A simple electrochemical hydride generation apparatus for the determination of inorganic arsenic in food samples with an atomic fluorescence spectrometer

摘要

A simple electrochemical hydride generation (EcHG) apparatus was developed for arsenic determination by atomic fluorescence spectrometry. The apparatus consists of two graphite tubes (as the atomizer in graphite furnace atomic-absorption spectrometry) that were used as cathode and anode cells and are connected together in series by an insulated plastic pipe, an AC to DC power wall plug adapter (12 V 2 A) used with portable computers, and a gas-liquid separator. The apparatus did not include an ion-exchange membrane, and an analyte solution containing thiourea and hydrochloric acid was used for both electrolytes without a specific anode only solution. The experimental results showed that EcHG efficiencies and detection limits depended on the output voltage and the concentration of HCl and thiourea used. Under the optimized conditions (solution flow rate of 3 ml mim(-1), carrier argon gas flow rate of 400 ml min(-1), a 12 V 2 A DC power adapter, and concentrations of thiourea and HCl of 1%(m/v) and 10%(v/v), respectively), the limit of detection of arsenic was 0.3 ng ml(-1) (3 sigma), and the relative standard deviation was 4% for ten consecutive measurements of a 40 ng ml(-1) As(III) standard solution. The calibration curve was linear up to 100 ng ml(-1). The accuracy of the method was verified by the determination of arsenic in two certified reference materials (GBW10045 for rice flour and GBW10015 for spinach), and the results were in good agreement with the certified values.