Speciation of mercury using capillary electrophoresis coupled to volatile species generation-inductively coupled plasma mass spectrometry

The development and analytical characterisation of an on-line coupled capil lary electrophoresis (CE)-volatile species generation (VSG)-inductively cou pled plasma mass spectrometry (ICP-MS) system for the separation and determ ination of different species of mercury is described. The mercury species s tudied (inorganic mercury, methylmercury and ethylmercury) are separated as mercury-cysteine complexes by capillary zone electrophoresis (CE) in a 100 cm x 75 mum id fused silica capillary at 25 kV and using a 20 mM sodium te traborate decahydrate buffer (pH = 9.3). The detection is carried Out on-li ne by both quadrupole (Q) and double focusing (DF) ICP-MS using a VSG syste m with NaBH4 reduction as the sample introduction device. The CE-VSG-ICP-MS interface construction provides an electrical connection for stable electr ophoretic separations and allows on-line volatile species formation, these being separated from the liquid in a gas-liquid separator, allowing for fin al transport of the volatile analyte derivatives into the plasma. Character isation and optimization of operation parameters of this interface are disc ussed. The analytical performance characteristics of the developed CE-VSG-I CP-MS methodology were evaluated and detection limits in the low mug l(-1) range were achieved. The accuracy of the method has also been checked by an alysing a certified biological reference material (DOLT-2) with satisfactor y results.