Search

A simple, efficient, and green chitosan-assisted liquid-solid extraction method was developed for the sample preparation of isoquinoline derivative alkaloids followed by microemulsion LC. The optimized mobile phase consisted of 0.8% w/v of ethyl acetate, 1.0% w/v of SDS, 8.0% w/v of n-butanol, 0.1% v/v acetic acid, and 10% v/v ACN. Compared to pharmacopoeia method and organic solvent extraction, this new approach avoided the use of volatile organic solvents, replacing them with relatively small amounts of chitosan. Under the optimum conditions, good linearity (r 2 > 0.9980) for all calibration curves and low detection limits between 0.05 and 0.10 μg/mL were achieved. The presented procedure was successfully applied to determine alkaloids in Rhizoma coptidis with satisfactory recoveries (81.3-106.4%)., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A green and economical method for the extraction and preconcentration of natural pigments (curcumin, demethoxycurcumin and bisdemethoxycurcumin) was developed using ultrasound-assisted extraction combined with dispersive micro solid-phase extraction. In this work, Ionic liquids (ILs) were used for the pre-extraction of natural pigments. The pure chitosan nanoparticles (CS NPs) were then used as a sorbent for the microextraction mode. The method involves the use of ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry. Operating parameters influencing the performance of extraction steps such as type and concentration of ILs, concentration of CS NPs, type of elution solvent, agitation time and pH of sample-extracting solution were investigated. Under the optimum conditions, the proposed method exhibited a low detection limit in the range of 0.11-0.36ng/mL at S/N=3, and good linearities with coefficients of determination (R(2)) higher than 0.9990. The recoveries of turmeric samples were ranging from 90.45% to 105.04% for the three studied curcuminoids with SD of 3.27-6.58. The experimental results indicated that the ILs and CS NPs were the promising materials for the extraction and enrichment of target curcuminoids from complex solid samples., (Copyright © 2016 Elsevier B.V. All rights reserved.)

A simple, efficient and low-cost method based on matrix solid-phase dispersion (MSPD) microextraction and ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (UHPLC-Q-TOF/MS) was developed for the determination of seven main natural phenols (gallic acid, hydroxytyrosol, methyl gallate, luteolin 7-O-β-d-glucoside, rutin, ellagic acid and oleuropein) and other eleven compounds in olive fruits. The experimental conditions for the MSPD extraction, including the type of adsorbent, the amount of dispersing sorbent, the grinding time, and the type of elution solvent were investigated and optimized. The optimized parameters were determined to be that middle-molecular-weight chitosan was used as adsorbent, the amount of middle-molecular-weight chitosan was selected to be 25mg, the grinding time was chosen to be 60s, and methanol: water (6:4, v:v) was used as elution solvent. Compared with reported methods, the proposed method was more simple, rapid, and efficient. Moreover, this method required less extraction time and less amount of sample and solvent. The method showed good linearity (r(2)≥0.9909) for the seven analytes, with the limits of detection in the range of 69.6-358.4ng/g. And recoveries were above 80.06%. The methodology was successfully applied to the extraction and determination of seven phenolic compounds in olive fruits（Canarii fructus）., (Copyright © 2016 Elsevier B.V. All rights reserved.)

A rapid, simple, and strongly selective miniaturized solid phase extraction (SPE) technique, requiring only small amounts of sorbent (24 mg) and elution solvent (600 μL), coupled with ultrahigh-performance liquid chromatography and quadrupole time-of-flight mass spectrometry was developed for detecting tetracycline antibiotics. These analytes were extracted from honey and milk using chitosan-modified graphitized multiwalled carbon nanotubes (G-MWNTs) as the solid sorbent and acetonitrile/acetic acid (8:2, v/v) as the eluent in miniaturized SPE. Under the optimum experimental conditions, a satisfactory linearity (r(2) > 0.992) was obtained, and the limits of detection were in the range of 0.61-10.34 μg/kg for the analytes. The mean recoveries of the five tetracycline antibiotic residues in the real samples were between 81.5 and 101.4%. The results demonstrated that chitosan-modified G-MWNTs comprise a promising material for the enrichment of tetracycline antibiotics from complex food matrices.