Recent advances in analytical methodologies based on mass spectrometry for the environmental analysis of halogenated organic contaminants

Halogenated organic contaminants, including legislated and potential persistent organic pollutants and their precursors, represent a major environmental concern due to their hazardous effects in humans and wildlife as well as their ability to bioaccumulate through the food chain, their high resistance to environmental degradation, and their long-range atmospheric transport potential. The monitoring of these compounds in the environment at ultra-trace concentration levels requires highly selective and sensitive analytical methodologies. The lack of reference step-by-step methods led to a high number of reliable determinations depending on analytes, the complexity of the sample, and available instrumentation. Thus, this review article is mainly focused on the last advances in the analytical methodologies for the determination of halogenated organic contaminants. Methodologies regarding sample treatment, chromatographic separation, and mass spectrometry analysis have been reviewed to finally highlight the future perspectives for the improvement of the analytical determinations of these compounds and the throughput of environmental control laboratories in this field.     

Fluorescent determination of graphene quantum dots in water samples

This work presents a simple, fast and sensitive method for the preconcentration and quantification of graphene quantum dots (GQDs) in aqueous samples. GQDs are considered an object of analysis (analyte) not an analytical tool which is the most frequent situation in Analytical Nanoscience and Nanotechnology. This approach is based on the preconcentration of graphene quantum dots on an anion exchange sorbent by solid phase extraction and their subsequent elution prior fluorimetric analysis of the solution containing graphene quantum dots. Parameters of the extraction procedure such as sample volume, type of solvent, sample pH, sample flow rate and elution conditions were investigated in order to achieve extraction efficiency. The limits of detection and quantification were 7.5 μg L⁻¹ and 25 μg L⁻¹, respectively. The precision for 200 μg L⁻¹, expressed as %RSD, was 2.8%. Recoveries percentages between 86.9 and 103.9% were obtained for two different concentration levels. Interferences from other nanoparticles were studied and no significant changes were observed at the concentration levels tested. Consequently, the optimized procedure has great potential to be applied to the determination of graphene quantum dots at trace levels in drinking and environmental waters.     

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.     

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.     

Non‐Invasive Salivary Electrochemical Quantification of Paraquat Poisoning Using Boron Doped Diamond Electrode

The present work describes the first electrochemical method for quantifying paraquat herbicide poisoning in human saliva samples. Paraquat shows two couples of well‐defined peaks in aqueous solution using a boron doped diamond (BDD) electrode. By using square wave voltammetry (SWV) technique under optimum experimental conditions, a linear analytical curve was obtained for paraquat concentrations ranging from 0.800 to 167 µmol L^?1, with a detection limit of 70 nmol L^?1. This method was applied to quantify paraquat spikes in human saliva samples and in two different water samples (tap and river). The recovery values obtained ranged from 83.0 to 104 % and 99.1 to 105 %, respectively, which highlight the accuracy of the proposed method.