In-line coupling of microextractions across polymer inclusion membranes to capillary zone electrophoresis for rapid determination of formate in blood samples

Polymer inclusion membranes (PIMs) have several important features, i.e., PIMs are dry and non-porous membranes, which can be prepared ahead of use and stored without noticeable deterioration in extraction performance. In this contribution, in-line coupling of microextractions across PIMs to a separation method for clinical purposes was demonstrated for the first time. Formate (the major metabolite in methanol poisoning) was determined in undiluted human serum and whole blood by capillary zone electrophoresis (CZE) with simultaneous capacitively coupled contactless conductivity detection (C⁴D) and UV–Vis detection. A purpose-made microextraction device with PIM was coupled to a commercial CZE instrument in order to ensure complete automation of the entire analytical procedure, i.e., of formate extraction, injection, CZE separation and quantification. PIMs for formate extractions consisted of 60% (w/w) cellulose triacetate as base polymer and 40% (w/w) Aliquat™ 336 as anion carrier. The method was characterized by good repeatability of peak areas (≤7.0%) and migration times (≤0.8%) and by good linearity of calibration curves (r² = 0.993–0.999). Limits of detection in various matrices ranged from 15 to 54 μM for C⁴D and from 200 to 635 μM for UV–Vis detection and were sufficiently low to clearly distinguish between endogenous and toxic levels of formate in healthy and methanol intoxicated individuals. In addition, PIMs proved that they may act as phase interfaces with excellent long-term stability since once prepared, they retained their extractions properties for, at least, two months of storage.     

离子液体自聚集磁性多壁碳纳米管固相萃取环境水样中的磺胺类药物

将1-己基-3-甲基咪唑六氟磷酸([C6MIM] [PF6])离子液体自聚集于磁性多壁碳纳米管(Fe3O4@MWCNTs)表面,并将其作为磁性固相吸附剂,建立了同时测定环境水样中磺胺二甲嘧啶、磺胺对甲氧嘧啶、磺胺邻二甲氧嘧啶和磺胺二甲异噁唑4种磺胺类药物的涡旋辅助磁性固相萃取-高效液相色谱法.优化条件为:将20.0 mg [C6MIM] [PF6]包覆的Fe3 O4@MWCNTs分散于200 mL水样中,涡旋萃取15 min,磁性分离获取磁性吸附剂,3.5 mL 1.0％乙酸铵-甲醇溶液洗脱,洗脱液氮吹至干,300 μL甲醇溶解后待下一步高效液相色谱/二极管阵列检测器(HPLC-PDA)分析.4种磺胺类药物在0.375 ～ 75.0 μg/L范围内与峰面积呈良好的线性关系,其相关系数为0.9985 ～0.9996,检出限(S/N=3)为0.079 ～0.099 μg/L,3个加标浓度水平的回收率为80.60％ ～99.99％,日内、日间测定的相对标准偏差分别为1.3％ ～6.9％和1.2％～2.9％(n=3).结果表明,本方法简单方便,易于操作,适用于环境水样中痕量磺胺类药物的检测.     

Liquid–liquid microextraction and spectrophotometric determination of anionic surfactants using Astra Phloxine FF

A novel and simple procedure for determination of anionic surfactants has been developed. The method is based on the reaction of sodium dodecyl sulphate (SDS) with Astra Phloxine FF reagent at pH 3–8, followed by liquid–liquid microextraction of the formed ion associate into an organic phase containing a mixture of carbon tetrachloride and dichloroethane (4:1, v/v) and subsequent UV-Vis detection at 555 nm. The calibration plot was linear in the range 0.006–0.29 mg L^?1 of SDS. The limit of detection (LOD), calculated based on 3s, is 0.002 mg L^?1. The method was applied to the determination of anionic surfactants in real wastewater samples.     

Trace analysis of Pt (IV) metal ions in roadside soil and water samples by Fe3O4/graphene/polypyrrole nanocomposite as a solid-phase extraction sorbent followed by atomic absorption spectrometry

A novel Fe₃O₄/graphene/polypyrrole nanocomposite has been successfully synthesised via a simple chemical method and applied as a new magnetic solid-phase extraction (MSPE) sorbent for the separation and pre-concentration of trace amounts of Pt (IV) in environmental samples followed by flame atomic absorption spectrometric (FAAS) detection. The nanocomposite has been characterised by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy. Seven important parameters, affecting the extraction efficiency of Pt (IV), including pH, adsorption time, desorption solvent type and concentration, desorption time, elution volume and sample volume, were investigated. Under the optimised conditions, the calibration graph was linear in the range of 50–1500 μg L^?1 (R = 0.993). The detection limit and pre-concentration factor (PF) for Pt (IV) were found to be 16 μg L^?1 and 112.5, respectively. Under the optimised solid-phase extraction (SPE) conditions, the adsorption isotherm and the adsorption capacity of the nanocomposite for Pt (IV) were studied. Pt (IV) adsorption equilibrium data were fitted well to the Langmuir isotherm and the maximum adsorption capacity of the magnetic sorbent was calculated from the Langmuir isotherm model as 416.7 mg g^?1. The precision of the method was studied as intraday and interday variations. A relative standard deviation percentage (RSD%) value less than 3.0 indicates that the method is precise. Also, the accuracy of the method was tested by the analysis of the standard reference material (NIST SRM 2556) and by recovery measurements on spiked real samples. It was also shown that the optimised method was suitable for the analysis of trace amounts of Pt (IV) in roadside soil, tap water and wastewater samples.     

Well‐Defined Palladium Nanoparticles Supported on Siliceous Mesocellular Foam as Heterogeneous Catalysts for the Oxidation of Water

Herein, we describe the use of Pd nanoparticles immobilized on an amino‐functionalized siliceous mesocellular foam for the catalytic oxidation of H₂O. The Pd nanocatalyst proved to be capable of mediating the four‐electron oxidation of H₂O to O₂, both chemically and photochemically. The Pd nanocatalyst is easy to prepare and shows high chemical stability, low leaching, and recyclability. Together with its promising catalytic activity, these features make the Pd nanocatalyst of potential interest for future sustainable solar‐fuel production.     

Surface and Structural Investigation of a MnOx Birnessite‐Type Water Oxidation Catalyst Formed under Photocatalytic Conditions

Catalytically active MnO_x species have been reported to form in situ from various Mn‐complexes during electrocatalytic and solution‐based water oxidation when employing cerium(IV) ammonium ammonium nitrate (CAN) oxidant as a sacrificial reagent. The full structural characterization of these oxides may be complicated by the presence of support material and lack of a pure bulk phase. For the first time, we show that highly active MnO_x catalysts form without supports in situ under photocatalytic conditions. Our most active ⁴MnO_x catalyst (～0.84 mmol O₂ mol Mn^?1 s^?1) forms from a Mn₄O₄ bearing a metal–organic framework. ⁴MnO_x is characterized by pair distribution function analysis (PDF), Raman spectroscopy, and HR‐TEM as a disordered, layered Mn‐oxide with high surface area (216 m²g^?1) and small regions of crystallinity and layer flexibility. In contrast, the ^SMnO_x formed from Mn²⁺ salt gives an amorphous species of lower surface area (80 m²g^?1) and lower activity (～0.15 mmol O₂ mol Mn^?1 s^?1). We compare these catalysts to crystalline hexagonal birnessite, which activates under the same conditions. Full deconvolution of the XPS Mn2p_3/2 core levels detects enriched Mn³⁺ and Mn²⁺ content on the surfaces, which indicates possible disproportionation/comproportionation surface equilibria.     

A single-cell encapsulation method based on a microfluidic multi-step droplet splitting system

Single cell analysis is of great significance to understand the physiological activity of organisms.Microfluidic droplet is an ideal analytical platform for single-cell analysis. We developed a microfluidic droplet splitting system integrated with a flow-focusing structure and multi-step splitting structures to form 8-line droplets and encapsulate single cells in the droplets. Droplet generation frequency reached1021 Hz with the aqueous phase flow rate of 1 m L/min and the oil phase flow rate of 15 mL /min. Relative standard deviation of the droplet size was less than 5% in a single channel, while less than 6% in all the8 channels. The system was used for encapsulating human whole blood cells. A single-cell encapsulation efficiency of 31% was obtained with the blood cell concentration of 2.5× 10~4cells/mL, and the multicellular droplet percentage was only 1.3%. The multi-step droplet splitting system for single cell encapsulation featured simple structure and high throughput.     

地质环境样品中挥发酚分析现状与进展

挥发酚被列为环境优先控制的有机污染物,已成为评价环境污染的重要指标之一。该文简述了挥发酚的化学性质及地质环境来源,概括了国内外挥发酚测定的相关标准方法,从样品预处理技术和检测技术两方面综述了近年来地质环境样品中挥发酚分析的研究现状。重点对溶剂萃取、蒸馏、固相萃取、固相微萃取和吹扫捕集等样品预处理技术,以及4-氨基安替比林分光光度法、紫外和荧光分光光度法、溴化容量法、气相色谱法、液相色谱法和酚生物传感器法等技术在地质环境样品中挥发酚分析上的应用进行了较为全面的总结,并对其未来的发展趋势进行了展望,为进一步研究挥发酚的分析技术及其环境应用提供参考。     

粉末压片—X射线荧光光谱法测定土壤中的铜铅锌砷锑钴铬镍等重金属元素

采用粉末压片法制样,使用ZSX PrimusⅡ型X射线荧光光谱仪,对土壤样品中与生命健康和环境污染有直接影响的重金属元素Cu、Pb、Zn、As、Sb、Co、Cr、Ni进行同时测定.选用土壤国家标准物质、以国家标准物质为基体自制校准物质绘制标准曲线,解决了相关标准不足的问题,拓宽了元素测定范围(10~20 000μg/g),重点探讨了As、Sb的测量条件.虽然As、Sb的检出限和准确测定下限较高,但对于土壤质量的评价有重要的参考意义.方法快速、简便、准确.     

极谱法测定地质样品中锡的方法改进

过氧化钠熔融分解样品,热水浸提,试样经铍盐做共沉淀剂,用乙二胺四乙酸(EDTA)消除钙、镁等的影响,在盐酸-氯化铵底液中,用极谱法对锡进行测定,改进并简化了国标方法.对极谱法测定地质样品中锡从熔矿方式、测试温度以及干扰元素的影响及消除等方面进行探讨,并对仪器的工作条件进行优化.锡的方法检出限为10.0μg/g.方法经标准物质验证,测定值与标准值相吻合,并进行不同仪器和方法的对比实验,结果一致,准确度高.方法精密度(RSD,n=12)低于2%.方法效率高、测定结果准确可靠,已应用于大量地质样品的分析中.