Detection and interference analysis of lead in acid-containing fruits using gel/graphite paper electrode based on extraction-electrochemical detection

Electrochemical detection is an applicable rapid detection technology, but it is always limited by sample treatment and matrix interference. In this study, two gel/graphite paper electrodes were obtained by drop coating of sodium alginate gel and chitosan gel onto 0.1 mm graphite paper. Comparations of anti-interference performance and stability indicated that sodium alginate gel/graphite paper electrode (GGPBE) was the preferred term for establishing a rapid determination method for Pb in fruits. Based on the contents of organic acids and main metal ions in fruits, analysis and control of matrix interference were conducted. Organic acids, such as ascorbic acid, citric acid and quinic acid, caused greater interferences than metal ions. Mg(II) and Fe(III) were the notable factors of co-interference with organic acids. Matrix interference could be controlled in 3.92% by chemical oxidation using H 2 O 2 combined with HNO 3 ultrasonic extraction. The established linear range of Pb(II) was 0.1 ∽ 21.0 µg/L and LOD was 0.0274 µg/L under square wave anodic stripping voltammetry method. In the detection of 9 fruits, the contents of Pb were below 0.1 mg/kg. This work developed an easily prepared gel/graphite paper electrode and provided a rapid sample treating-detection method of lead in fruits.