Guo-Sheng Yang

Progress in Quality Control of Herbal Medicine with IR Fingerprint Spectra

Abstract The efficiencies of herbal medicines depend on the amount of active components in them, which could vary significantly in contents. Therefore, the quality control of herbal medicines is a very important issue. This review summarizes the true and false, producing region identification and quality evaluation of herbal medicines by means of their component overlapping infrared spectra (defined as infrared fingerprint spectra or IR FPS). The true and false identification could be performed with specific peaks and their absorption ratios. The producing region and quality of herbal medicines could be determined by analyzing the IR FPS with mathematical classification methods, such as potential component analysis, cluster analysis, and correlation coefficient analysis.

Influence of the Structure of Organic Phosphonate Compounds on Chiral Separation on a Pirkle Type Chiral Stationary Phase

SummaryThe enantiomers of eightO,O-dialkyl-2-benzyloxycarbonyl-aminoarylmethyl-phosphonates are directly separated on anN-(3,5-dinitrobenzoyl)leucine (DNBleu) column. The influence of the mobile phase composition and the column temperature on the retention and the enantioselectivity are investigated. The influence of the length and steric hindrance of alkoxyl groups of the phosphonate ester and the nature of the substituentp-Cl and pH on the benzene ring which is attached to the chiral carbon atom on chiral separation are discussed also.

Hplc enantiomeric separation of o, o-dialkyl-2-benzyloxycarbonyl-aminoarylmethyl-phosphonates on cellulose tris(3,5-dimethylphenyl carbamate) and N-(3,5-dinitrobenzoyl) leucine CSPs

A series of racemic nine o,o-dialkyl-2-benzyloxycarbonyl-aminoarylmethyl-phosphonate enantiomers has been separated by high performance liquid chromatography on cellulose tri(3,5-dimethyl-phenylcarbamate) and N-(3,5-dinitrobenzoyl) leucine (DNB-leu) chiral stationary phases. The chromatographic parameters, the capacity factor (k), separation factor (α), and the resolution factor (Rs) of all solutes are presented. The influence of the mobile phase composition on the enantioselectivity has been discussed.

The study of chiral discrimination of organophosphonate derivatives on pirkle type chiral stationary phase by molecular modeling

Molecular modeling and molecular dynamics (MD) have been used to study the chiral discrimination and interaction energy of organophosphonate in N-(3,5-dinitrobenzoyl)-S-leucine chiral stationary phase (CSP). The elution order of the enantiomers can be predicted from the interaction energy. Quantitative structure-retention relationship (QSRR) has also been used as an alternative method to confirm the elution order of enantiomers. Molecular mechanics (MM), molecular dynamics and QSRR proved to be useful methods to study chiral discrimination.

Simultaneous analysis of kasugamycin and validamycin-A in fruits and vegetables using liquid chromatography-tandem mass spectrometry and consecutive solid-phase extraction

A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for simultaneous determination of two hydrophilic aminoglycosides, kasugamycin and validamycin-A, in a variety of matrices (apples, cabbage, cucumbers, lettuce, tomatoes, and eggplant) has been developed. The proposed method provides sufficient sensitivity and excellent chromatographic performance using a special ReproSil 100 C18 column with 0.1% formic acid as the mobile phase additive. Accurate mass information for both analytes was obtained based on time-of-flight (TOF) mass spectrometry. The methanol/water (70 : 30, v/v) with pH adjusted to 5.5 was selected as the extraction solvent. The combination of hydrophilic–hydrophobic-balanced (HLB) cartridges with strong cation exchange SCX cartridges was used to purify the extracts with strongly polar compounds and satisfactory results were obtained. The consecutive solid-phase extraction minimized signal suppression/enhancement which led to matrix effects in the range of −12.6 to 6.11% only. Recovery experiments were performed for both compounds at three levels (50, 100, and 500 μg kg−1) in six different matrices and yielded good recoveries ranging from 81.7% to 108% with relative standard deviation values below 13%. The limits of quantification (LOQs) for kasugamycin and validamycin-A were 4.1 μg kg−1 and 1.0 μg kg−1, respectively.

Reduction of matrix effects through a simplified QuEChERS method and using small injection volumes in a LC-MS/MS system for the determination of 28 pesticides in fruits and vegetables

A simplified QuEChERS method coupled with a small injection volume was developed for the simultaneous determination of 28 pesticides in 6 matrices (apples, cucumbers, tomatoes, luffa, cabbages, and eggplants) using LC-MS/MS. In the sample procedure, acetonitrile with 0.1% (v/v) formic acid was used to extract and no depurative powder was used. Three fortified levels (10, 50, and 100 μg kg−1) were determined and the recoveries of 168 analyte/matrix combinations were in the range of 60–120% except for cyromazin, pendimethalin, and fenpropathrin. Half of the 168 LOQs were below 0.1 μg kg−1, and 29 LOQs were above 1 μg kg−1. Moreover, four relationships between signal suppression and injection volume were observed ranging from 0.5 μL to 15 μL. For many analyte/matrix combinations, the matrix effects could be reduced to less than 20% if the injection volume was less than a critical value (named critical volume). The critical volume depending on the initial extent of matrix effects was explored and the conclusion was: for weak or medium MEs, usually ≤2 μL injection volume was needed and for several weak MEs, injection volume ≤ 5 μL can reduce the matrix effect to a negligible level.

Enantioseparation of Four Organophosphonate Derivatives on N‐(3,5‐Dinitrobenzoyl)‐ l‐leucine–n‐Propylamide Stationary Phase by Molecular Modeling

Four groups of organophosphonate derivatives enantiomers were separated on N-(3,5-dinitrobenzoyl)-S-leucine chiral stationary phase. The three-dimensional structures of the complexes between the single enantiotopic chiral compounds and chiral stationary phase have been studied using molecular model and molecular dynamics simulation. Detailed results regarding the conformation, auto-docking, and thermodynamic estimation are presented. The elution order of the enantiomer could be determined from the energy. The predicted chiral discrimination was obtained by computational results.

Enantiomeric Separation of Several Oxirane Derivatives by High Performance Liquid Chromatography on Polysaccharide-Based Chiral Stationary Phases

Abstract Five polysaccharide based chiral stationary phases have been used for separation of enantiomers of fourteen heterocyclic oxiranes. The polysaccharide based chiral stationary phases used in this study are Chiralak AD, Chiralpak AS, Chiralcel OD, Chiralcel OG, and Chiralcel OJ. From the chiral separation results, the chiral separation ability for the selected compounds show the order of Chiralpak AD > Chiralcel OD > Chiralcel OJ > Chiralcel OG > Chiralpak AS. Chiralcel OD appears to be quite versatile, since 8 out of 11 oxiranes with π-aromatic system were successfully resolved, yet no resolution was obtained for those oxirane derivatives, which lacks the π-aromatic system. Although Chiralcel OD is also versatile, it was not as effective; since the separation factors (α) are much smaller. The results indicate that dipole interactions have a strong impact on the retention mechanism, and extended π systems are essential. The spatial arrangement of the substituent groups around the analyte stereogenic center plays an important role in enantiomeric separations. The closer a group is to the chiral center, the more likely is the chiral recognition and enantioselectivity.

Study of Elution Order in Chiral Separation of Organophosphonate Esters Using Tris-(3,5-dimethylphenyl Carbamate) Cellulose Chiral Stationary Phase by HPLC

Abstract It is known that the separation of several organic phosphonate esters using a tris(3,5-dimethylphenyl carbamate) cellulose (Chiralcel OD) column are better than the separation obtained using the Pirkle type chiral stationary phase (CSP), namely the N-(3,5-dinitrobenzoyl) leucine column. However, the elution order of the organic phosphonate esters enantiomers separated on tris(3,5-dimethylphenyl carbamate) cellulose chiral stationary phase is not known. The tandem use of these two CSPs together showed that the R-enantiomer had shorter retention time than S-enantiomer when tris(3,5-dimethylphenyl carbamate) cellulose chiral stationary phase was used.

Study on 1HNMR Fingerprint Spectra of Tea by Common and Variation Peak Ratio Dual-Index Sequence Analysis Method

Abstract This paper describes the application of the common and variation peak ratio dual-index sequence analysis methods to evaluate the quality of several tea samples obtained from different species and different areas based on 1HNMR fingerprint spectra (FPS). The method is able to determine the most similar sample groups and identify accurately the varieties and qualities of Blank tea, Longjing tea, and other green tea samples. Longjing tea is a famous brand of local green tea and has its own distinct characteristics. There were obvious differences between Uji tea from Japanese and Chinese green tea. The results showed that the dual index sequent analytical method provides a good approach to accurately describe the resemblance and differences among tea samples. It also can reflect teas integrity and individual difference, and is an effective method to evaluate the quality of tea samples.