Naslov
Sensitive amperometric oxalate biosensor for food analysis

Autori
Milardović, Stjepan ; Grabarić, Zorana ; Grabarić S. Božidar

Izvornik
Food Technology and Biotechnology (1330-9862) 38 (2000); 203-210

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Amperometric biosensor. Graphite electrode modified with nickel. Iron. Ruthenium. Hexacyanometallate. Oxalate

Sažetak
An oxalate biosensor developed by covalent immobilisation of oxalate oxidase enzyme on the top of ruthenium, nickel and iron hexacyanometallate (Ru-FeNiHCM) modified graphite electrode is described. It was noticed that the addition of ruthenium to FeNiHCM layer results in better catalytic efficiency for reduction of hydrogen peroxide at pH=2. To obtain the optimal response of biosensor the influence of several experimental parameters in batch mode, such as working potential, pH and linear concentration range, was examined. Enzymatically produced H2O2 was measured at -50 mV vs. Hg / Hg2Cl2 / 3 M KCl electrode in succinic buffer (pH=3.6). The linear concentration range was up to 100 mu M with squared correlation coefficient R-2=0.9985. Sensitivity of biosensor in this range was 43.2 nA/(mu M cm(2)). Oxalate was determined in real samples of spinach after extraction in water, EDTA and HCl and in samples of different brands of beer. During 11 weeks biosensor sensitivity decreased only 15 % of the initial sensitivity, which means that the biosensor lifetime is much longer than three months.

Izvorni jezik
Engleski

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