[Change of calibration method for enzyme assay in clinical biochemistry using automatic analyzer--comparison of...

Enzyme activities in serum from experimental animals had been assayed by HITACHI 7150 Automatic Analyzer using K factors for calibration. Because K factor is derived from a molar extinction coefficient and, reagent and sample volumes for each assay system, it is a constant value in usual assay. As an alternative calibration method, a human standard serum, which is commercially available and well-controlled, is presently used in the same assay system because of some difficulties in supply. Four serum enzymes of human, rat, dog and monkey sera were determined by the above two methods. All values calibrated by human standard serum were approx. 10% higher than that using K factors. These small differences are allowable because data calibrated by human standard serum can be compared with previous data given by K factors.