Flow injection determination of choline in milk hydrolysates by an immobilized enzyme reactor coupled to a selective hydrogen peroxide amperometric sensor.
A choline oxidase (ChO) immobilized enzyme reactor (IMER) prepared by glutaraldehyde coupling of the enzyme on aminopropyl modified controlled pore glass beads is described. The ChO-IMER was coupled, in a flow injection configuration system, to an interference free hydrogen peroxide amperometric sensor based on a Pt surface modified by an overoxidized polypyrrole film. The resulting analytical device responds selectively to choline and displays a sensitivity of 46.9+/-0.2 microC mM(-1) and a limit of detection, calculated at a signal-to-noise ratio equal to 3, of 7 microM. Sensitivity remains constant for about 20 days and then starts to slowly deteriorate and after 2 months a 70% of the initial sensitivity was still retained. The application to choline determination in milk hydrolysates is demonstrated. Short- and long-term drift observed in the analytical response can be corrected by a bracketing technique.
Pati
Sandra
S
Dipartimento di Chimica, Università degli Studi di Bari, Via Orabona 4, 70126 Bari, Italy.
Quinto
Maurizio
M
Palmisano
Francesco
F
D000429:Alcohol Oxidoreductases / Q000737:chemistry; D000818:Animals; D019149:Bioreactors; D002794:Choline / Q000032:analysis*; D004800:Enzymes, Immobilized; D017022:Flow Injection Analysis; D005976:Glutaral / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry; D008892:Milk / Q000737:chemistry*
D004800:Enzymes, Immobilized; D006861:Hydrogen Peroxide; D000429:Alcohol Oxidoreductases; C019888:choline oxidase; D002794:Choline; D005976:Glutaral