Column preconcentration of mercury as HgI 42− using methyltrioctylammonium chloride-naphthalene adsorbent with subsequent anodic stripping-differential pulse voltammetric determination

Abstract

A sensitive and selective preconcentration method has been developed for mercury using naphthalene-methyltrioctylammonium chloride (Aliquat 336s) as an adsorbent. Mercury as HgI 4 2− was retained by the adsorbent in the column at a flow rate of 1 ml min −1. The column was washed by a solution of sodium tetraphenylborate and sodium iodide to elute the adsorbed mercury. The eluents were collected in a 10 ml volumetric flask and diluted to the mark with water, transferred to a voltammetric cell and anodic stripping-differential pulse voltammetry was performed. Preconcentration factors of 40 and 80 could be achieved when using a 10 and 5 ml voltammetric cell, respectively. The calibration graph was linear in the range of 1.2–8.7 ng ml −1 Hg(II) in the initial solution with r=0.9998 ( n=6) and the 3 s detection limit was 0.13 ng ml −1 when using a 10 ml cell. The relative standard deviation for eight replicate measurements of 1.2, 5.0 and 8.7 ng ml −1 of Hg(II) in the initial solution was 0.51, 0.71 and 0.80%, respectively. The proposed method was successfully applied to determination of mercury in natural waters, wastewater and synthetic samples.