Extraction,separation and quantitative structure–retention relationship modeling of essential oils in three herbs

The essential oils extracted from three kinds of herbs were separated by a 5% phenylmethyl silicone (DB‐5MS) bonded phase fused‐silica capillary column and identified by MS. Seventy‐four of the compounds identified were selected as origin data, and their chemical structure and gas chromatographic retention times (RT) were performed to build a quantitative structure–retention relationship model by genetic algorithm and multiple linear regressions analysis. The predictive ability of the model was verified by internal validation (leave‐one‐out, fivefold, cross‐validation and Y‐scrambling). As for external validation, the model was also applied to predict the gas chromatographic RT of the 14 volatile compounds not used for model development from essential oil of Radix angelicae sinensis. The applicability domain was checked by the leverage approach to verify prediction reliability. The results obtained using several validations indicated that the best quantitative structure–retention relationship model was robust and satisfactory, could provide a feasible and effective tool for predicting the gas chromatographic RT of volatile compounds and could be also applied to help in identifying the compound with the same gas chromatographic RT.     

Synthesis and structure‐optoelectronic property relationships of a series of PPV and SFTV derived polymers

Engineering of the highest occupied molecular orbital and lowest unoccupied molecular orbitals through synthetic chemical structural modification has been the most widely used method to tuning optoelectronic properties in conjugated polymers. The electronic, thermal, optical, and physical properties can be tuned and exploited for optimization of optoelectronic devices. Through copolymerization of donor and acceptor type conjugated monomers, the frontier orbitals of four polymers were tailored. Through this synthetic engineering, the relationship between structural features, frontier orbital tailoring, and changes in optoelectronic and physical properties are discussed. Spectroscopic, thermal, and electronic analysis of the polymers indicated that polymers containing carbazole monomer moieties gave overall improved optoelectronic properties, but higher band gaps (2.61 and 2.18 eV) in comparison to their phenyl‐ based counterparts. This result is attributed to the higher electron density of the carbazole than the terephthaldicarboxaldehyde, and the possible deviation from planarity in the polymer main chain due to possible steric hindrance of the branched substituents. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2202–2213     

Development of a magnetic solid‐phase extraction coupled with gas chromatography and mass spectrometry method for the analysis of semivolatile organic compounds

Semivolatile organic compounds are a category of organic micropollutants including phthalate esters, polycyclic aromatic hydrocarbons and so on, which are commonly analyzed by solid‐phase extraction followed by gas chromatography with mass spectrometry. In this work, a highly sensitive and feasible method of magnetic solid‐phase extraction combined with gas chromatography with mass spectrometry was established for the determination of semivolatile organic compounds in water. The novel method was based on a permanent magnetic resin with uniform particle size and high surface area (1154.3 m²/g). The results demonstrated that the extraction efficiency of the resin was superior to that of a C₁₈ cartridge. The method was proved to be of satisfactory recoveries (75–115.7%) and limits of detection and quantification (0.063–6.524 and 0.212–21.745 μg/L, respectively). The method was applied to the analysis of semivolatile organic compounds in the midstream Huai River. It was observed that polychlorinated biphenyls exceeded current water standards. To further illustrate the potential effects on human health, health risk assessment was conducted based on the obtained data. The existence of health risk was proved, with hexachlorobenzene and 2,2’,4,4’‐tetrachlorobiphenyl as the major causes. The method possesses the characteristics of high efficiency and rapid analysis, offering a good prospect of applications in large quantities of practical water.     

A sensitive and efficient method for trace analysis of some phenolic compounds using simultaneous derivatization and air‐assisted liquid–liquid microextraction from human urine and plasma samples followed by gas chromatography–nitrogen phosphorous detection

In present study, a simultaneous derivatization and air‐assisted liquid–liquid microextraction method combined with gas chromatography–nitrogen phosphorous detection has been developed for the determination of some phenolic compounds in biological samples. The analytes are derivatized and extracted simultaneously by a fast reaction with 1‐flouro‐2,4‐dinitrobenzene under mild conditions. Under optimal conditions low limits of detection in the range of 0.05–0.34 ng mL^?1 are achievable. The obtained extraction recoveries are between 84 and 97% and the relative standard deviations are less than 7.2% for intraday (n = 6) and interday (n = 4) precisions. The proposed method was demonstrated to be a simple and efficient method for the analysis of phenols in biological samples. Copyright © 2015 John Wiley & Sons, Ltd.     

Evaluation of a novel metal–organic framework as an adsorbent for the extraction of multiclass pesticides from coconut palm (Cocos nucifera L.): An analytical approach using matrix solid‐phase dispersion and liquid chromatography

We report the synthesis, characterization, and application of [Zn(1,4‐benzenedicarboxylate)(H₂O)₂]_n , Zn(1,4‐benzenedicarboxylate)_0.99(NH₂‐1,4‐benzenedicarboxylate)_0.01(H₂O)₂]_n , [Zn(1,4‐benzenedicarboxylate)_0.95(NH₂‐1,4‐benzenedicarboxylate)_0.05(H₂O)₂]_n , and [Zn(1,4‐benzenedicarboxylate)_0.9(NH₂‐1,4‐benzenedicarboxylate)_0.1(H₂O)₂]_n as sorbents for the extraction of multiclass pesticides from coconut palm. Liquid chromatography with ultraviolet diode array detection was used as the analysis technique, and the experiments were performed at one fortification level (0.1 μg/g). The recoveries were 47–67, 51–70, 58–72, and 64–76% for [Zn(1,4‐benzenedicarboxylate)(H₂O)₂]_n , Zn(1,4‐benzenedicarboxylate)_0.99(NH₂‐1,4‐benzenedicarboxylate)_0.01(H₂O)₂]_n , [Zn(1,4‐benzenedicarboxylate)_0.95(NH₂‐1,4‐benzenedicarboxylate)_0.05(H₂O)₂]_n , and [Zn(1,4‐benzenelate)_0.95(NH₂‐1,4‐benzenedicarboxylate)_0.05(H₂O)₂]_n , and [Zn(1,4‐benzenedicarboxylate)_0.9(NH₂‐1,4‐benzenedicarboxylate)_0.1(H₂O)₂]_n , respectively, with relative standard deviation ranging from 1 to 7% (n = 3). Detection and quantification limits were 0.01–0.05 and 0.05–0.2 μg/g, respectively, for the different pesticides studied. The method developed was linear over the range tested (0.01–10.0 μg/g) with r ² > 0.9991. A direct comparison of [Zn(1,4‐benzenedicarboxylate)_0.9(NH₂‐1,4‐benzenedicarboxylate)_0.1(H₂O)₂]_n with the commercially available neutral alumina showed that [Zn(1,4‐benzenedicarboxylate)_0.9(NH₂‐1,4‐benzenedicarboxylate)_0.1(H₂O)₂]_n was a similar extracting phase for the pesticides investigated.