The pH-detection of triglycerides

This paper presents an indirect method of triglycerides determination based on pH-detection. The system consisted of a microreactor containing silica gel beads with surface immobilised lipase and the pH-sensor of ISFET type. Three methods of lipase immobilisation: (1) the chemical bond to the surface of glass beads coated with keratin, (2) entrapment within alginate gel beads and (3) adsorption onto nitrocellulose sheets were compared. All methods of lipase immobilisation, except the second one, were found to be effective. The systems consisting of microreactors packed with surface immobilised lipase were calibrated for different substrates. The highest sensitivity was obtained for tributyrin (0.478 pH/mM for concentration <4 mM), while the widest linear range was obtained for triacetin (up to 30 mM). The results concerning the influence of some factors, such as activators, and emulgators upon the sensor response are also presented.