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URI permanente para esta coleçãohttps://locus.ufv.br/handle/123456789/11800
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Item An optimized and validated 1H NMR method for the quantification of α-pinene in essentials oils(Talanta, 2015-10-31) Cerceau, Cristiane I.; Barbosa, Luiz C.A.; Filomeno, Claudinei A.; Alvarenga, Elson S.; Demuner, Antônio J.; Fidencio, Paulo H.The authenticity and composition of commercial essential oils requires strict quality control. Due to the importance of α-pinene containing essential oils, a rapid and efficient method for quantification of this terpene in oils of eucalyptus, pink pepper and turpentine using 1H NMR was developed and validated. All evaluated parameters (selectivity, linearity, accuracy/precision, repeatability, robustness, stability of analyte and internal standard in solutions) showed satisfactory results. The limit of detection (LOD) and limit of quantification (LOQ) were 0.1 and 2.5 mg respectively. These values indicated that α-pinene was detected in 35 mg samples containing at least 0.3% of this compound. In addition, a minimum of 8% of α-pinene in the sample was required for quantification. Furthermore, the standard deviations found in the 1H NMR methodology were less than 1% and were lower than those obtained by gas chromatographic analysis. Statistical tests have shown that the results obtained by 1H NMR methodology are similar to those obtained by GC-FID technique using external and internal standardization and normalization within 95% confidence. R&R values lower than 10% have shown that all the methods are appropriate and the 1H NMR method is suitable for quantification of α-pinene in samples of essential oils since this method possessed the smallest R&R (1.81) value.Item A validated 1 H NMR method for quantitative analysis of α -bisabolol in essential oils of Eremanthus erythropappus(Talanta, 2016-08-10) Cerceau, Cristiane I.; Barbosa, Luiz C.A.; Alvarenga, Elson S.; Ferreira, Antonio G.; Thomasi, Sérgio S.α-Bisabolol is a natural terpene produced by Eremanthus erythropappus and is widely used in cosmetics and pharmaceuticals due to its anti-inflammatory, antibacterial and antimycotic properties. Due to these applications, a control of composition and authenticity of commercial oils rich in this terpene is required, resulting in a demand for new methodologies for quality control. In this work a rapid and efficient method for quantification of α-bisabolol in the essential oil of E. erythropappus (candeia) using 1H NMR was developed, validated and compared to gas chromatography (GC) method. The quantification of α-bisabolol by 1H NMR was successfully achieved for most of the essential oil samples of E. erythropappus evaluated, except for those with a more complex composition. To circumvent this limitation a 2D NMR COSY contour map was used. This method proved to be a fast and efficient alternative, providing results with standard deviations SD<0.3%. All evaluated parameters (selectivity, linearity, accuracy/precision, repeatability, robustness and stability of analyte and internal standard in solution) gave satisfactory results. Using the 1H NMR signals at 5.36 and 5.13 ppm, the limit of detection (LOD) and limit of quantification (LOQ) were 0.26 and 2.59 mg, respectively. The results obtained by the 1H NMR method presented SD=0.59%, smaller than the value found for GC (SD=1.18%). Tukey tests have shown that the results obtained by 1H NMR and COSY methodology are similar to the obtained by the traditional GC-FID technique using external and internal standardization and normalization with 95% confidence.