Effects of oral fluid contamination on two oral fluid testing systems.

Oral fluid is a popular matrix for drug testing; however, little has been published concerning the effect that food or beverages may exert on oral fluid screening tests. This study describes the effects of 19 different foods, beverages and vinegars on two test systems, the Concateno Certus and Orasure Intercept. Samples giving positive screening results were subjected to confirmatory analysis using gas chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry. Results showed that intermittent presumptive positive results for amphetamine, methadone, opiates and cocaine could be detected following the consumption of coffee, Coke, fruit juice, oranges, spicy food and toothpaste using the Orasure system if specimens were not collected in accordance with the manufacturer's recommended collection procedure. Following the consumption of vinegar, presumptive positives were observed using the Orasure system for up to 30 min post-exposure. No presumptive positives were observed using the Concateno system. It is a widely held view that foods and beverages disperse from the mouth within 10-15 min after their consumption, and hence are unlikely to affect oral fluid drug tests. This study shows that vinegar can affect immunoassay screening for an extended period following its consumption.