POSTER: Transfer of a chiral CE method using precision and robustness testing data

info:eu-repo/semantics/nonPublishe

POSTER: Transfer of a chiral CE method using precision and robustness testing data

info:eu-repo/semantics/nonPublishe

POSTER: Inter-instrumental transfer of a chiral CE method using precision studies and robustness testing data,

info:eu-repo/semantics/nonPublishe

Quality control of Citri reticulatae pericarpium: Exploratory analysis and discrimination.

Extracts of Citri reticulatae pericarpium (PCR) are commonly used in the Traditional Chinese Medicine. The quality control of PCR is currently performed by single marker analysis, which can hardly describe the complexity of such natural samples. In this study, a fingerprint methodology for PCR based on high-performance liquid chromatography (HPLC) was developed and validated. A total of 69 fingerprints of authenticated PCR samples, commercial PCR samples, mixed peel samples, and other Citrus peels were recorded. Exploratory data analysis allowed optimizing the extraction procedure and detecting mixed peel samples. Once the optimizations were performed and the method validated, discrimination between the authentic PCR samples and all other samples was performed by p-Discriminant Partial Least Squares. The established model was able to differentiate between classes with a high reliability for each sample. Furthermore, evaluation of the score and loading plots of the model indicated nobiletin, tangeretin, naringin and hesperidin as important markers for the quality control of PCR

Accuracy profiles assessing the validity for routine use of high-performance thin-layer chromatographic assays for drug formulations

The accuracy profile, based on total error, integrates several validation parameters, such as trueness, precision and linearity, providing one statistic which enables decision on the suitability of a method for its intended purpose. Two assay methods for formulations are validated using accuracy profiles as an alternative approach to classic method validation. It concerns high-performance thin-layer chromatography (HPTLC) methods, which initially were validated using the classic approach. The first method assayed sulfamethoxazole and trimethoprim, and the second lamivudine, stavudine and nevirapine. Both formulations are fixed-dose combination tablets. The resulting accuracy profiles showed that the 95% beta-expectation tolerance limits for all compounds fell well within the bias acceptance limits set at +/-5%. This means that the two analytical thin-layer chromatographic methods are capable of making accurate results at the studied concentration ranges of each compound. Measurement uncertainties of every compound at each concentration level could also be determined from the accuracy profile data</p

Potential antioxidant compounds in Mallotus species fingerprints. Part I: Indication, using linear multivariate calibration techniques

Some Mallotus species are used in traditional medicine in Vietnam and China. Some also show interesting activities, such as antioxidant and cytotoxic ones. Combining fingerprint technology with data-handling techniques allows indicating the peaks potentially responsible for given activities. In this study it is aspired to indicate from chromatographic fingerprints the peaks potentially responsible for the antioxidant activity of several Mallotus species. Relevant information was extracted using linear multivariate calibration techniques, both before and after alignment of the fingerprints with correlation optimized warping (COW). From the studied techniques, Stepwise Multiple Linear Regression is least recommended as it made an inadequate variable selection. Principal Component Regression theoretically can take largely varying variables uncorrelated to the antioxidant activity into account. However, in practice in the actual case study this problem was limited. These problems in principle do not occur using Partial Least Squares (PLS) models. Of the tested PLS methods, Orthogonal Projections to Latent Structures was preferred because of its simplicity, reproducibility, reduced model complexity and improved interpretability of the regression coefficients, yielding a clearer view on the individual contribution of the compounds. Furthermore, reducing analysis times from 60 min to 35 and 22.5 min resulted in the same main compounds, indicated responsible for the antioxidant activity. Models built after alignment by COW did not result in additional information