WE'VE GOT ION CHROMATOGRAPHY DOWN TO A E ^ \ m m COLUMN
sor, which performs a full double-pre cision (32 bits per word), 2K complex F F T in considerably less than 1 s. In fact, on data systems incorporating this device, at intervals of 0.75 s a complete 8-cm - 1 resolution spectrum can be calculated at the same time as the next interferogram scan set is being acquired and the spectrum from the previous scan set (or the recon structed chromatogram) is being dis played. This integration of hardware, firmware, and software represented a major advance in capillary GC/FT-IR data processing, and even by the 1983 Pittsburgh Conference its perfor mance still had not been equaled by any commercial data system in this very competitive market. The saving of memory when spectra rather than interferograms can be stored may be quite remarkable. First of all, since the dynamic range of spec tra is less than that of interferograms,
it is only necessary to store spectra in single precision. Also only one point per resolution element need be stored. Therefore for spectra measured at 8-cm _1 resolution, only 450 points are required to represent the entire mid-IR spectrum. If one makes the as sumption that certain regions are like ly to contain very little useful chemi cal information (e.g., between 2800 and 1900 c m - 1 because of the lack of many characteristic group frequencies in this region, and below 600 c m - 1 be cause of the response characteristics of the medium-range MCT detector), only 312 points need be stored. Spectral Searching
After GC/FT-IR spectra have all been calculated, the task of identi fying each eluate remains. At the present state of the art, a great many peaks in capillary chromatograms will yield IR spectra with a sufficiently
Table I. IR and Mass Spectral Search Results for Minor Peaks in G-S and TIC Chromatograms IR spectral search HII
A c t u a l Size
Bio-Rad has new resin based, 50 mm ion exchange columns for Ion Chromatography. They give the same separation as conven tional long columns, with less chance for band spreading. •
Porous polymer anion and cation ex changers- pH 0-14.
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10 μπι particles - high resolution, less than 10 minutes analysis.
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Pressure
