Inductively Coupled Plasma Instruments

Quadrupole ICP-MS

The ARF has two of these instruments (Thermo Scientific, X Series 2), which are used for research, consultancy and teaching. The rapid scanning ability of a quadrupole analyser allows the ion signal of an individual element to be quantified in a couple of seconds, giving fast multi-element analysis for a wide range of sample types.

Detection limits can be as low as the part per trillion range (nanogram per litre), roughly the equivalent of adding a teaspoon of salt to an Olympic-sized swimming pool, although in practice once sample digestion dilutions are taken into account, low part per billion (microgram per litre) levels are achieved. If preconcentration procedures are applied, then limits of detection can be lowered significantly. The linear range can span 5 orders of magnitude.

ICP-OES

We operate a Varian 725-ES ICP-OES instrument. This is a type of emission spectroscopy that uses a plasma to produce excited atoms that emit electromagnetic radiation at a wavelength characteristic of a particular element. The intensity of this emission is indicative of the concentration of the element within the sample. Our ICP-AES instrument uses a charge coupled device in the detection system and allows the rapid, simultaneous detection of most elements contained within a sample. Detection limits for this instrument typically lie in the low part per billion region, although as with ICP-MS, these are approximately two orders of magnitude higher once digestion dilutions are taken into account. The linear range can span 4 or 5 orders of magnitude.

Between them, the ICP-MS instruments (that have a linear range covering 0.01 – 1000 µg/L) and the ICP-OES instrument (that has a linear range covering typically 0.01 – 2000 mg/L), can cover trace elemental measurements in concentration ranges spanning 8 or 9 orders of magnitude.

A wide variety of sample introduction systems, including conventional nebulisation, nebulisation coupled with High Performance Liquid Chromatography (HPLC) or flow injection analysis and hydride / cold vapour generation can be applied for sample introduction to our ICP-MS or ICP-AES instruments, either for elemental speciation work and/or to enhance instrumental sensitivity.