A potential high-throughput method for the determination of lipase activity by potentiometric flow injection titrations

Potentiometric FIA titrations were performed to determine enzyme activities of lipase type B from Candida antarctica, CAL-B. Two substrates, triacetin and tributyrin were hydrolyzed in phosphate buffer solutions, and the concentration change of the base component of the buffer was titrated in a carrier solution containing hydrochloric acid and potassium chloride. The system was calibrated with butyric acid and acetic acid, respectively. FIA titration peaks were evaluated with respect to peak height and peak area. Butyric acid and acetic acid could be titrated in the buffer solution from 3 × 10⁻³ mol L⁻¹ to 0.1 mol L⁻¹. The detection limit of enzyme activity was determined to be 0.07 U mL⁻¹ (15 min reaction time) and the minimum activity was calculated to be 0.035 units corresponding to 35 nmol min⁻¹. The specific activities of lipase B for the hydrolysis of tributyrin and triacetin were determined as 16 ± 2 U mg⁻¹ and 2 ± 0.2 U mg⁻¹ (per mg commercial lipase preparation), respectively.