Simultaneous measurement of fentanyl, fentanyl analogues and other drugs of abuse by multiplex bead assay.

Quantification of illicit drugs and controlled substances, in urine or as surface contamination, is often performed using expensive analytical techniques such as liquid chromatography with tandem mass spectrometry (LC-MS/MS). A time and cost-effective semi-quantitative surface-wipe and urine screening multiplex immunoassay for fentanyl and its analogues was developed in this investigation. We previously created a surface wipe multiplex immunoassay for methamphetamine, caffeine, cocaine, tetrahy-drocannabinol (THC) and oxycodone. This fluorescent covalent microsphere immunosorbent assay (FCMIA) is a competitive assay where drugs compete with protein-drug conjugates attached to microspheres for antibodies. It was assembled using a commercially available fentanyl antibody and protein-conjugate. Surface recovery from ceramic tiles was assessed by FCMIA, with results ranging from 26% for fentanyl to 60% for methamphetamine. Only fentanyl and its structurally similar analogues showed significant response to the fentanyl assay whereas, analogues structurally similar to carfentanil gave no response. Non-fentanyl drug assays did not appreciably detect fentanyl or its analogues. Overall, this method is a useful tool for assessing surface contamination and the effectiveness of decontamination by multiple drugs of abuse, potentially lowering workplace exposures. To broaden applicability, different antibodies or aptamers must be developed to detect structural differences found in classes of analogues such as carfentanil.