Automation of the Turbidimetric Determination of Serum Lipase

Abstract

A turbidimetric procedure for the determination of serum lipase activity has been adapted for use on a System Olli 3000 analyser. In this automated procedure 50 μl of serum and standard sample, and a buffer solution, are pipetted into disposable cuvettes in the measurement block. The block is then preincubated for 15 minutes at 37°C, and after simultaneous addition of the olive oil emulsion, the absorbances of the cuvettes are recorded simultaneously for two minutes at 405 nm. Using the program ‘block standards’ for the calibration of the method the results are ready in graphic form and expressed as U/l within about five minutes of the addition of the olive oil. A total of 60 patient sera can be analysed in half an hour. The method is linear up to at least 1000 U/l, and the reference values are between 11 and 140 U/l. A comparison of the method with the modification of the Cherry-Crandall titrimetric method gives a value of 0·87 for the correlation coefficient and the regression equation y = 0·97x + 12 (n = 191). Within-run precision (CV) for sera with mean enzyme activities of 149 and 354 U/l was found to be 4·2% and 3·4%, respectively (n = 20), and day-to-day precision 5·0% (mean activity = 339 U/l, n = 18).