Polysaccharides as separation media for the separation of proteins, peptides and stereoisomers of amino acids.

Reliable separation of peptides, amino acids and proteins as accurate as possible with the maximum conformation and biological activity is crucial and essential for drug discovery. Polysaccharide, as one of the most abundant natural biopolymers with optical activity on earth, is easy to be functionalized due to lots of hydroxyl groups on glucose units. Over the last few decades, polysaccharide derivatives are gradually employed as effective separation media. The highly-ordered helical structure contributes to complex, diverse molecular recognition ability, allowing polysaccharide derivatives to selectively interact with different analytes. This article reviews the development, application and prospects of polysaccharides as separation media in the separation of proteins, peptides and amino acids in recent years. The chiral molecules mechanism, advantages, limitations, development status and challenges faced by polysaccharides as separation media in molecular recognition are summarized. Meanwhile, the direction of its continued development and future prospects are also discussed.

Modification of corn starch via innovative contactless thermal effect from induced electric field.

Growing attention has been focused on modifications of starch using electric field, but electrode corrosion and metal contamination remain unavoidable during the process. To solve these problems, the magneto-induced electric field was used to assist corn starch hydrolysis due to its thermal effect. Results indicated that the method accelerated corn starch acid hydrolysis and decreased the treatment time. The reducing sugar content increased to 0.59 g/L after a 60 s treatment, which was 353.44 % higher than the 20 s treatment, while the average degree of polymerization reached a minimum. The treated starch showed increased solubility and swelling power, as well as decreased freeze-thaw stability. X-ray diffraction, fourier transform infrared spectroscopy, and scanning electron microscopy results suggested that the physicochemical changes of corn starch were due to the thermal effect of the induced electric field. This study is expected to provide an important basis for applying new electric field hydrolysis technology to starch modification.

[Analysis of nonylphenol, octylphenol and bisphenol A in animal tissues by liquid chromatography-tandem mass spectrometry with accelerated solvent extraction].

A comprehensive analytical method based on liquid chromatography-electrospray ionization tandem mass spectrometry with negative ionization mode has been developed for measuring alkylphenols (AP) and bisphenol A (BPA) in animal tissues. Samples of animal tissues were extracted by accelerated solvent extraction with dichloromethane. Sample concentration and purification were performed using an OASIS NH2 solid extraction cartridge. The effects of mobile phase and additives on ionization were assessed. The recoveries for the compounds ranged from 88% to 101% and the relative standard deviations were below 15%. The detection limits of the method under multiple-reaction monitoring mode were 0.3, 0.05 and 0.1 microg/kg for BPA, nonylphenol (NP) and octylphenol (OP), respectively. The contents of NP ranging from 0.49 to 55.98 microg/kg were found in 27 real samples of animal tissues from Beijing market. The results indicate that the endocrine disrupting nonylphenol is ubiquitous in food of animal origin. Nonylphenol was found in all fish samples with concentration levels ranging from 9. 13 to 55.98 microg/kg.

[Determination of estrogen-like compounds in beverages by high performance liquid chromatography].

A comprehensive analytical method based on high performance liquid chromatography-ultraviolet-fluorescence detection (HPLC-UV-FL) has been established for the determination of bisphenol A (BPA), nonylphenol (NP) and octylphenol (OP) in beverages with different samples and concentrations. Clean-up of samples was performed on an OASIS HLB solid extraction cartridges (6 mL, 200 mg). The method was successfully applied to the investigation of residual bisphenol A, nonylphenol and octylphenol in the beverages (mineral waters and soft drinks) available in commercial markets in Beijing. Recoveries for bisphenol A, nonylphenol and octylphenol at different spiked levels were ranged from 91.08% to 103.19% with relative standard deviations of 0.5% to 5.49%. The method is simple with good reproducibility and selectivity, and high sensitivity.