Michael Leist Varian
Analytical Instruments Mulgrave, Victoria 3170, Australia E-mail: firstname.lastname@example.org
As toxicity, mobility, and bioavailability can differ greatly between the various chemical species in which an element occurs, reporting only the total concentrations can often be misleading. Arsenic is one such example where the various species differ; the inorganic trivalent form (As III) is the most toxic, followed by the inorganic pentavalent form (As V). Other common forms of arsenic include monomethyl arsenic (MMA), dimethyl arsenic (DMA) and arsenobetaine (AsB), which have signifi cantly reduced toxicities. Therefore, separation and detection of these species can greatly assist risk-based toxicity assessments.
When Liquid Chromatography (LC) is interfaced with Inductively Coupled Plasma Mass Spectrometry (ICP-MS), species elute one by one from the LC column directly to the ICP-MS for detection by elemental speciation. The coupling of LC to ICP-MS is a straight forward task; the LC column is connected to the nebulizer of the ICP-MS by a piece of PEEK tubing, and no hardware changes are required to either the LC or the ICP-MS. Coupling an LC to a Varian ICP-MS has the added advantage of offering high sensitivity, with over 80% of the analyte ions passing through the skimmer cone being transferred to the quadrupole1. The Varian ICP-MS, with its patented 90 degree ion mirror2, is the worlds fi rst ICP-MS with tunable gigahertz sensitivity.
The following experiment shows the sensitivity and detection capabilities of the high sensitivity Varian ICP-MS for element speciation.
A schematic of the overall system is shown in Figure 1.
The LC system used was a Varian ProStar 230 Tertiary Solvent Delivery Module,