Immunoassay screen for qualitative detection of alcohol in urine.

Ethyl Glucuronide (ETG) is a direct metabolite of ethanol, formed by enzymatic conjugation of ethanol with glucuronic acid. Alcohol in urine is usually detected for only a few hours, whereas ETG can be detected for up to several days after complete elimination of alcohol from the body. The DRI ETG screen in an enzyme immunoassay.

The assay uses specific antibodies that can detect Ethyl Glucuronide without any significant cross-reactivity to other glucuronide compounds. The assay is based on competition between a drug labeled with glucose-6-phosphate dehydrogenase (G6PDH), and free drug from the urine sample for a fixed amount of specific antibody binding sites. In the absence of free drug from the sample, the specific antibody binds the drug labeled with G6PDH and causes a decrease in enzyme activity. This phenomenon creates a direct relationship between the drug concentration in urine and enzyme activity. Active enzyme converts NAD to NADH resulting in an absorbance change that can be measured spectrophotometrically at 340 nm.