Determination of lipase activity by gas chromatography

A rapid gas chromatography method was developed for determination of lipase activity using  tributyrin as substrate.  The standard curves of butyric acid hydrolyzed from tributyrin were linear in the range of 0.11-11.35 mmol·L^-1.  The recoveries of low, moderate and high concentrations of tributyrin were 90.3%, 104.6%, 89.4% with RSD of 3.01%, 4.50%, 6.64%, respectively.  The incubation time was only 5 minutes which was less than with the half time of the conventional titrimetry and spectrophotometry.  The optimum pH value was 7.5 and the optimum temperature was 32 °C.  Based on the Linweaver-Burk plots, the Michaelis- Menten constant was 0.25 mmol·mL^-1.  The effect of orlistat on the enzyme inhibiting activity was studied to prove the accuracy of this method.  It was found that the half-inhibition concentration (IC₅₀) of orlistat was 0.048 5 mg·mL^-1.  The small total reaction volume, the simple treating procedures, the high accuracy and precision present the advantages of the new method.