Introduction to Multivariate Calibration by Alejandro C. Olivieri

Author:Alejandro C. Olivieri
Language: eng
Format: epub
ISBN: 9783319970974
Publisher: Springer International Publishing

7.8 Real Cases

We first comment in this section on a real case , already studied in the context of CLS: samples containing mixtures of three active principles (rifampicin, isoniazid, and pyrazinamide) were employed to calibrate multivariate models for their determination in pharmaceutical forms (Goicoechea and Olivieri 1999). The CLS model, as discussed in Chap. 2, was unsuccessful, mainly due to the high level of spectral overlapping among the constituent spectra (Fig. 7.5). Using a PLS model, on the other hand, led to satisfactory results (Goicoechea and Olivieri 1999). The analytical results for an independent validation set were considered satisfactory, with average relative errors of 1.9%, 9.2%, and 2.1% for rifampicin, isoniazid, and pyrazinamide, respectively. The largest value corresponded to isoniazid, in agreement with the high degree of overlapping among the spectrum for this particular analyte and the remaining sample constituents.

Fig. 7.5UV-visible absorption spectra of the three pure constituents of a real sample: rifampicin (green line, 6.80 × 10−6 mol L−1), isoniazid (black line, 2.00 × 10−5 mol L−1), and pyrazinamide (red line, 1.20 × 10−4 mol L−1)

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