超高效液相色谱-串联质谱法同时测定水产品中加替沙星、莫西沙星和左氧氟沙星

提出了同时测定水产品中加替沙星、莫西沙星和左氧氟沙星的超高效液相色谱-串联质谱分析方法。样品经乙腈提取、正己烷除脂浓缩后用Supelclean LC-SCX固相萃取柱富集,用氨水甲醇(25+75)溶液洗脱。洗脱液氮气吹干,用乙腈-水(10+90)溶液溶解定容至2.0mL,取10μL进行分离测定。以不同体积比的乙腈与5mmol·L~(-1)乙酸铵的混合溶液为流动相作梯度淋洗,经ACQUITY UPLC BEH C_(18)色谱柱分离,采用电喷雾正离子源及多反应监测模式测定。对3种化合物的质谱裂解规律进行了研究,3种化合物的质量分数在1 00μg·kg~(-1)以内呈线性,检出限(3S/N)在3.7～4.8μg·kg~(-1)之间;以3种水产品样品为基体,在3个标准加入水平下进行回收率和精密度试验,加标回收率在70.5%～83.7%之间,相对标准偏差(n=6)均不大于13%。     

气相色谱法测定水生植物中的阿特拉津残留

确立了一套检测水生植物中阿特拉津残留量的方法.样品经石油醚-二氯甲烷混合液振荡萃取,经硅镁吸附剂层析柱净化后,采用气相色谱-电子捕获检测器检测水生植物中阿特拉津的残留量.该方法在0.062～1.0mg/L范围内峰面积与阿特拉津浓度的线性关系良好(r~2=0.9993).在0.5mg/L、1.0mg/L、1.5mg/L ...     

Development of solid-phase microextraction to study dissolved organic matter—Polycyclic aromatic hydrocarbon interactions in aquatic environment

Solid-phase microextraction coupled with gas chromatography and mass spectrometry (SPME–GC–MS) was developed for the study of interactions between polycyclic aromatic hydrocarbons (PAHs) and dissolved organic matter (DOM). After the determination of the best conditions of extraction, the tool was applied to spiked water to calculate the dissolved organic carbon water distribution coefficient (K_DOC) in presence of different mixtures of PAHs and Aldrich humic acid. The use of deuterated naphthalene as internal standard for freely dissolved PAH quantification was shown to provide more accuracy than regular external calibration. For the first time, K_DOC values of 18 PAHs were calculated using data from SPME–GC–MS and fluorescence quenching; they were in agreement with the results of previous studies. Competition between PAHs, deuterated PAHs and DOM was demonstrated, pointing out the non-linearity of PAH–DOM interactions and the stronger interactions of light molecular weight PAHs (higher K_DOC values) in absence of high molecular weight PAHs.     

Characterisation and quantification of organic phosphorus and organic nitrogen components in aquatic systems: a review

This review provides a critical assessment of knowledge regarding the determination of organic phosphorus (OP) and organic nitrogen (ON) in aquatic systems, with an emphasis on biogeochemical considerations and analytical challenges. A general background on organic phosphorus and organic nitrogen precedes a discussion of sample collection, extraction, treatment/conditioning and preconcentration of organic phosphorus/nitrogen from sediments, including suspended particulate matter, and waters, including sediment porewaters. This is followed by sections on the determination of organic phosphorus/nitrogen components. Key techniques covered for organic phosphorus components are molecular spectrometry, atomic spectrometry and enzymatic methods. For nitrogen the focus is on the measurement of total organic nitrogen concentrations by carbon hydrogen nitrogen analysis and high temperature combustion, and organic nitrogen components by gas chromatography, high-performance liquid chromatography, gel electrophoresis, mass spectrometry, nuclear magnetic resonance spectrometry, X-ray techniques and enzymatic methods. Finally future trends and needs are discussed and recommendations made.     

An Iron-Catalyzed Protein Desulfurization Method Reminiscent of Aquatic Chemistry

One pillar of protein chemical synthesis based on the application of ligation chemistries to cysteine is the group of reactions enabling the selective desulfurization of cysteine residues into alanines. Modern desulfurization reactions use a phosphine as a sink for sulfur under activation conditions involving the generation of sulfur-centered radicals. Here we show that cysteine desulfurization by a phosphine can be effected efficiently by micromolar concentrations of iron under aerobic conditions in hydrogen carbonate buffer, that is using conditions that are reminiscent of iron-catalyzed oxidation phenomena occurring in natural waters. Therefore, our work shows that chemical processes taking place in aquatic systems can be adapted to a chemical reactor for triggering a complex chemoselective transformation at the protein level, while minimizing the resort to harmful chemicals.     

水产中多种酞酸酯气-质联用分析研究

将气相色谱-电子轰击离子源-质量法(GC-EI-MS)应用于水产中多种酞酸酯的分析,其前处理方法采用超声提取-柱层析净化预分离。该方法具有较大的线性范围(20.0~800μg/kg,相关系数大于0.9995),较好的精密度(RSD≤14%),较低的检出限(LODDMP=0.711μg/kg;LODDEHP=5.67μg/kg),加标回收率在63.7%~116%之间。应用于文蛤、海带和章鱼样品分析,均检测出DBP和DEHP,在海带和章鱼中还分别检测出少量的DMP与DEP。     

Evaluation of solid-phase microextraction conditions for the determination of polycyclic aromatic hydrocarbons in aquatic species using gas chromatography

This paper describes a headspace solid-phase microextraction (HS-SPME) procedure coupled to gas chromatography with mass spectrometric detection (GC–MS) for the determination of eight PAHs in aquatic species. The influence of various parameters on the PAH extraction efficiency was carefully examined. At 75 °C and for an extraction time of 60 min, a polydimethylsiloxane–divinylbenzene (PDMS/DVB) fiber coating was found to be most suitable. Under the optimized conditions, detection limits ranged from 8 to 450 pg g⁻¹, depending on the compound and the sample matrix. The repeatability varied between 7 and 15% (RSD). Accuracy was tested using the NIST SRM 1974b reference material. The method was successfully applied to different samples, and the studied PAHs were detected in several of the samples. Figure Headspace SPME sampling followed by GC–MS facilitates routine monitoring of PAHs in aquatic species     

Validation and application of an analytical method for monomethylmercury quantification in aquatic plant tissues

An analytical methodology for monomethylmercury (MMHg) determination in aquatic plant tissues with low detection limit (346 pg g⁻¹) is proposed. It consists of acid digestion (HBr/CuSO₄), cleanup step with a Na₂S solution, pre-concentration procedure using a dithizone solution in toluene and quantification by GC–ECD. The performance of the methodology has been tested by determining the MMHg concentrations in the certified reference material Fucus Sea Plant Homogenate—IAEA-140/TM (CRM) and in leaves, stems and roots of the salt marsh plants Sarcocornia fruticosa and Halimione portulacoides. The results obtained for CRM were not statistically different ( = 0.056) from the certified value and repeatability was lower than 2.5% for the plant samples analyzed. This coefficient of variation was similar to those obtained in the externally quality control using within-batch and between-batch (<1.4%).     

LC-MS/MS内标法测定水产品中三聚氰胺残留量

建立了高效液相色谱-电喷雾串联质谱(LC-MS/MS)测定水产品中残留的三聚氰胺的方法.以13C,15N标记三聚氰胺为内标,样品经三氯乙酸溶液沉淀蛋白,提取目标分析物,经SCX-C18均匀混合填装的反相色谱柱分离,选择反应监测(SRM)正离子模式测定.LC-MS/MS的检测低限为10 μg/kg;在10.0～500 ng/mL时峰强度与质量浓度的线性关系良好(r>0.99).方法的平均回收率为78%～118%.