The effects of zinc sulfate on ethyl glucuronide immunoassay urine testing
Cawley, Shanna Marie
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Published research in the Journal of Analytical Toxicology and the American Society for Clinical Pathology has confirmed that the presence of Zinc Sulfate in adulterated urine samples can influence the testing results using EMIT and ELISA immunoassay testing when testing for Cannabinoids (THC), Cocaine (Benzoylecgonine), Methamphetamines, Opiates (Morphine, Methadone, and Propoxyphene), Phencyclidine (PCP), and Ethanol (Alcohol Dehydrogenase). This research included adding Zinc Sulfate directly to urine samples. In 2006, the Substance Abuse and Mental Health Service Administration (SAMHSA) released an advisory that the use of Ethyl glucuronide (EtG) as a new biomarker as an indicator for the past-use of alcohol was promising and warranted more research. Ethyl glucuronide is a direct metabolite of the biotransformation of ethanol in the human body. This compound is excreted in urine and can be used as a specific biomarker for the ingestion of alcohol. Because EtG is only produced when ethanol is metabolized, there are no false positives due to fermentation and a much longer detection window exists for its detection. Scientific literature states that EtG can be present in urine long after ethanol has been eliminated. Testing for EtG is commonly referred to as the “80 hour test” for the ability of EtG to be measured up to 80 hours after consuming alcohol. It was hypothesized that if the presence of Zinc Sulfate added to urine falsely reduced urine alcohol level when measuring for Alcohol Dehydrogenase enzyme, will the presence of Zinc Sulfate added to SurineTM falsely reduce the urine alcohol level when measuring for EtG? Since it is very likely that EtG would still be present in the body after ethanol has been eliminated, samples contained either no ethanol or 5% (5g/dL) of ethanol. Samples were spiked at 10mg/mL, 15mg/mL or contained 0mg/mL of Zinc Sulfate. Additionally, duration testing was conducted to see if there was any observed differences between testing the samples fresh and then after a one week duration in a refrigerator and brought to room temperature prior to testing. Two different immunoassay EtG tests were used to perform the analysis. It was concluded that Zinc Sulfate directly added to the sample affected one of the immunoassay test regardless of whether EtG or ethanol were present, by fading the Test and Control regions. Additionally, it is concluded that SurineTM samples containing Zinc Sulfate could easily be distinguished from samples free of Zinc Sulfate because of the presence of a white cloudy precipitate.