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Abstract: A novel highly hydrophilic polymethacrylate-based monolithic stationary phase based on the copolymerization of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) and pentaerythritol triacrylate (PETA) was designed for pressurized capillary electrochromatography. A typical hydrophilic interaction chromatography mechanism could be observed when the content of acetonitrile (ACN) in the mobile phase exceeded 25%. Slight swelling or shrinking with mobile phases of different polarity was observed in permeability studies. Good retentions and efficient separations of polar analytes, such as neutral amides and phenols, were well achieved in hydrophilic interaction chromatography mode with only about 50% ACN content in the mobile phase. It was remarkably lower than the content of ACN (>90%) used on the hydrophilic polymethacrylate-based monoliths reported previously. Additionally, a mixed mode of hydrophilic interaction (HI) and strong cation-exchange (SCX) could be also obtained in the analysis of charged peptides, and high column efficiency up to 80,000plates/m was achieved without peak tailing. The prepared hydrophilic stationary phase might provide a potential environmental friendly separation media for polar solutes as it consumes a low volume of organic solvents. [Copyright &y& Elsevier]

Abstract: In this paper, the pressurized capillary electrochromatography (pCEC) with UV detection was utilized for the separation and determination of three structurally related estrogens, such as diethylstilbestrol (DES), hexestrol (HEX) and dienestrol (DE), which were difficult to be separated by capillary electrophoresis (CE) and HPLC due to their similarity in the structure and charge-to-mass ratios. Experiments were carried out in a commercially available pCEC instrument using a capillary column packed with 3μm octadecyl silica (ODS). Surfactant sodium dodecyl sulfate (SDS) was introduced in the mobile phase to enhance the speed of analysis. The effective factors on the retention time and separation resolution, such as the applied voltage, supplementary pressure, the pH and the concentration of the buffer solution, the concentration of SDS, and the content of acetonitrile in the mobile phase, were evaluated. Based on the investigation, 31% (v/v) acetonitrile and 69% (v/v) of 10mmol/L phosphate buffer (pH 6.5) containing 1.0mmol/L SDS at an applied voltage of −12kV and a supplementary pressure of 1000psi were found to be the optimal conditions for pCEC to separate the three estrogens. The method also had been applied to the analysis of fish muscle samples spiked with estrogens. [Copyright &y& Elsevier]

• A GC-MS/MS combining with silylation method was developed to determine 171 hydroxyl flavour additives in cigarette smoke. • Silylation in combination with GC-MS/MS has advantages in terms of high selectivity and sensitivity. • The novel use of a fused silica splitter simplified installation of backflushing system and exhibited better performance. • This method possessed good accuracy, satisfactory sensitivity and long-term robustness. • The developed method was applied to 270 practical cigarette smoke samples and meaningful results of HFAs were obtained. Flavour additives with carboxyl and hydroxyl groups (FACHs), the key ingredients in characteristic flavours, are frequently detected in cigarette smoke. They are attracting increasing attention in regulating the flavour additives used in tobacco to curb youth tobacco use and prevent the use of additives that are harmful. In this study, a highly robust, sensitive, and precise method based on silylation and GC-MS/MS with an improved backflushing system was developed for the simultaneous analysis of 171 FACHs in cigarette smoke. Silylation has been shown to have advantages in terms of high selectivity and sensitivity to chemicals with carboxyl and hydroxyl groups, especially when combined with GC-MS/MS. The extraction and silylation conditions were optimised. Dichloromethane was used as the extraction agent. BSTFA in combination with 1% TMCS and 0.2% TMSI was selected as silylating agent for high silylation efficiency, particularly for hindered analytes. The method has been validated. The limit of detection (LOD) ranged from 0.6 to 332.3 ng/mL. 91.1% out of the analytes in QC samples had precisions lower than 10% during one month run. The improved backflushing system with a fused silica splitter was shown to be crucial in the excellent long-term robustness of the method. The developed method was used to determine flavour additives in 270 practical cigarette smoke samples with reliable results. A total of 154 FACHs were identified with wide-range levels among different cigarette brands. [ABSTRACT FROM AUTHOR]

• An AP combination suitable for seven minor tobacco alkaloids analysis was first presented. • AP provides an overall improvement in ME correction for solvents and samples. • The quantitative results of samples are accurate in different experimental scenarios. • This method possessed good accuracy, precision, and long-term robustness. Tobacco alkaloids are important precursors of carcinogenic tobacco-specific nitrosamines. Therefore, accurate quantification of tobacco alkaloids is highly important. This study investigates the compensation effects of novel analyte protectants (APs) for matrix effects (MEs) to determine seven minor tobacco alkaloids (nornicotine, myosmine, anabasine, anatabine, nicotyrine, 2,3′-bipyridine, and cotinine) in mainstream cigarette smoke with high accuracy and robustness. By comparing the heights and shapes of the chromatographic peaks before and after the addition of APs to standard solutions prepared in dichloromethane and cigarette smoke solutions, the compensation effects of 12 APs and their combinations on the MEs of seven minor tobacco alkaloids were evaluated, and the best combination of 2-pyridylethylamine (2 mg/mL)+1,2-decanediol (1 mg/mL) was identified. This AP combination could effectively improve the shapes and increase the heights (by 7–371%) of chromatographic peaks for standard solutions prepared in dichloromethane and cigarette smoke solutions. Before the addition of this AP combination, the slope ratios of the calibration curves for two types of standard solutions of the seven target chemicals were 71.4–159.8%, while they were 87.4–105.6% after the addition, indicating that this AP combination reduced the matrix difference between pure solvent and cigarette smoke solution. After adding the AP combination, the standard curves of solutions prepared in dichloromethane showed good linearity (r 2 ≥ 0.999), the spiked recoveries were between 80.9% and 119.6%, and the inter- and intraday precisions were between 1.5–9.5% and 3.1–8.5%, respectively. Three commercial cigarette samples and one mixed standard solution were also tested under four different instrument working conditions to verify the long-term accuracy and ruggedness of the approach in routine real-world analysis of the method. The results showed that the RSD values were higher (3.5–25.4%) without the AP combination than that (<6.7%) with the AP combination. Because of its high accuracy, precision, and robustness, this method has good practical prospects. [ABSTRACT FROM AUTHOR]

Magnetic carbon composite (Fe 3 O 4 @C) was synthesized and applied as a reversed-dispersive solid-phase extraction sorbent for the simultaneous analysis of 40 pesticide residues in tobacco by ultrahigh-performance liquid chromatography coupled to quadrupole time-of-fight mass spectrometry. Compared to the traditional QuEChERS method, the optimized Fe 3 O 4 @C simplified clean-up process and exhibited better clean-up capability than conventional sorbents. The pesticides were qualitatively identified by accurate mass of protonated molecules, fragment ions, isotopic peak clusters, and retention time, and quantitatively determined by matrix-matched external standard method. Good linearity of the proposed method was obtained with R value greater than 0.997 for all target pesticides at concentration levels of 2–200 µg/L. The limit of detection ranged from 0.14 to 2.67 µg/kg. The recoveries and relative standard deviations of all target pesticides at three spiked concentrations of 20, 50 and 200 µg/kg were in the ranges of 80.8%–113.3% and 0.6%–16.3%, respectively. Compared with the reported methods for the analysis of multiple pesticide residues in tobacco, the proposed method has the advantages of simple to operate, high clean-up ability and less time-consuming in clean-up process. [ABSTRACT FROM AUTHOR]

Abstract: A novel electroneutral and polar silica-based hybrid monolith was developed by an in situ copolymerization of 2-hydroxyethylmethacrylate (HEMA) and polyhedral oligomeric silsesquioxane methacryl substituted (POSS-MA), and successfully employed for hydrophilic interaction capillary electrochromatography (HI-CEC). A good mechanical stability of the prepared monolith was gained with the permeability decreasing from 6.52×10−14 m2 to 4.61×10−14 m2 when mobile phase changed from ACN to water. A significant cathodal EOF was obtained through attracting ions from the mobile phase despite the fact that it was devoid of ionizable functional groups on the surface of stationary phases, and a typical HI-CEC mechanism was achieved. The morphologies of the hybrid silica-based monolithic matrixes were observed, and the performance of this silica-based hybrid monolith was also investigated. Satisfactory column performances were carried out for both the neutral and charged analytes with HI-CEC. The analytes including uncharged amides and phenols, charged nucleic acid bases and nucleosides and enkephalins, were well separated with good peak symmetry. High separation efficiencies of charged alkaloids and enkephalins could get up to 145,000plates/m and 75,000plates/m, respectively. [Copyright &y& Elsevier]