A novel approach of flow system with a 3D-printed Direct Injector Detector for electrochemical determination of cadmium and lead

Abstract

A simple approach based on a flow system equipped with a novel 3D-printed Direct Injection Detector (DID), first time working in an electrochemical mode, is proposed to simultaneously determine cadmium and lead cations in water and food samples. The use of flow DID combined with electrochemical detection for the first time allowed to significantly reduce the volume of dosed reagents and waste generation and increase the automation of the determination, which perfectly fits into the principles of “Green Analytical Chemistry”. For voltammetric detection, the screen-printed carbon electrodes (SPCEs) modified with carbonized halloysite (C_Hal) and multi-walled carbon nanotubes (MWCNTs) were used (MWCNTs/C_Hal/Nafion/SPCE). The tested sensor exhibited linear response in concentration ranges: 15 – 3000 nmol L–1. The limits of detection were estimated as LODCd = 4.30 nmol L–1 (0.48 ng mL−1) and LODPb = 0.97 nmol L–1 (0.20 ng mL−1). Thus, the use of DID, as well as the Signal Increment Standard Addition Method, allowed to determine the cadmium and lead in tap, well, mineral waters and also in honey and rice samples with a recovery in the range of 95–103% and with a precision error of less than 7%.