Liang Yi-zeng

Principle, traits and functions of electrochemical fingerprint of Chinese traditional medicine

In regard to such challenging analysis problems as scientific identification and quality evaluation of Chinese traditional medicine, the electrochemical fingerprint technique of Chinese traditional medicine has been researched. The principle, traits, functions, etc., of the electrochemical fingerprint have detailedly been analyzed and discussed by the B-Z oscillatory system using malonic acid as main dissipation substance, characterized by the fact that different influences of different Chinese traditional medicines on the mechanism of the oscillatory reaction cause different changes of the shape of the potential-time curve of the oscillatory system under the conditions of constant temperature and pressure. An economical, simple and convenient, easy pushing and effective scientific method for distinguishing and evaluating multifarious Chinese traditional medicines has successfully been put forward.

Analysis of volatile chemical components of Radix Paeoniae Rubra by gas chromatography-mass spectrometry and chemometric resolution

The volatile chemical components of Radix Paeoniae Rubra (RPR) were analyzed by gas chromatography-mass spectrometry with the method of heuristic evolving latent projections and overall volume integration. The results show that 38 volatile chemical components of RPR are determined, accounting for 95.21% of total contents of volatile chemical components of RPR. The main volatile chemical components of RPR are (Z, Z)-9,12-octadecadienoic acid, n-hexadecanoic acid, 2-hydroxybenzaldehyde, 1-(2-hydroxy-4-methoxyphenyl)-ethanone, 6,6-dimethyl-bicyclo[3.1.1] heptane-2-methanol, 4,7-dimethyl-benzofuran, 4-(1-methylethenyl)-1-cyclohexene-1-carboxaldehyde, and cyclohexadecane.

Optimization of extraction and determination of emodin from Polygonum cuspidatum Sieb. et Zucc. products by HPLC-DAD

A uniform experimental design procedure was used to investigate the effects of some operating parameters on the extraction of emodin from Polygonum cuspidatum Sieb. et Zucc. products. Variables tested were volume ratio of material to solvent, size of material, extraction time and temperature and composition of extraction solvent (mixtures of acetone-water). Each variable was tested at seven levels; 7 experiments were performed in random order. Analyses of the extracts were performed by high-performance liquid chromatography with diode array detection(HPLC-DAD). Analytical responses were processed by using a forward regression analysis, in order to find polynomial function describing the relationship between variables and responses. For all the analytes the experimental conditions for providing the highest extraction yield inside the experimental domain considered were found. Finally, a simple, rapid and accurate analytical method was developed for the determination of emodin by high performance liquid chromatography. The separation is achieved within 25 min on an ODS column using methanol and water as gradient mobiles. Emodin can be quantified by using external standard method detecting at 436 nm. Good linearity is obtained with correlation coefficient exceeding 0.9986 and the detection limit and the quantification limit are 1.53 and 3.23 mg/L respectively. This method shows good reproducibility for the quantification of the emodin with intra-day and inter-day relative standard deviation less than 2.3% and 5.6% respectively. Under optimized extraction conditions, the recovery of the standard is 96.5%. The validated method is successfully applied to quantify the emodin in seven Polygonum cuspidatum sieb. Et zucc. products, which provided an idea for the pre-treatment of determination of active compounds in traditional Chinese medicines.

Selection of Solvent and Optimization of Programmed Heating Time for Analyzing Cigarette Smoke with GC/oa-TOF-MS

In order to determine the optimum solvent and programmed heating time for analyzing cigarette smoke with GC/oa-TOF-MS method,Shannon information contents,wavelet peak detection and airPLS(adaptive iteratively reweighted Penalized Least Squares) baseline correction were adopted to analyze and evaluate the chromatogram data of tobacco module XA from Honghe in Yunnan and Marlboro and Hongtashan cigarette brands.The results indicated that: 1) Shannon information content and chromatogram information were representable each other,according to the results of differential analysis of different solvent systems;2) Solvent composed of dichloromethane-methanol(2∶1,V/V) obtained better results both in peak areas and in chromatogram information contents;3) With the prolongation of programmed heating time,the separation degree between chromatographic peaks increased and Shannon information contents significantly improved,more information about components involved.Consequently,the established procedures for data processing was suitable for processing GC/oa-TOF-MS data of cigarette smoke,Shannon information contents as well as peak areas could be chosen as the evaluate index to determine the optimum solvent for extraction and programmed heating time.

Relativity Study on Topological Index of Methylalkane Structures and Chromatographic Retention Index

The study of quantitative structure and retention index relationship (QSRR) is an important subject in chromatographic field, which has been used to obtain simple models to explain and predict the chromatographic behavior of various classes of compounds. One hundred twenty-seven topological descriptors of 207 methylalkane structures are calculated and investigated via the quantitative structure-property relationship (QSPR) model in the present paper. GAPLS method, which is a variable selection method combining genetic algorithms (GA), back stepwise, and partial least squares (PLS), is introduced in the variable selection of quantitative structure gas chromatographic (GC) retention index (RI) relationship. Seven topological descriptors are finally selected from 127 topological descriptors by GAPLS method to build a QSRR model with a high regression quality of squared correlation coefficient (R2) of 0.99998 and standard deviation (S) of 2.88. The errors of the model are quite close to the experimental errors. The validation of the model is then checked by leave-one-out cross-validation technique. The results of leave-one-out cross-validation indicate that the built model is reliable and stable with high prediction quality, such as squared correlation coefficient of leave-one-out (Rcv2) of 0.99997 and standard deviation of leave-one-out predictions (Scv) of 2.95. A successful interpretation of the complex relationship between GC RIs of methyalkanes and the chemical structure is achieved using the QSPR method. The seven variables in the model are also rationally interpreted, which indicates that methylalkanes’ RI is precisely represented by topological descriptors.

Direct rapid determination of traces of sulfide in environment samples

An improved ethylene blue method for determination of sulfide is developed. It has been adapted to a direct determination of sulfide by both common spectrophotometric method and total differential spectrophotometric method. In common spectrophotometric method, the calibration curve is A=1.69ρ+0.006 and the correlation coefficient is 0.9994. The apparent molar absorptivity is 5.42 × 104 L·mol−1·cm−1 and calibration curve is liner when ρ is in the range of 0–0.9 mg·L−1. In total differential spectrophotometric method, the calibration curve is A=9.25ρ + 0.004 and the correlation coefficient is 0.9996. The apparent molar absorptivity is 2.96 × 105 L·mol−1 L·mol−1·cm−1 and calibration curve is liner when ρ is in the range of 0–0.10 mg·L−1. The sensitivity of this method is increased significantly compared with the former ethylene blue method. The speed of reaction is also faster than the former one. The limit of detection is found to be 1.0 ng·mL−1 by both common spectrophotometric method and total differential spectrophotometric method. Ten replicate analyses of a sample solution containing 100 ng·mL−1 sulfide give a relative standard deviation of 1.8%. The effects of various cations and anions on the determination of sulfide are studied and procedures for removal of interference is described. The method is used for the determination of sulfide in environment samples with satisfactory results.