A new potentiometric sensor for the determination of α-amylase activity.
A platinum redox sensor for the direct potentiometric determination of α-amylase concentration has been described. The sensor measured the amount of triiodide released from a starch-triiodide complex, which was correlated with the α-amylase activity after biocatalytic starch degradation. The composition and stability of the potassium triiodide solution was optimized. The starch-triiodide complex was characterized potentiometrically at variable starch and triiodide concentrations. The response mechanism of the platinum redox sensor towards α-amylase was proposed and the appropriate theoretical model was elaborated. The results obtained using the redox sensor exhibited satisfactory accuracy and precision and good agreement with a standard spectrophotometric method and high-sensitive fully automated descret analyser method. The sensor was tested on pure α-amylase (EC 3.2.1.1, Fluka, Switzerland), industrial granulated α-amylase Duramyl 120 T and an industrial cogranulate of protease and α-amylase Everlase/Duramyl 8.0 T/60 T. The detection limit was found to be 1.944 mU for α-amylase in the range of 0-0.54 U (0-15 μg), 0.030 mKNU for Duramyl 120 T in the range of 0-9.6 mKNU (0-80 μg) and 0.032 mKNU for Everlase/Duramyl 8.0 T/60 T in the range of 0-9.24 mKNU (0-140 μg).
Department of Chemistry, Josip Juraj Strossmayer University of Osijek, Osijek, Croatia. nikola.sakac@gmail.com
Nikola
N
Sakac
Milan
M
Sak-Bosnar
Marija
M
Horvat
Dubravka
D
Madunić-Cacić
Aleksandar
A
Szechenyi
Barna
B
Kovacs
D057230:Limit of Detection; D010084:Oxidation-Reduction; D010984:Platinum / Q000737:chemistry; D011199:Potentiometry; D000516:alpha-Amylases / Q000032:analysis / Q000737:chemistry*
D010984:Platinum; D000516:alpha-Amylases