RESUMEN
We evaluated the performance of Emit(®) II Plus 6-Acetylmorphine Assay for human urine screening on the Viva-E(®) analyzer. Precision was evaluated using the cutoff and ±25% controls. Recovery and linearity were studied by spiking 6-acetylmorphine (6-AM) into human urine pools. Accuracy was evaluated using urine specimens and the results were compared to those from GC/MS. Cross-reactivity with structurally related drugs was assessed at different cross-reactant concentrations. Interferences were assessed in the presence of 7.5 and 12.5 ng/mL of 6-AM. The qualitative repeatability coefficients of variation (CV's) ranged from 0.3% to 0.4% and the within-lab CV's ranged from 2.0% to 2.2%. In analyte units (ng/mL), the repeatability CV's ranged from 1.3% to 2.2% and the within-lab CV's ranged from 2.6% to 4.3%. The limit of detection of the assay was found to be 2.1 ng/mL. Recovery was within 15% of expected value. Linearity was 2.1-20 ng/mL. Method comparison showed 99% agreement with GC/MS. The assay had minimal cross-reactivity with morphine, morphine-3-glucuronide, morphine-6-glucuronide and other opioids. No interference was observed with endogenous interferences and structurally unrelated drugs. The assay correctly classified CAP survey samples. The Emit(®) II Plus 6-Acetylmorphine Assay will be a suitable screening method for urine specimens in both qualitative and semi-quantitative analyses.