Determination of Inorganic Arsenic Speciation in Municipal Solid Waste Incineration Fly Ash by High Performance Liquid Chromatography-Hydride Generation-Atomic Fluorescence Spectroscopy with Phosphoric Acid as Extracting Agent

Abstract

A method for the determination of arsenic speciation in municipal solid waste incineration fly ash was developed by high performance liquid chromatography (HPLC) coupled with hydride generation atomic fluorescence spectroscopy (HG-AFS). Before determination, various forms of arsenic were extracted with phosphoric acid through microwave digestion. The effect of phosphoric acid in the extracted solution on the speciation analysis of inorganic arsenic (As(III)/As(V)) was studied in detail. The results showed that when using diammonium phosphate as the mobile phase, the determination of As(V) was adversely affected. The increasing flow rate of mobile phase hardly reduced the adverse influence caused by phosphoric acid. The adverse influence was effectively suppressed when a mixed solution of disodium hydrogen phosphate/potassium dihydrogen phosphate (pH = 6.864) was used as the mobile phase. By using the improved method, As(III) and As(V) could be separated in 5 min, and the detection limits of As(III) and As(V) were 0.063 μg L−1 and 0.110 μg L−1, respectively. The recovery rate of As(III) and As(V) in spiked standard sample was satisfactory (86.9%–102.6%). The determination of arsenic species in fly ashes sampled from four different municipal solid waste incineration plants were successfully accomplished by using the method. The results showed that the arsenic was predominantly in the form of As(V).