Convenient Measurements and Speciation of Arsenic in Water by Use of Simple Pretreatments for Atomic Absorption Spectrometry in Combination with Hydride Generation

Abstract

A combination of three different simple pretreatments is useful and convenient for speciation of As by atomic absorption spectrometry in combination with hydride generation. One of the three pretreatments involves no pre-reduction of As(V) to (III) (PT1). The next one involves pre-reduction by KI (PT2), and the last one involves mineralization of organic As by K₂S₂O₈ and NaOH (PT3) followed by PT2. Micro-wave radiation is effective in PT2 and PT3. The proposed method takes advantage of incomplete but reproducible recovery of As(V) with PT1. The recovery coefficient of As(V) in PT1, κ, is introduced. The value of κ is kept constant during each experimental run under a condition of constant NaBH₄ concentration. The actual amount of each form of As is obtained by solving simultaneous equations which are derived from As amounts detectable after each of the three pretreatments. Analytical results of speciation of As for model sample solutions, containing up to 40 ppb total As, are satisfactory.