Page 154 - Inorganic Mass Spectrometry - Fundamentals and Applications

144 Olesik

~ systems still require further improvement in terms of
e
~
~
~ a ~nt~Qd~ct~Q~
efficiency, noise, solvent removal, and ease of use. Analysis of small volumes is
becoming more comon with micron~bulizers and efficient desolvation systems.
However, these systems are often more diffkult to use than conventional
nebulizer/spray chamber systems. Nebulizer clogging and fouling of membrane
desolvators by aerosol remain problems. Smple in~oduction systems that may
provide nearly 100% analyte transport efficiency at sample uptake rates of more
than 0.5 nL/min may be within reach. As the mount of sample entering the
plasma increases, chemical matrix effects tend to become more severe. Calibra-
tion for laser ablation sampling is still a problem because of sam~1e”dependent
changes in the amount of material ablated and elemental fractionation, although
progress has been made. Electrothermal vaporization still requires the art of
modifiers; again progress is being made.
~nst~~~e~t ~uinte~a~ce costs are high. Prices range from about
and
~180,000 (U.S. dollars, 1998) for quadrupole ins~ments to almost ~1,000,000
(U.S. dollars, 1998) for a fully capable multicollector sector-based ins~ment
and laser ablation sampling. About 10 to 20 L/min of Ar is used by the ICP.
Sam~ling and skimmer cones cost $800 to $3000 (U.S. dollars, 1998), depending
on material. Detector lifetime may be less than 1 year. Vacuum pumps have
limited lifetimes. Of course, the rapid multielement analysis capabilities, low
detection limits, and isotope measurements often provide information that makes
ICP-MS successful financially as well as scientifically.
~ntelzigent inst~~~e~ts could broaden the use of ICP-MS while enhancing
analysis reliability. The effect of spectral overlaps, chemical matrix effects, and
drift due to sample deposition or orifice clogging may not be obvious to the
operator unless knowledge of the sample chemistry is sufficient or procedures are
specifically designed to check for these potential problems. Because the instru-
ments can rapidly scan the entire mass spectrum, information on components in
the sample at high concen~ation, changes in background ion signals, and isotope
ratios might be used as part of a diagnostic system built into the instrument.

mass
1. Jarvis, K. E.; Gray, A. L.; Houk, R, S. hand boo^ o~in~uctively coupledplas~a
spectro~et~;
Blackie; Chapman and Hall: Glasgow; New York, 1992.
2. Montaser, A. ~n~~ctively Coupled Pl~s~a Mass S~ectromet~; Wiley-VCH: New
York, 1997.
3. Reed, N. M.; Carins, R. 0.; Hutton, R. C. J. Anal. Atom. Spectro~.
4. S, A.; Wa~er, J.; Browner, R. E; He~an~is, Spectroc
V.
, 43B, 1321-1335.
5. Olesik, J. W.; Bates, L. C. Spectroc~imic~ Acta 19