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periodic chart have very rich emission spectra that can cause spectral overlap," Houk explained, "but the mass spectral isotopic patterns for those elements are much less complicated." Detection limits in ICP/MS are, in general, better than in plasma emission spectrometry. And the ICP/MS makes it possible to determine elemental isotopes and to use isotope dilution for quantitation. Will other vendors jump on the ICP/MS bandwagon? The answer is
almost certainly yes. "I have seen interest from both mass spectrometer manufacturers and emission spectrometer manufacturers," says Houk. "VG Instruments and Sciex are both mass spectrometer manufacturers, but the people who make emission spectrometers are sitting up and taking notice too. Whether they'll try building quadrupoles and vacuum systems is another matter, but they're keeping an eye on what's going on."
Follow-Up on the Ian Trap Detector While we're on the subject of new instruments discussed in last year's Pittsburgh Conference FOCUS coverage, remember the ion trap detector (ITD)? Manufactured by Finnigan MAT, the ITD (June 1983, pp. 72628 A) is a combined ion source and mass analysis device that uses radiofrequency fields to store ions. When hooked up to a gas chromatograph, the ITD provides a very inexpensive alternative to conventional gas chromatography-mass spectrometry. The ITD is still around, but, as it happens, not a single unit has been shipped. Late last year the company informed all those who had ordered ITDs that there were technical difficulties and that the shipping schedule had been suspended. "The physics involved turned out to
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be more difficult to understand than we anticipated one year ago," said Finnigan chairman and president T. Z. Chu. "We resolved the problem by going back to a very fundamental restudy of the phenomenon, and we reached a correct understanding of what's going on inside the trap. Once we understood that, the solution became very straightforward." According to Chu, "All throughout this time we received exactly two cancellations out of 100 orders, both because the funding ran out. I think that's some indication that people really want us to be successful with this product. We continue to be very optimistic about the size of the market for the ITD." Chu said that Finnigan would finally be shipping ITDs before the end of this year.
