Evaluation of an amylase method utilizing p-nitrophenyl glucosides as substrates

An enzymatic method which uses p-nitrophenyl glucosides as substrates for the determination of amylase activity has been evaluated. The kit can be used in either a two point or multiple point mode but these give different results. In both modes the reagent gave a linear response to at least 800 U/I. No interference by endogenous compounds was observed as has been reported with some enzymatic procedures. Within-batch precision (coefficient of variation 1% at 340 U/I and 5% at 10 U/I) and inter-batch precision (coefficient of variation 3.4% at 170 U/I and 3.7% at 56 U/I) are comparable to other amylase methodologies. Correlation with both the manual dye-starch (Phadebas) (r2 = 0.994) and the Beckman Amylase-DS (r2 = 0.998) methods was good for the sera and urines examined. Normal range for serum was 17 to 84 U/I (mean +/- 2 SD). The method is rapid (assay time 10 min), requires very little specimen (20 microliters for the two point assay and 5 microliters for the multiple point assay) and is suitable for both routine and emergency use.