GC-MS测定水产品中氯霉素的残留量

报道了利用气相色谱-质谱联用技术分析水产品中氯霉素的残留量。试样中的氯霉素用乙酸乙酯提取,经正己烷去脂,及硅烷化试剂衍生后,用配有负化学电离源的气-质联用仪测定,选择离子的质量数为466、468、470、376。衍生物的峰面积与样品质量浓度在0.5~250μg/L范围内呈良好的线性,相关系数为0.9996。当添加水平为0.5~10.0μg/kg时,回收率为74.8%~84.8%,相对标准偏差为4.90%~8.99%。     

衍生-气相色谱法测定水产品中的游离甲醛

建立了水产品中游离甲醛残留量的衍生-气相色谱快速检测方法,对衍生剂、抗干扰剂、萃取剂、色谱条件进行了研究.用HP-5 (30 m×0.32 mm i.d.,0.25 μm)毛细管色谱柱,程序升温,γ-ECD检测器,外标法定量.甲醛的检出限为0.05 mg/kg,在0.1～20.0 mg/L范围内,其线性相关系数R2=0.9994,标准偏差为0.041,在0.5、 1.5、 5.0 mg/kg 3个添加水平下回收率为89.6%～102.6%.3个实验室间的RSD为2.7%～4.4%.     

微波消解石墨炉原子吸收光谱法测定水产品中痕量铍

采用微波制样技术,用石墨炉原子吸收光谱法测定水产品中痕量铍。方法的线性范围为0-10μg·L-1,检出限为0．076 ng·g-1,相对标准偏差为2．7％,回收率为97．0％。方法准确、快速、简便,并与常压消解法的结果比较,基本一致,已用于水产品中痕量铍的测定。     

Size fractionation of aquatic colloids and particles by cross-flow filtration: analysis by scanning electron and atomic force microscopy

The suitability of the combined application of environmental scanning electron microscopy (ESEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM) for the evaluation of the ability of cross-flow filtration (CFF) to perform adequate size fractionation of freshwater colloids and particles was examined. ESEM and SEM imaging provided reference images of the CFF-generated fractions and, in estimating the experimental cut-off diameter of the membrane, provided evidence that separation was not consistent with nominal pore sizes of the membranes. However, analysis of the images showed that size distribution of CFF-generated fractions and the estimated cut-off diameter of the membranes were dependent on the advantages and limitations of the two imaging techniques. With both ESEM and SEM, best estimates of size cut-offs were lower than the nominal pore size of the membrane in the case of 0.45 μm membranes, but roughly accurate in the case of 0.1 μm pore size membranes. The results also suggested that the effectiveness of CFF may benefit from a pre-separation step using a minimally perturbing technique such as split thin-flow fractionation. AFM demonstrated the presence of colloids smaller than 50 nm in all fractions including the retentates, showing that CFF fractionation is not fully quantitative and not based on size alone. The results indicate that previous studies investigating trace element partitioning using CFF may need re-evaluation as the importance of particles and large colloids may be over-estimated.     

A study of the catalytic behavior of phosphotungstic acid-modified Janus particles in a heterogeneous oil/water pickering emulsion system

An emulsion interface materialization method was used to obtain amphiphilic silica Janus nanoparticles. Reducing the photosynthesis of aquatic organisms after water pollution. PW₁₂O₄₀³⁻ was introduced onto Janus particles by ion exchange, and an amphiphilic particle emulsion catalyst (PWO-J) was prepared. Hydrogen peroxide was used as the oxygen source, and the amphiphilicty of the catalyst was used to assemble the catalyst at the Pickering emulsion interface. The PWO-J catalyst was found to exhibit very high catalytic activity toward the oxidation of oleic acid in water-in-oil systems. The results showed that PWO-J catalysis of oxidation had similar results as CTAB and phosphotungstic acid (control system) under the same conditions. The azelaic acid recovery rate was 86.7%, and PWO-J could be reused 4 times. A reaction mechanism was proposed, and the constructed model was used to calculate a reaction rate constant of 15.32 × 10⁻⁵L•mol⁻¹•s⁻¹ for the PWO-J system. The PWO-J system had a lower activation energy than the control system, showing that the catalytic oxidation of oleic acid into azelaic acid was more likely to occur in the PWO-J system.     

Liquid chromatography methodologies for the determination of steroid hormones in aquatic environmental systems

Steroid hormones are a diverse group of natural and synthetic compounds. Their wide use in human and veterinary medicine results in their continual introduction into the environment. In recent years, environmental concern over steroids that act as endocrine disruptors has increased because of their adverse effects on organisms or their progeny. Moreover, as these compounds are not totally removed from sewage in wastewater treatment plants, they can reach the aquatic environment and persist due to their physicochemical characteristics.For this reason, a major trend in analytical chemistry is the development of rapid and efficient procedures for the extraction, determination and quantification of steroid hormones in environmental samples. Over the past few decades, the significant expansion of liquid chromatography technology utilizing mass spectrometry detection has led to applications with increased selectivity and sensitivity. Optimized extraction and microextraction techniques combined to these liquid chromatography techniques have lowered detection and quantification limits to the ng L⁻¹–μg L⁻¹ range, which is the concentration of steroid hormones in liquid, solid and biota samples.In this paper, the state-of-the-art techniques for the analysis of steroid hormones focused mainly in based liquid chromatography methods in liquid and aquatic solid and biota samples are reviewed. Handling, storage, extraction and detection methodologies are reviewed and compared for all families of steroid hormones.     

Optimization of Square Wave Voltammetry (SWV) Parameters by Design of Experiment (DoE) Methodologies for the Determination of Mifepristone at Glassy Carbon Electrode (GCE)

In the present study, an electroanalytical method that permits the optimization of factors affecting SWV for sensitive detection of mifepristone at glassy carbon electrode (GCE) using response surface methodology (RSM) with desirability function (DF) is presented. Factors selected for optimization after screening using full factorial design were frequency (X₁), amplitude (X₂), and pH (X₃). The central composite design as a response surface methodology with desirability function (DF) was applied for obtaining the optimum level. The optimum conditions were obtained as follows: Frequency (X₁=50 Hz), amplitude (X₂=33.4 mV), and pH (X₃=9.4), with an overall desirability function of 0.97. Subsequently, confirmatory experiments were performed in triplicates to validate the optimum conditions. The results obtained were satisfactory and agreed well with less only 11.9 % deviation from the values predicted by the model. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.54 and 1.80 ppm, respectively. The proposed method was applied for a quantitative determination of mifepristone in spiked tap water samples. The recovery tests showed that the detection of mifepristone at GC could be evaluated on environmental samples.     

蛋白质对测定水产品中氯苯类化合物的影响及消除

提出了气相色谱-质谱法测定水产品中1,3-二氯苯,1,2-二氯苯,1,2,4-三氯苯等3种氯苯类化合物含量的方法。采用荧光猝灭法研究了氯苯类化合物与蛋白质之间的结合作用,结果表明氯苯类化合物与鱼血清白蛋白之间存在较强的结合作用。水产品样品以丙酮-磷酸氢二钾-水双水相体系进行前处理。在气相色谱分离中用DB-WAX毛细管色谱柱为固定相,在质谱分析中采用选择离子监测模式。3种氯苯类化合物的质量浓度均在0.5~5.0mg·L-1范围内与其峰面积呈线性关系。以空白样品为基体进行加标回收试验,所得回收率在77.0%~116%之间,相对标准偏差(n=6)在2.6%~7.1%之间。     

Wide-scope screening of polar contaminants of concern in water: A critical review of liquid chromatography-high resolution mass spectrometry-based strategies

The number of chemicals with potential to reach the environment is still largely unknown, which poses great challenges for both environmental scientists and analytical chemists. Liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) is currently the instrumentation of choice for identification of wide-scope polar chemicals of concern (CECs) in water. This review critically evaluates all steps involved in screening for polar CECs in water, including sampling and extraction, analysis by LC-HRMS, data (pre-)treatment, evaluation and reporting. Passive samplers and direct injection, in combination with LC-HRMS, provide new opportunities compared with conventional grab water sampling, as do instrumental advances such as ion-mobility spectrometry coupled to HRMS (IM-HRMS). In this paper, we argue that target, suspect and non-target screening should not be viewed as three separate principles, but rather as conceptual approaches to general data treatment strategies that can be linked together. Due to the large amount of data generated, smart prioritisation strategies are needed, in particular for non-target screening, to reduce complexity and focus on data of high interest. We critically evaluate existing strategies and consider that each prioritisation step will result in data loss (as any other step in a screening study), requiring compromises depending on the research question to be tackled. Many different data treatment strategies have been developed in recent years, but structure elucidation remains a challenging and time-consuming task. We discuss current and potential future trends, e.g. effect-based methods that can be used as future prioritisation tools, technological advances like IM-HRMS and improved software solutions that can enable new data treatment strategies.     

The epipharyngeal sensilla of the damselfly Ischnura elegans (Odonata,Coenagrionidae)

The knowledge on Odonata adult mouthparts sensilla is scanty and, notwithstanding the epipharynx in the labrum is considered an organ of taste, no ultrastructural investigation has been performed so far on this structure in Odonata. The labrum of the adult of the damselfly Ischnura elegans (Odonata, Coenagrionidae) shows on its ventral side the epipharynx with sensilla represented by articulated hairs and by small pegs located at the apex of slightly raised domes. Under scanning and transmission electron microscope, the articulated hairs, with a well developed socket and tubular body, have the typical structure of bristles, the most common type of insect mechanoreceptors, usually responding to direct touch; the pegs, showing an apical pore together with a variable number of sensory neurons (from two to five), the outer dendritic segments of which show a dendrite sheath stopping along their length, have features typical of contact chemoreceptors.