ICP-Atomic Emission Spectrometer and Ion Chromatograph

Varian Vista Pro Axial ICP-AES (Inductively-Coupled Plasma Atomic Emission Spectrometer)

This apparatus analyses particle-free liquid samples for multiple elements simultaneously. Samples are typically natural water samples, extracts from soils, or digests from soils, rocks, or organics such as plant detritus. In general, they should be presented in 2% nitric acid matrix to retain analytes in solution and match the calibration standards. About 3 - 5 mL is consumed per typical analysis. One to many elements may be analysed simultaneously, and many spectral lines may be analysed for a given element, so as to best avoid interference, saturation effects etc. Detection limits are best (single parts per billion) for alkaline earths such as Sr, Ba, and 3d transition metals. Worse limits are obtained for p-block metals and metalloids such as As, Sn, Pb (hundreds of ppb) and electronegative elements such as Au, S (ppm). Very electronegative elements, rare gases, and Rb, Cs cannot be analysed. Dilute samples (<0.05% total dissolved solids) are preferred, but we have slower, more expensive methods available that will cope with salinities similar to sea water.

ICP-AES gives no information on speciation of an element, due to the high temperature of the plasma, which decomposes molecules.

Dionex Ion Chromatograph

This apparatus is fitted with an anion chromatography column which analyses water samples for fluoride, chloride, bromide+iodide, nitrate, sulfate and phosphate. Hence, it is complementary to the ICP-AES. The anions are separated in the column, and then detected downstream as pulses in electrical conductivity. Water samples must be close to neutral, NOT acidified.