ABSTRACT
Longer retention time resulting in a slow separation is the major drawback of existing methodologies based on inductively coupled plasma mass spectrometry (ICP-MS) coupled to high performance liquid chromatography (HPLC-ICP-MS) and ion chromatography (IC-ICP-MS) for speciation of arsenic (As). This study developed a fast analytical protocol based on Ultra-High Performance Liquid Chromatography (UHPLC) hyphenated to ICP-MS detection for simultaneous separation and quantification of arsenite (As(III)), arsenate (As(V)), dimethylarsonate (DMA(V)) and monomethylarsenate (MMA(V)). A mixed mobile phase containing 8.5 mM of NH4H2PO4 and NH4NO3 (1:1) at pH 6.0 achieved the separation of As species within 5 min which is almost a double saving in analysis time per sample compared to the existing methods (9-15 min). Unlike HPLC, UHPLC did not generate a higher column back pressure with increasing flow rate up to 2.5 mL/min resulting in a faster separation with excellent resolution of peaks. Limits of detection for As species were in the range of 0.3-0.5 µg/L. Faster separation achieved from the proposed method is indeed analytically cost effective in terms of ICP-MS running cost and energy consumption.
