Electrochemical determination of lead in water samples using modified electrode based on polyazulene derivates

Abstract

The purpose of the study was to develop an electrochemical method for detection of lead at low level of contamination in water samples using a carbon glassy electrode modified with the functionalized azulene: (2E)-2-(azulen-1-ylmethylidene) hydrazine carbothioamide (L) as a complexing polymer film. The modified electrodes were prepared in L solutions (1mM) in acetonitrile (CH3CN) containing tetra n-butyl ammonium perchlorate (0.1 M TBAP) as supporting electrolyte. The analyses were performed on Autolab PGSTAT 12 Potentiostat, all the reagents used were ultratrace quality. The electrochemical method include four steps: 1) polymeric film formation by controlled potential electrolysis (CPE) at 1.7V using a charge of 1 mC under argon atmosphere; 2) film conditioning in 0.1 M buffer acetate solution using cyclic voltammetry; 3) complexation in a standard solution prepared from lead nitrate (II) using ultrapure water as matrix or a real sample; 4) stripping differential pulse voltammetry method (DPV) in acetate buffer at 5.5 pH, after 180 seconds reduction time at a reduction potential of -1.2 V. The determination time for a standard solution or real sample is around 45 minutes. The calibration curve was plotted in the range 1 to 50 µg/L Pb (II). The precision experiments were performed at 10 µg/L Pb (II). The precision for polymeric film formation on the glassy carbon electrode was 13.5%, while the intermediate precision test indicated a value of 15.5%. Evaluation of the method performant parameters confirm that the proposed method is suitable to detect and quantify lead content in water samples.