Voltammetric technique for determination of arsenic residues in calcium carbide ripened climacteric fruits

Calcium carbide (CaC2) often being used as one of the fruit ripening agents due to cheaper cost and readily available in the market. However, it is not recommended to use CaC2 in Malaysia, because the arsenic (As) residues which present as impurities in this fruit ripening agents can cause serious adverse effect to human consumption. Voltammetric measurement using a gold electrode in acidic medium (2 M HCl) was developed to determine the As residues in the fruit samples. This technique observed the electrochemical behaviour and quantitative analysis of the As(V) species at the gold electrode. It was found that As(V) undergone irreversible oxidation process at the gold electrode. The working parameters validated for differential pulse anodic stripping voltammetry (DPASV) were Ei =-0.20 V, Ef = +0.30 V, v = 0.02 V/s, Eacc1 =-1.10 V, tacc1 = 120 s, Eacc2 = +0.04V, tacc2 = 10 s and pulse amplitude = 0.05 V which produced peak potential at +0.10 V. The LOD and LOQ using statistical method were 1.3 ppb and 4 ppb, respectively. While by visual observation were 0.7 ppb and 2 ppb, respectively. The method successfully applied for the estimation of As residue in fruit ripening that was used CaC2 as a ripening agent and also As(V) in fruits bought from local market. Therefore, the developed voltammetry method can be a great potential instrument to measure As(V) in fruit sample