Such analytical systems are often expensive and presents short lifetime limited to special conditions of preservation of the enzyme incorporated into the biosensor. An enzyme-free electrochemical sensor was reported for the determination of H2O2 based on a Prussian-blue modified electrode coated with a Nafion polymer layer (Ping et al., 2010). Due to the high selectivity provided by Prussian-blue (PB)-modified electrodes
towards H2O2 detection, such electrochemical sensors have been denominated as ‘artificial peroxidase’ PD-1 inhibitor (Karyakin and Karyakina, 1999, Lu et al., 2006 and Munoz et al., 2007). Nevertheless, the Nafion coating was necessary in order to eliminate interferences from the sample matrix which can affect the electrode response and consequently disturbs the method accuracy (Ping et al., 2010). High-performance analytical methods are mandatory in routine laboratories of food analysis. Batch injection analysis (BIA) is a promising technique to attend such demands due to its improvements in versatility, reproducibility, analytical frequency, portability and sample size. Its combination with electrochemical detectors provides additional advantages of electrochemical sensors such as selectivity, sensitivity and fast response to the development of analytical methods (Quintino &
Angnes, 2004). An electronic micropipette injects precise sample plugs (at a programmable speed) directly onto the working electrode surface, which is immersed in a large-volume
blank PtdIns(3,4)P2 solution, and a fast electrochemical response proportional to the analyte concentration is registered. In this work, we report a novel application selleck chemical of BIA with amperometric detection for the highly rapid, selective and sensitive method for the determination of H2O2 in high and low-fat milk samples. A PB-modified graphite-composite electrode provided fast and reproducible amperometric responses to H2O2 in 10-fold diluted samples. Solutions were prepared with deionized water (Direct-Q3, Millipore, Bedford, MA, USA) with a resistivity no less than 18.2 MΩ-cm. Araldite® epoxy adhesive from Brascola (Joinville, Brazil), cyclohexanone and hydrogen peroxide from Vetec (Rio de Janeiro, Brazil), graphite (Ø: 1–2 μm) from Sigma–Aldrich (Milwaukee, WI, USA), iron(III) chloride, potassium monohydrogen phosphate, potassium dihydrogen-phosphate, and potassium ferricyanide from Proquímios (Rio de Janeiro, Brazil) were of analytical grade and used without any further purification. Phosphate buffer solution (pH = 7.2, 0.05 mol L−1 K2HPO4/KH2PO4) containing 0.1 mol L−1 KCl was used as supporting electrolyte. Stock solutions of hydrogen peroxide were freshly prepared just before experiments. All electrochemical measurements were performed using a μ-Autolab Type III (Eco Chemie, Utrecht, Netherlands) controlled by GPES4.9.007 software (General Purpose Electrochemical System).