Analysis of lidocaine on the COBAS INTEGRA

A new fluorescence polarization (FP) immunoassay was developed for the COBAS INTEGRA to quantitate lidocaine in serum and sodium heparin derived plasma. The COBAS INTEGRA, a random and continuous access clinical analyzer, performs the new lidocaine assay at a throughput of 300 tests per hour. Comparison studies with the Abbott TDx Lidocaine assay yielded a correlation coefficient of 0.99 and a regression value of INTEGRA = -0.01 + 0.95 TDx, n = 69. The assay was found to be linear throughout the concentration range of 0 to 10 micrograms/ml using CASCO STANDARDS's DOCUMENT TDM 1 Linearity Test Set and the COBAS-FP TDM Calibration Verification Test Set. The new lidocaine assay exhibited good precision as determined by the National Committee for Clinical Laboratory Standards (NCCLS) protocol EP5-T2 with total percent coefficient of variation (%CV) values of less than 4 percent across the assay range. Interference was less than 10 percent for abnormal levels of total protein (2.1 to 10 g/dl), lipid (up to 2200 mg/dl triglyceride), hemoglobin (up to 10 g/dl), and icteric samples (up to 17.5 mg/dl bilirubin). Finally, the standard curve was stable for greater than 25 weeks which was attributable to the on-board reagent cooling and a unique cassette closure system.