Systematical NMR analysis of swainsonine, a mycotoxin from endophytic fungus Alternaria oxytropis.

Swainsonine (SW, 1), a unique indolizine with poly-hydroxyl groups, was re-isolated from the plant endophytic fungus Alternaria oxytropis. The structure (including planar structure and relative configuration) was systematically elucidated by NMR spectra (including 1 H, 13 C, 1 H-1 H COSY, HMQC, HMBC, and NOESY spectra in DMSO-d6 and in CD3 OD); 1 H NMR spectra of the modified Mosher's products were first used to determine the absolute configuration of SW. More importantly, the complex coupled features of H-7α, H-7ß, and H-6α in the 1 H NMR spectrum of (1) were analyzed in details, which will provide aids for the planar and relative configuration determination of analogs.

Development and evaluation of microwave-assisted and ultrasound-assisted methods based on a quick, easy, cheap, effective, rugged, and safe sample preparation approach for the determination of bisphenol analogues in serum and sediments.

Microwave- and ultrasound-assisted methods based on a quick, easy, cheap, effective, rugged, and safe sample preparation approach followed by high-performance liquid chromatography with tandem mass spectrometry were developed for the simultaneous determination of eight bisphenol analogues in serum and sediment. The developed methods provided satisfactory extraction efficiency for the energy provided by microwaves and ultrasound. Compositions of commercial sorbents (primary secondary amine, MgSO4 , octadecyl-modified silica, and graphitized carbon black) were evaluated. The ultrasound-assisted method was suited for serum using primary secondary amine, MgSO4 , and octadecyl-modified silica as sorbents and a mixture of hexane and ethyl acetate as extraction solvent. The microwave-assisted method worked better for sediment with tetrahydrofuran and methanol as solvents and primary secondary amine, MgSO4 , octadecyl-modified silica, and graphitized carbon black as sorbents. Other experimental parameters, such as extraction temperature and time, were also optimized. The inter- and intraday relative standard deviations ranged from 2.7 to 5.5%. The limits of detection were between 0.1 and 1.0 ng/mL for serum and between 0.1 and 0.5 ng/g dry weight for sediment. The proposed methods were successfully applied to seven sediment and 20 human serum samples. The results showed that the developed methods were practical for the analysis and biomonitoring of bisphenols in sera and sediment.

Development, comparison and application of sorbent-assisted accelerated solvent extraction, microwave-assisted extraction and ultrasonic-assisted extraction for the determination of polybrominated diphenyl ethers in sediments.

Fast and selective analytical methods were developed based on sorbent-assisted mechanism and microwave-assisted extraction (SA-MAE), accelerate solvent extraction (SA-ASE) and ultrasonic-assisted extraction (SA-UAE) for the determination of polybrominated diphenyl ethers (PBDEs) in sediments. The experimental parameters, such as extraction conditions and sorbent amounts, were optimized according to Taguchi Orthogonal Arrays. The accuracy of developed SA-methods was a satisfactory ranging from 71% to 118%. The inter/intra-day RSDs were <10% indicating a good method precision. The limits of quantification (LOQ) for target BDEs were ≤1.0ng/g dry weight (dw) with an exception of BDE 209 which was 10.0ng/g dw. The proposed methods were validated by the analysis of PBDEs in standard reference materials (SRM 1944) and the method performances were compared with each other. The results approved the feasibility of SA-methods for PBDEs analysis in sediments. Meanwhile, the optimization processes indicated the mixed sorbents mainly worked on matrix effects elimination. The compositions of sorbents deserved careful optimization because different characteristics of the matrix and extraction intensity may produce various matrix effects. In addition, the developed SA-ASE method was successfully applied on real environmental samples collected from a typical polluted area. The data and calculation suggested local environmental contamination pattern and potential pollution source.