CONFIDENCE ELLIPSES FOR THE QUANTITATIVE ANALYSIS FROM THE WHOLE NMR SPECTRUM.
| Authors | |
|---|---|
| Year of publication | 2001 |
| Type | Article in Proceedings |
| Conference | 16th NMR Valtice, 23.-25.4.2001 |
| MU Faculty or unit | |
| Citation | |
| Field | Physical chemistry and theoretical chemistry |
| Keywords | low resolution; quantitative analysis; confidence ellipse |
| Description | If the NMR spectrum does not contain any signal suitable for integration, a quantivative determination can be made from the whole spectrum which was properly broadened by an exponential multiplication of the FID. Then the mathematical procedure comprises either a multivariate calibration or a nonparametric estimation. For both methods an accuracy of the results is not easy to find out. However, it can be estimated from a confidence ellipse. For this graphical presentation a calibration set of, e.g., seven NMR spectra from repeated measurement of the same sample with the concentration of analyte corresponding to that which will be determined is obtained and each spectral curve is transformed into two coefficients x and y. These are in fact real and imaginary parts of the first complex number after the Fourier transform of the NMR spectrum.Around these points the confidence ellipses are drawn and then the point from sample with different concentration is added. If the point is pretty out of the ellipses, the corresponding concentration will be easy to determine. A point near to the ellipse shows probable limit of the quantitative determination. |
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