption. Numerous studies have recently suggested that zinc has the potential to interfere with the results of these testing methods for drugs of abuse such as enzyme-linked immunosorbent assay (ELISA) and enzyme multiplied immunoassay technique (EMIT) (2, 3). False negatives have been reported from urine testing of drugs such as cocaine, methamphetamine, opiates, and cannabinoids. Nevertheless, minimal research has been conducted concerning zinc’s effect on the adulteration of alcohol metabolite testing. Ethyl glucuronide (EtG) is a promising ethanol metabolite for the confirmation of alcohol consumption. Previous research conducted by Shanna Cawley, a graduate from the Boston University School of Medicine’s Biomedical Forensic Sciences program, has found that zinc sulfate is ineffective at producing conclusive false negative results using two immunochromatographic assay brands in synthetic urine solutions(4). This study uses five different immunoassay brands, five different zinc sources, and two distinct matrices to determine the effectiveness of commercial zinc products as adulterants in drugs of abuse testing. Zinc and EtG solutions were produced at concentrations of 15mg/mL and 750ng/mL, respectively. A positive control, negative control, and two to three experimental trials were conducted for each immunoassay brand and each zinc source resulting in a total of 165 tests. Approximately sixty experimental trials in synthetic urine were invalidated or positive for the presence of EtG (81%) in zinc adulterated EtG solutions. Immunoassay kits produced false positive results when testing human urine from subjects who abstained from alcohol consumption Therefore, preliminary immunoassay screenings for the presence of EtG are not a reliable method for confirming alcohol consumption. Previously researched methods, ELISA and EMIT, and confirmatory methods such as gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) are currently the most robust and reliable techniques for EtG detection in urine