31 January 1994 Optimization of quantitative infrared analysis
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Proceedings Volume 2089, 9th International Conference on Fourier Transform Spectroscopy; (1994) https://doi.org/10.1117/12.166724
Event: Fourier Transform Spectroscopy: Ninth International Conference, 1993, Calgary, Canada
A number of industrial processes, especially quality assurance procedures, accept information on relative quantities of components in mixtures, whenever absolute values for the quantitative analysis are unavailable. These relative quantities may be determined from infrared intensity ratios even though known standards are unavailable. Repeatability [vs precisionhl in quantitative analysis is a critical parameter for meaningful results. In any given analysis, multiple runs provide "answers" with a certain standard deviation. Obviously, the lower the standard deviation, the better the precision. In attempting to minimize the standard deviation and thus improve precision, we need to delineate which contributing factors we have control over (such as sample preparation techniques, data analysis methodology) and which factors we have little control over (environmental and instrument noise, for example). For a given set of conditions, the best instrumental precision achievable on an IR instrument should be determinable. Traditionally, the term "signal-to-noise" (S/N) has been used for a single spectrum, realizing that S/N improves with an increase in number of scans coadded for generation of that single spectrum. However, the S/N ratio does not directly reflect the precision achievable for an absorbing band. We prefer to use the phrase "maximum achievable instrument precision" (MAIP), which is equivalent to the minimum relative standard deviation for a given peak (either height or area) in spectra. For a specific analysis, the analyst should have in mind the desired precision. Only if the desired precision is less than the MA1P will the analysis be feasible. Once the MAIP is established, other experimental procedures may be modified to improve the analytical precision, if it is below that which is expected (the MAIP).
© (1994) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Richard W. Duerst, Richard W. Duerst, W. E. Breneman, W. E. Breneman, Rebecca M. Dittmar, Rebecca M. Dittmar, Richard E. Drugge, Richard E. Drugge, Jim E. Gagnon, Jim E. Gagnon, Robert A. Pranis, Robert A. Pranis, Colleen K. Spicer, Colleen K. Spicer, William L. Stebbings, William L. Stebbings, J. W. Westberg, J. W. Westberg, Marilyn D. Duerst, Marilyn D. Duerst, } "Optimization of quantitative infrared analysis", Proc. SPIE 2089, 9th International Conference on Fourier Transform Spectroscopy, (31 January 1994); doi: 10.1117/12.166724; https://doi.org/10.1117/12.166724

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