Alkaline Phosphatase Inhibition-Based Amperometric Biosensor for the Detection of Carbofuran

An indirect amperometric biosensor was designed for the detection of carbofuran exploiting inhibition of the enzymatic activity of alkaline phosphatase immobilized on a carbon nano-powder paste electrode (CNPPE). Measurements were performed by chronoamperometrical monitoring on the inhibition of the enzyme activity. Experimental parameters were investigated and optimized. The biosensor showed optimum performance at an operation potential at +0.75 V vs Ag/AgCl at pH 8.5 (stirred phosphate buffer solution, 0.1 mol/L). The calibration curve had a dynamic range of 10 - 97 mu g/L carbofuran with a detection limit at 10 mu g/L. The repeatability was 2.3 % (3 measurements, 50 mu g/L), the reproducibility was 3.4 % (3 sensors). The determination of carbofuran in spiked water and chili samples using the proposed biosensor was satisfactory when compared to a spectrophotometric reference method. The results showed no significant difference at 95 % confidence level with t-test statistics.