Aplicação da espectrometria de massas com ionização por paper spray na diferenciação de amostras de ginsengs e quantificação de adulterações usando calibração multivariada

Abstract

Ginseng is worldwide consumed due to its medicinal properties. The Korean and American ginsengs belong to the genus Panax while the Brazilian to the genus Pfaffia. They may have distincts therapeutic effects since they have different chemical components. The Korean ginseng (Panax ginseng) and the American ginseng (Panax quinquefolius) possess chemical compounds called ginsenosides, whose areresponsible for the therapeutic effects of the medicinal plant. These components are absent in the Brazilian ginseng (Pfaffia paniculata), although its phytochemical characteristics are similar to those of Korean ginseng. In this work, the differentiation of these three ginseng species was carried out by paper spray mass spectrometry (PS-MS). The analyzes were performed with the direct application of 15 L of ginseng extract on a chromatography paper cut into a triangle shape, followed by the application of 4.5 kV potencial on the basis of the paper, whichwas positioned at a distance of 7 mm from the MS inlet. The differentiation was performed by comparing the mass spectra of the different ginseng species, by means of a chemical fingerprint analysis. The results showed that in the mass range of m/z 100-1500, with ions of m/z 156, 543, 705, 867, 1029 and 1119 were only observed for Brazilian ginseng samples, which allowed differentiation with the samples of the genus Panax (Korean and American ginsengs). For differentiating samples of the two species of the genus Panax, other ranges were analyzed and MS signals related to ginsenosides were detected. Some ginsenosides were observed in common for bothspecies, such as Rb1 and Rc/Rb2. MS signals ascribed to ginsenosides Ra3 (m/z 1263) and Ra1/Ra2 (m/z 1249) were detected only for P. ginseng species. In contrast, only in American ginseng samples, P. quinquefolius, MS signals ascribed to ginsenosides Rg1and Rd were noticed. In addition, in the American ginseng, the relative abundance of the ion m/z 1117 was lower than that the of ion m/z 1147 in all samples, while all the Korean ginseng samples showed these intensities of signals much closer. Furthermore, quantification of adulteration from Korean ginseng with Brazilian ginseng was carried out using multivariate calibration, Partial Least Squares (PLS), withthe data obtained by PS-MS. The model was built with 55 adulterated samples (7-58% w/w), split in 39 and 16 samples for calibration and validation sets, respectivelly. The model showed root mean square errors of prediticion (RMSEP) and of calibration (RMSEC) of 3.97 and 2.16% w/w, respectively. The method was validated and it was linear, sensitive, unbiased and showed a Residual Prediction Deviation (RPD) forcalibration and validation of 3.9 and 3.5, respectively.