Stripping Voltammetric Determination of Mercury in Fish Oil Capsules Using a Screen-printed Gold Electrode

This work presents a simple electrochemical method for Hg determination in fish oil capsules using anodic stripping voltammetry (ASV) on a screen-printed gold electrode (SPGE). Samples were treated in an ultrasonic bath for 15min in the presence of a 1:1 (v/v) concentrated HCl/H2O2 mixture at room temperature. The limit of detection (LOD) was estimated as 0.25gL(-1) (corresponding to 7.6gkg(-1) of oil) with a linear range between 5 and 400gL(-1) (90s of deposition time). The analyzed fish oil samples presented Hg concentration below the LOD value. Recovery values for samples spiked with oil standard containing Hg ranged from 95 to 105%. The method is precise (inter-day and intra-day RSD<4% for n=3) as well as the SPGE sensors (RSD=4.3%, n=3), which were used continuously (around 100 analyses without replacement) under such oxidation media. The proposed method is feasible to be applied for on-site determinations due to the portability of sensing and sample treatment approaches.