New two-step extraction method in antimony speciation using HPLC-ICP-MS technique in inhalable particulate matter (PM2.5)

The present paper proposed an analytical method for speciation analysis of inorganic antimony in inhalable particulate matter, PM2.5, using high performance liquid chromatography coupling with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). A new extraction method consisted of reducing extraction and oxidizing extraction using EDTA as the key component in the extractant has obtained better extraction yield and preserves stability of both species during the extraction process. Stability of Sb species in EDTA-saturated nitric or tartric acid solution and in aqueous solution were carefully investigated. Using the optimized conditions, the method allows for the determination of Sb(III) and Sb(V) in PM2.5 samples with limits of 0.10 and 0.06 ng m(-3), respectively. The precision, expressed as relative standard deviation (RSD), was always lower than 8.5% and 6.6% for Sb(III) and Sb(V), respectively. The spiked recovery rates of Sb species at three different concentration levels were in the range of 90.0-110.0%. The extraction yield of the sequential extraction process confirmed by analysis of a certified reference material of urban particulate matter, NIST1648a, furnished by National Institute of Standards and Technology was 60%. This method was applied to determine Sb(III) and Sb(V) in PM2.5 samples collected in urban area in Ningbo City, China. The results showed that both Sb(V) and Sb(III) were found in most of the samples analyzed, Sb(V) being the main one, which represents 69-87% of the total Sb extracted in the considered samples, whereas Sb(III) represents the remaining 13-31%.