Evaluation of a turbidimetric procedure for apolipoproteins A1 and B on the Ciba Corning 550 EXPRESS

We evaluated a turbidimetric method for the estimation of apo A1 and apo B on the Ciba Corning 550 EXPRESS using Ciba Corning reagents. Interference due to bilirubin, hemoglobin, lipemia, triglycerides, and uremia was minimal, with apolipoproteins (apo) A1 and B results usually within +/- 4% of expected values. Within-run and day-to-day imprecision (coefficients of variation) ranged from 1.96 to 3.60% and 2.63 to 3.39% for apo A1 and 1.02 to 1.74% and 2.08 to 3.66% for apo B, respectively. Accuracy was determined by participation in the IFCC apolipoprotein standardization project in which results obtained on 50 patient samples were compared to those obtained by the reference laboratory. Apo A1 and apo B showed an average bias of +3.7% and +2.0% and correlation coefficients of 0.986 and 0.977, respectively. Results were also compared to those obtained on the Behring Turbitime system and showed a bias of +7.5% and -8.8% for apo A1 and apo B, respectively. The Ciba Corning automated method was rapid and gave good accuracy, precision, linearity, and parallelism and was relatively unaffected by raised triglyceride values.