Comparison of Drugs of Abuse Detection in Meconium by EMIT® II and ELISA

The results of meconium specimens and fortified samples screened for drugs of abuse by both enzyme multiplied immunoassay technique (EMIT® II) and enzyme-linked immunosorbent assay (ELISA) methods were compared. The sample preparation for the ELISA screen was a simple buffer extraction versus a lengthy and more laborious sample preparation procedure for the EMIT II screen. The ELISA method was automated using a TECAN Genesis. The EMIT II analysis was automated with an Olympus AU400e. The opioid screen was calibrated with hydromorphone and the benzodiazepine screen was calibrated with clonazepam to maximize detection for these analytes. Previously validated gas chromatography-mass spectrometry (GC-MS), two-dimensional GC-MS, or liquid chromatography-tandem MS methods were used for confirmation. Results from the two techniques compared well. Agreement of the ELISA assay was greater than 90% when compared to EMIT II for all drug classes except barbiturates and benzodiazepines. ELISA appears to be more sensitive than EMIT II for the detection of amphetamines, methadone, propoxyphene, and cocaine. ELISA compared well to EMIT II for cannabinoids, opioids, and PCP. Specificity of the ELISA assay was slightly better for PCP and opioids. EMIT II appears to be more sensitive for the detection of barbiturates and benzodiazepines. The ELISA method reduced turnaround time by 50% compared to the EMIT II method.