ISSN:
0030-493X
Keywords:
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
A system is described in which a medium-sized double-focusing mass spectrometer is coupled on-line to a small (4K memory words) computer. The system can produce complete elemental composition data within two minutes after the completion of the mass spectral scan.The inherent speed of the processor and memory sub-systems is effectively retained through the utilization of a low-cost random-access bulk-storage device and other high-speed peripherals.An attempt is made to define both the theoretical and practical considerations necessary in utilizing a small digital computer as an integral part of a chemical experiment, specifically as applied to high-resolution mass spectrometry. Important aspects include the interaction of resolution and errors of mass measurement, the contribution of noise to observed errors, the effect of peak shape on such errors, the techniques of analog and digital signal processing, the criteria of efficient system design and the fundamental validity of applying a mathematical model, such as the centroid, to a basically statistical situation.The centroid method of calculating peak centers is shown to be fundamentally correct and the resultant error due to statistics diminishes in absolute value as the peak width decreases, that is, as the resolution increases, errors being approximately one-half as large at R = 10,000 as those at R = 2200. The overall mass measuring accuracy has been investigated at resolutions up to R = 10,000 using several different organic compounds and has been shown to be about 12 ppm for a single scan. Multiple scan averaging reduces this error by approximately the square root of the numbers of scans.
Additional Material:
11 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/oms.1210040104
Permalink
