Urine toxicological screening method using an immunoenzymatic assay based on a biochip array technology: comparative study with immunochromatography and Liquid chromatography–mass spectrometry

Multiparametric toxicology research is mainly based on immunochromatography [IC] and chromatography methods. A new automated method using an immunoenzymatic (IE) assay based on a biochip array technology combines short turning around time and analytical performances close to chromatography in terms of positivity cut-off. The aim of our study was to compare IE versus IC and chromatography methods using urines samples from clinical cases. Seventy-two samples were analyzed by IC (amphetamines, opiates, benzodiazepines, THC, methadone, cocaine), IE and chromatography (previous classes plus opioids and cathinone). Immunochromatography results were read by at least 7 operators to assess reading subjectivity. Immunoenzymatic, IC, and chromatrography results were compared with each other. Chromatographic quantification was analyzed to understand discrepancies. Significant discrepancies (29-64%) were observed between IC and IE for most of the drug families investigated except for benzodiazepines, methadone and opiates. These discrepancies were not identified between IE and chromatography, except for some substances (28% to 67% discrepancies for buprenorphine, tramadol and oxycodone, 100% for cathinone). In contrast to IC, the performance of IE approached those of chromatography, except for some substances for which cross-reactions must be investigated. Reading discrepancies were frequent with IC (33% of samples) and made robust result output challenging. In conclusion, the Multistat® is an interesting method for first-line toxicological screening for laboratories without chromatography method.