B-305 High Specificity Homogeneous Enzyme Immunoassay for Ketamine
Clinical Chemistry October 1, 2025 Se Yeon Oh, Kim Pham, Rajendra Singh et al.
A new immunoassay, the ARK Ketamine II Assay, accurately detects ketamine in human urine at two cutoff concentrations (50 and 100 ng/mL) with high precision and specificity. In tests on 223 negative urine samples, the assay correctly identified all as negative, including 22 that had produced a response above the detection limit in the earlier version. For positive samples confirmed by LC-MS/MS, the assay showed 100% sensitivity and 100% specificity at both cutoffs. The assay also cross-reacts with the major metabolite nor-ketamine at about 45–47%, while cross-reactivity to methoxetamine is less than 0.3%. The method is suitable for routine clinical chemistry analyzers.