ELISA Screens for Fentanyl in Urine Are Susceptible to False-Positives in High Concentration Methamphetamine Samples

Abstract

Immunoassay techniques are commonly used for urine drug screening in forensic and clinical toxicology laboratories. While these techniques are excellent for the nonspecific detection of a wide variety of drug classes, their very nature renders them vulnerable to false negatives and false positives.The New York State Police Forensic Toxicology Laboratory investigated a trend of false-positive fentanyl urine drug screens and determined that urine methamphetamine levels greater than 40 μg/mL can cause a false-positive urine fentanyl screening result using the Neogen enzyme-linked immunosorbent assay kit at a 1 ng/mL fentanyl decision point.