ABSTRACT

The fundamental principle of ICP-MS is based on interfacing a plasma discharge at 10,000 K to a mass spectrometer at approximately 10−6 Torr. The sample is introduced in the form of a liquid aerosol (or solid particles with laser sampling) and then ionized in the plasma where the matrix and analyte ions are directed into the mass analyzer where they are separated and finally measured by the ion detection system. This principle, which gives ICP-MS its unequalled isotopic selectivity and sensitivity, unfortunately contributes to some of its weaknesses-the fact that the sample “flows into” the spectrometer and not “passed it” as with flame AA and ICP-OES. This means that the potential for thermal problems, corrosion, chemical attack, blockage, matrix deposits, and drift is much higher than with the other AS techniques. However, being fully aware of this fact and carrying out regular inspection of instrumental components can reduce and sometimes eliminate many of these potential problem areas. There is no question that a laboratory that initiates a routine preventative maintenance plan stands a much better chance of having an instrument that is ready and available for analysis whenever it is needed, compared to a laboratory that basically ignores these issues and assumes the instrument will look after itself.