[Kinetic study on pyrolysis of psoralen].

In this study, products of psoralen pyrolysis were detected using a solid pyrolysis apparatus and synchrotron radiation vacuum ultraviolet photoionization mass spectrum (SVUV-PIMS). The pyrolytic kinetics of psoralen was also studied by calculating its initial pyrolytic route in quantum chemistry. According to the findings with SVUV-PIMS, three pyrolytic products were observed, CO, C9H6O and C10H6O2. Theoretically, three fragment pathways were calculated for psoralen, in which the major primary decomposition route was de-CO, and the major secondary decomposition reaction was de-CO reaction of de-CO products.

[Multi-component quantitative method of Chinese herbal additives based on fingerprint].

OBJECTIVE: To establish a full-quantified fingerprint method for analyzing Chinese herbal additives by HPLC. METHOD: A HPLC in combination with PDA detector was applied with a phenomenex luna C18 (4.6 mm x 250 mm, 5 microm) column by gradient elution using acetonitrile-0.1% formic acid solution as the mobile phase. The flow rate was 1 mL x min(-1) and the detection wavelength was set at full spectrum scan. RESULT: According to the selected chromatographic conditions, the full-quantified fingerprint of the Chinese herbal additive has good precision, reproducibility, stability and recovery. CONCLUSION: The HPLC method developed for simultaneous determination of seven compounds is simple and valid. It can be used for quality evaluation and quality control of Chinese herbal additive and its processing products.

Development of the space-resolved solid-phase microextraction technique and its application to biological matrices.

To facilitate rapid in situ analyte monitoring within heterogeneous samples, a space-resolved solid phase microextraction (SR-SPME) technique was developed that utilized miniaturized segmented fibers. Initially, a multilayered agarose gel was used to determine the effects of diffusion-based mass transfer and fiber dimension on the space-resolving capability of SPME. For diazepam within agarose gel, the SR-SPME limit of detection was 2.5 ng/mL, with a linear dynamic range up to 500 ng/mL. The efficacy of the SR-SPME technique was further evaluated within diverse biological matrices (onion bulb, fish muscle, and adipose tissues) containing stratified pharmaceutical analytes. Empirically, the results agreed well with established techniques such as microdialysis and liquid extraction, but SR-SPME was simpler to implement, displayed higher spatial resolution, and was more cost-effective than traditional approaches. Additionally, the segmented design of the SPME fibers and stepwise desorption protocols offer potential advantages within high throughput applications.

Dynamic ultrasound-assisted extraction of catechins and caffeine in some tea samples.

A novel dynamic ultrasound-assisted extraction (DUAE) device has been constructed for extraction of five catechins and caffeine in solid sample. The accurate, simple, reproducible and sensitive method for the determination of five catechins and caffeine has been developed and validated. A comparison has been made of the efficiencies by employing DUAE and conventionally static ultrasound-assisted extraction (UAE). The proposed method can not only improve extraction efficiency but also decrease time and solvent consumption. The commercial Chinese tea samples, involving green and black teas, are rapidly analyzed by the proposed DUAE method. The linearity, range, selectivity, precision, accuracy, and robustness also showed acceptable values.

Two-step simultaneous distillation and solvent extraction for isolation both free and bound aroma in tobacco.

In this investigation, a novel two-step simultaneous distillation and solvent extraction (two-step SDE) method was developed to isolate both free and bound aroma in tobacco. Firstly, free aroma were extracted into dichloromethane by SDE for 4 h with SDE sample solution at pH 5.5. Then the SDE sample solution was adjusted to pH 2.5, bound aroma were hydrolyzed, and released as free aroma extracted by fresh dichloromethane. Following, both the free and bound aroma were analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The whole isolation procedure of both free and bound aroma was carried out in one SDE apparatus and using one same sample. Especially, the procedure of isolation of bound aroma was greatly simplified. To apply and validate the proposed two-step SDE method, a traditional method were also used to isolate the bound aroma. The total bound aroma obtained by the proposed two-step SDE method and the traditional method were 119.83 mg kg(-1) and 88.9 mg kg(-1), respectively. For isolation of bound aroma, the proposed two-step SDE method was of better extraction recovery, less labourious, solvent and time consuming than the traditional method.

Matrix solid phase dispersion-Soxhlet simultaneous extraction clean-up for determination of organochlorine pesticide residues in tobacco.

A novel method combining matrix solid phase dispersion (MSPD) with Soxhlet simultaneous extraction clean-up (SSEC) was developed. Being a single-step extraction and clean-up procedure, it could be used instead of multistep solvent extraction and Florisol column clean-up. It not only reduces sample contamination during the procedure, but it also decreases the amount of organic solvent needed. The retention times of standards were used to qualitatively assess the method, and the external standard method was used to quantitatively assess it. Residues of organochlorine pesticides (OCP) in tobaccos were determined by gas chromatography-electron capture detection (GC-ECD), and their identities were confirmed by the standard addition method (SAM). The performance of the method was evaluated and validated: the detection limit was 0.01-0.02 microg g(-1), relative standard deviations were 5-26%, and recoveries were 72-99% at fortification levels of 0.10, 1.00 and 10.0 microg g(-1). The analytical characteristics of MSPD-SSEC compared very favorably with the results from the classical multistep solvent extraction and Florisol column clean-up method.

[Analysis of essential oil components by GC/FTIR and GC/MS].

The volatile components of clary sage (Salvia sclarea L.) oil were identified by gas chromatography-Fourier transform infrared spectroscopy (GC/FTIR) and gas chromatography-mass spectrometry (GC/MS). The application of GC/FTIR in analysis of essential oil was mainly discussed. The accuracy of qualitative analysis for essential oil was improved by such technique asthe reconstruction of different spectra regions Gram-Schmidt Fourier transforms infrared spectroscopy, and the application of subtracting of Fourier transforms infrared spectroscopy, and the mass spectrometry.