Continuous photometric measurement of lipase activity with the substrate triolein.

Triolein (free from oleic acid) is emulsified in a solution of calcium /v-nitrophenolate with the aid of Thesit or Sterox-SE. As a measure of enzyme activity, the decrease in extinction in the emulsion, which is proportional to the hydrogen ion concentration, is measured continuously at 436 nm with a light path of 0.5 cm. The reaction temperature is 25°C and the time of measurement is 10 min. The determination is performed as a single reagent test on the microlitre scale. The normal range of serum lipase activity lies within the methodical error (< 50 U/l).