Emulsion liquid membrane separation of As(III) and As(V) with subsequent determination by electrothermal AAS

Liquid membranes consisting of L113A (surfactant), liquid paraffin (stabili zer), and kerosene (solvent) were used to separate arsenic(III) and arsenic (V) with HCl solution as the external phase and NaOH solution as the intern al phase, followed by their determination with electrothermal atomic absorp tion spectrometry (ETAAS) using Ni salt as the matrix modifier. The effects on the recovery of arsenic were studied and the optimum conditions of sepa ration and determination established. Total arsenic was determined after As (V) was reduced to As(III) by addition of sufficient KI and As(V) was deter mined by subtracting the value of As(III) from total arsenic. The RSD of As (III) and As(V)) was less than 4% and the limit of detection up to several mug L-1. The interference of most foreign ions was avoided. The method was applied to aqueous samples with satisfactory recoveries of more than 93.8%.