A study of the in-situ CO2 removal pyrolysis of Chinese herb residue for syngas production.

The in-situ CO2 removal pyrolysis of Chinese herb residue was studied by thermodynamic equilibrium simulation and experimental methods. The effects of temperature, pressure, and CaO loading on the gas composition, heating value and yield were determined. The simulation results indicate that the heating value of product gas increases with the increase of Ca/H and pressure, and slightly decreases with the increase of temperature. The simulation results were verified by the experiments conducted with a micro fixed-bed reactor. Under the simulated reaction conditions including atmospheric pressure, reaction temperature of 700 °C and the Ca/H of 0.65, the CO2 in the product gas was effectively removed, resulting the syngas with a high heating value. The product gas was mainly composed of H2, CO, CO2 and CH4 with the contents of 47.52, 22.04, 9.01 and 14.02 respectively by experiment. And the lower heating value of the product gas reached 18.1 MJ/Nm3.

A pre-classification strategy based on UPLC-Triple-TOF/MS for metabolic screening and identification of Radix glehniae in rats.

Traditional Chinese Medicines (TCMs) have gained increasing popularity in modern society. However, the profiles of TCMs in vivo are still unclear owing to their complexity and low level in vivo. In this study, UPLC-Triple-TOF techniques were employed for data acquiring, and a novel pre-classification strategy was developed to rapidly and systematically screen and identify the absorbed constituents and metabolites of TCMs in vivo using Radix glehniae as the research object. In this strategy, pre-classification for absorbed constituents was first performed according to the similarity of their structures. Then representative constituents were elected from every class and analyzed separately to screen non-target absorbed constituents and metabolites in biosamples. This pre-classification strategy is basing on target (known) constituents to screen non-target (unknown) constituents from the massive data acquired by mass spectrometry. Finally, the screened candidate compounds were interpreted and identified based on a predicted metabolic pathway, well - studied fragmentation rules, a predicted metabolic pathway, polarity and retention time of the compounds, and some related literature. With this method, a total of 111 absorbed constituents and metabolites of Radix glehniae in rats' urine, plasma, and bile samples were screened and identified or tentatively characterized successfully. This strategy provides an idea for the screening and identification of the metabolites of other TCMs.

Simultaneous determination of nine coumarins in rat plasma by HPLC-MS/MS for pharmacokinetics studies following oral administration of Fraxini Cortex extract.

A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed for the simultaneous determination of nine coumarins including aesculin, aesculetin, fraxin, fraxetin, scopoletin, isoscopoletin, 6-hydroxy-7,8-dimethoxy coumarin, 8-hydroxy-6,7-dimethoxy coumarin and umbelliferone in rat plasma using nodakenin as the internal standard (IS). The plasma samples were pretreated by a one-step direct protein precipitation with methanol. The chromatographic separation was carried out on a C18 column with a gradient mobile phase consisting of methanol and water (containing 0.05% acetic acid). All analytes and IS were quantitated through electrospray ionization in negative ion multiple reaction monitoring (MRM) mode. This method was fully validated in terms of the sensitivity, specificity, accuracy, precision (intra- and inter-day), matrix effect, recovery as well as the stability of the analyte under various conditions, and the results satisfied the requirements of biological sample measurement. The validated method was successfully applied to pharmacokinetic study of the nine coumarins in rat plasma after oral administration of Fraxini Cortex aqueous extract, among which the pharmacokinetics of four coumarins including fraxetin, isoscopoletin, 6-hydroxy-7,8-dimethoxy coumarin and 8-hydroxy-6,7-dimethoxy coumarin were studied for the first time.

Simultaneous determination of five constituents in Qinpijiegu capsule by high-performance liquid chromatography coupled with tandem mass spectrometry.

A rapid high-performance liquid chromatography coupled with tandem mass spectrometry method was developed for the simultaneous determination of five constituents in Qinpijiegu capsule (QJC), a classical Tibetan prescription. The separation of five compounds such as aesculin, aesculetin, fraxin, peimine and peiminine was performed on a Purospher STAR LP RP-C18 (250 × 4.6 mm, 5 µm) column with linear gradient elution of acetonitrile-0.3‰ formic acid water in 13 min. Detection was carried out by multiple reaction monitoring mode using electrospray ionization in the positive and negative ion switching mode. The sample was prepared with ultrasound extraction with methanol, which could obtain higher extraction efficiency and shorter extraction time comparing to reflux extraction with alkalized chloroform-methanol. The proposed method was applied to analyze three batches of samples with acceptable linearity (r(2) > 0.9977), precision [relative standard deviation (RSD) < 7.40%], repeatability (RSD < 2.49%), stability [relative error (RE) < 9.15%] and recovery (RSD < 10.76%). This is the first development of a multicomponent quantitation method for the quality control of QJC. Furthermore, the new established method was proven to be highly sensitive and effective in evaluating the quality of QJC.

Simultaneous quantification of six constituents in Qing-huo-zhi-mai tablet by high-performance liquid chromatography-tandem mass spectrometry.

A novel sensitive and specific high-performance liquid chromatography-tandem mass spectrometry method was established for the simultaneous determination of six constituents including geniposide, andrographolide, dehydroandrographolide, ophiopogonin D, methylophiopogonanone A and methylophiopogonanone B in Qing-huo-zhi-mai (QHZM) tablet, a well-known Chinese herbal preparation. The chromatographic separation was performed on a C18 column, and the mobile phase was composed of 0.04% acetic acid and acetonitrile with gradient elution. The detection of analytes was carried out by multiple reaction monitoring scanning with switching electrospray ion source polarity between positive and negative modes in a single run. The total run time was 15 min. The calibration curves were linear with all correlation coefficients >0.9979 in the tested ranges. The intra- and interday variations were no >7.0%, and the average recoveries were in the range of 93.2-108.5% with the relative standard deviations no >5.4%. The developed method was successfully employed to analyze five batches of QHZM tablet samples. This is the first time for the determination of ophiopogonin D, methylophiopogonanone A and methylophiopogonanone B in QHZM tablets.

Structural elucidation of stress degradation products of ampicillin sodium by liquid chromatography/hybrid triple quadrupole linear ion trap mass spectrometry and liquid chromatography/hybrid quadrupole time-of-flight mass spectrometry.

RATIONALE: Clinical adverse reactions to ampicillin sodium are closely related to its impurities and degradation products. Several unknown degradation products have been detected in the degradation samples of ampicillin sodium. Therefore, a sensitive and accurate method is required to rapidly identify unknown degradation products. METHODS: Ampicillin sodium was subjected to forced degradation under hydrolytic (acidic and alkaline), hot, photolytic, and humid stress conditions. A combination of liquid chromatography/hybrid triple quadrupole linear ion trap mass spectrometry (LC/QqLIT-MS) and liquid chromatography/hybrid quadrupole time-of-flight mass spectrometry (LC/QqTOF-MS) was used to identify unknown degradation products. The analysis was achieved with gradient elution on an Agilent Zorbax SB-C18 column using ammonium acetate (1 mmol/L, pH 3.5) and acetonitrile. RESULTS: A total of 19 degradation products and impurities, including five novel degradation products, were identified and characterized in the forced conditions. The novel degradation products were separately identified as (Z)-2-amino-N-((2-oxo-3-phenyl-2,3,6,7-tetrahydro-1H-1,4-diazepin-5-yl)methylene)-2-phenylacetamide (m/z 349), 2-(1-(2-amino-2-phenylacetamido)-2-((carboxy(phenyl)methyl)amino)-2-oxoethyl-5,5-dimethyl-4,5-dihydrothiazole-4-carboxylic acid (m/z 499), (E)-2-(((3,6-dioxo-5-phenyl-1,6-dihydropyrazin-2(3H)-ylidene)methyl)amino)-3-mercapto-3-methylbutanoic acid (m/z 348), 5-(amino(phenyl)methyl)-7-formyl-2,2-dimethyl-2,3-dihydroimidazo[5,1-b]thiazole-3-carboxylic acid (m/z 332), and 2-(1-(2-amino-2-phenylacetamido)-2-((2-(((4-carboxy-5,5-dimethylthiazolidin-2-yl)methyl)amino)-2-oxo-1-phenylethyl)amino)-2-oxoethyl)-5,5-dimethylthiazolidine-4-carboxylic acid (m/z 673). CONCLUSIONS: LC/QqTOF-MS allowed us to obtain more accurate, richer information than LC/QqLIT-MS for the qualitative analysis of unknown compounds. Forced degradation studies could provide us with the data needed to understand the degradation pathways and intrinsic stability of drugs, and to simultaneously validate the feasibility of the analytical procedure.

Multi-responses extraction optimization based on response surface methodology combined with polarity switching HPLC-MS/MS for the simultaneous quantitation of 11 compounds in Cortex Fraxini: application to four species of Cortex Fraxini and its 3 confusable species.

A novel polarity switching high performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) approach combining optimization of extraction condition by response surface methodology (RSM) was developed for the simultaneous quantitative analysis of 11 compounds in Cortex Fraxini, a commonly used traditional Chinese medicine. The ultrasonic extraction conditions of the 11 analytes including sample quantity, methanol concentration and extraction time were simultaneously optimized with a Box-Behnken design (BBD) and Derringer's desirability function. Multiple-reaction monitoring (MRM) scanning was employed for quantification with switching electrospray ion source polarity between positive and negative modes in a single run of 16min. Quantitative parameters of the proposed method with respect to limit of detection (LOD), limit of quantification (LOQ), linearity, precision, accuracy and stability were evaluated under optimum conditions, and the results indicated that the method was sensitive, specific and reliable. The developed method was successfully applied to determine the investigated compounds in four species of Cortex Fraxini and three kinds of its confusable species, and significant differences were found between the official and confusable species.

Simultaneous determination of imperatorin and its metabolite xanthotoxol in rat plasma by using HPLC-ESI-MS coupled with hollow fiber liquid phase microextraction.

The objective of the present study was to develop a new method for the simultaneous quantitation of imperatorin and its metabolite xanthotoxol in rat plasma. The samples were prepared with hollow fiber liquid phase microextraction (HF-LPME). The optimized extraction procedure was acquired by assessing extraction solvent, length of the fiber, agitation rate, extraction temperature and time. A comparison of sample pretreatment ways between HF-LPME and deproteinization with methanol was performed, which demonstrated less ion suppression and better sensitivity of HF-LPME. Analytes were separated on a C18 column with a gradient elution consisted of methanol and water containing 1mmol/L ammonium acetate. The detection was accomplished by electrospray ionization (ESI) source operating in the positive ionization mode. Selected-multiple-reaction monitoring (SMRM) scanning was employed, which guaranteed a higher sensitivity compared with MRM mode. Calibration curves were linear over investigated ranges with correlation coefficients greater than 0.9979. Precision varied from 0.26% to 14%, and the accuracy varied within ±5.5%. The developed method was successfully applied to the pharmacokinetic research of imperatorin and its metabolite xanthotoxol after oral administration of imperatorin to rats.