ABSTRACT
BACKGROUND: Monitoring of the concentration of gentamicin in serum and plasma during therapy is widely recommended and practiced in hospitals. Our aim was to develop a homogeneous immunoassay based on particle-enhanced turbidimetric inhibition immunoassay technology to quantify gentamicin on the Dimension clinical chemistry system. METHODS: Assay performance was assessed on each of the Dimension models in a 15-instrument interlaboratory comparison study. A split-sample comparison (n = 1171) was also performed between the gentamicin methods on the Dimension system and the Abbott TDx analyzer, using multiple reagent and calibrator lots on multiple instruments. RESULTS: The Dimension method was linear to 25.1 micromol/L (12.0 microg/mL) with a detection limit of 0.63 micromol/L (0.3 microg/mL). Calibration was stable for 30 days. The within-run imprecision (CV) was <1.3%, and total imprecision ranged from 1.8% to 3.2% between 4.2 micromol/L (2.0 microg/mL) and 16.7 micromol/L (8.0 microg/mL) gentamicin. Linear regression analysis of the results on the Dimension method (DM) vs the Abbott TDx yielded the following equation: DM = 0.98TDx - 0.42; r = 0.987. Minimal interference was observed from structurally related compounds such as sagamicin, netilmicin, and sisomicin. CONCLUSION: The monoclonal antibody used in this method has similar reactivities toward the individual gentamicin subspecies C1, C1a, and C2, thus providing analytical recovery not significantly dependent on relative subspecies concentrations.
Subject(s)
Anti-Bacterial Agents/blood , Gentamicins/blood , Anti-Bacterial Agents/immunology , Antibodies, Monoclonal , Autoanalysis , Gentamicins/immunology , Humans , Immunoassay , Nephelometry and Turbidimetry , Reagent Kits, DiagnosticABSTRACT
A fully automated, random access method for the determination of cannabinoids (UTHC) was developed for the Dimension AR and XL clinical chemistry systems. The method utilizes Abuscreen ONLINE reagents and a multianalyte liquid calibrator containing 11-nor-Delta(9)-THC-9-carboxylic acid. Within-run and total reproducibility, determined using NCCLS protocol EP5- T2, was less than 0.6% and 1.6% CV, respectively, at all concentrations. Calibration stability was retained for at least 30 days. An extensive evaluation of non-structurally related drugs and various physiological substances indicated lack of interference in the method. No sample carry-over was observed following a specimen containing 1886 ng/ml 11-nor-Delta(9)-THC-9-carboxylic acid. A 99.1% agreement (N = 445 samples) was found between an EMIT based method on the aca discrete clinical analyser and the Dimension UTHC method.Dimension clinical chemistry system and aca discrete clinical analyser are registered trademarks of Dade International.
