inorganic arsenic speciation in natural waters

A method was developed for inorganic arsenic speciation analysis of water samples by a microsample injection system coupled with inductively coupled plasma mass spectrometry (MIS-ICP-MS) following a validated dispersive liquid-liquid microextraction (DLLME). Prior to DLLME speciation analysis, a simple robust microsample injection system was successfully adapted to ICP-MS. A sampling volume of 90 mu L provided almost the same signals as the signals obtained by means of a conventional continuous nebulization sampling system for the ICP-MS instrument. After DLLME, the final solution was injected into nebulizer of ICP-MS using the microsample injection system. Under the optimized conditions, the analyte from only 5.0mL water sample was concentrated by a factor of 48 with detection limits reaching 0.0031 mu gL(-1) for arsenic. The calibration curve had a linear range of 0.0084-0.0800 mu gL(-1) (r(2)=0.999). The relative standard deviations (RSD, n=6) were