Voltammetric Approach of Arsenic (Total) Determination in Blood using Sctrace Gold Electrode

Abstract

Normal levels of Arsenic (As) in the blood of unexposed individuals arereported to be less than 1 μg/L. The quantitative determination of arsenic traces and its compounds is significant to assess its deleterious effects on human health. The use of conventional methods (AAS and ICP–MS) for trace metal detection extend several issues such as high cost of equipment, need of highly trained engineers and extensive sample preparations. An alternativevoltammetric method has been developed for arsenic determination in blood using scTrace Gold elcetrode. The scTrace Gold sensor holds all three electrodes together required for a voltammetric determination. The working electrode is a gold microwire whereas reference and auxiliary electrodes are screen printed electrodes. Human blood was processed by closed microwave digestion using nitric acid and hydrogen peroxide. Arsenic determination was carried out by standard addition method using primary solution being swept at a rate of 0.992 V/s and pulse amplitude of 0.020 V. Cleaning was done at – 1.0V for 60 seconds and potential was scanned from 0.4V to -1.0V on RDE/SSE at 2400 rpm speed. With this method, the total arsenic i.e., As(III) + As(V) in the sample can be determined. As(V) species being electrochemically inactive are reduced in-situ by nascent hydrogen to As (III). Along with the As(III) present in the sample, it is further reduced electrochemically to As(0) and deposited on the gold working electrode in the same step. During the subsequent stripping step the deposited As(0) is reoxidized to As(III) giving the analytical signal. Arsenic was deposited on the electrode at -0.250 V for 5 seconds. The deposited metal was swept by scanning the potential from -0.300V to 0.40 V using square wave mode. The stripping current was correlated with the concentration of the metal present in the sample. The detection limit of arsenic was found to be 0.9 μg/L and the calibration was linear up to a concentration of 20 μg/L.