Multi-Residue Analysis by Liquid Chromatography-Mass Spectrometry Coupling. Application to Drinking and River Waters

Abstract

The coupling between liquid chromatography and mass spectrometry with an APCI or ESI interface (in positive or negative mode) is used here for multi-residue analyses in natural waters, covering basic and neutral pesticides as well as acid pesticides. The methods developed are applied to drinking and, river waters after the samples are concentrated by liquid-liquid extraction or solid phase extraction on C18 cartridges. Comparisons are made between UV detection and mass spectrometry and between two chromatographic methods for acid substances. The quantitation limits range from 0.01 to 0.1 μg/l according to the substance.     

无溶剂合成1,3,5-三芳基-2-芳酰基环己醇衍生物和晶体结构

在NaOH存在下室温研磨查尔酮与丙二腈,可以有效地得到1,3,5-三芳基-2-芳酰基环己醇衍生物,本合成方法反应时间短、操作简单、产率高,符合绿色化学特点.产物结构经过红外、核磁、元素分析和高分辨质谱确证,并对3b做了单晶衍射测定.     

常压高频放电等离子体炬改进制备CO2/CH4重整用Ni/MgO催化剂

比较了常规法、等离子体炬法和等离子体炬辅助焙烧法制得的Ni/MgO催化剂上CO2/CH4重整反应性能差异,并利用X射线衍射、透射电镜、X射线光电子能谱和CO2程序升温表面反应等技术对反应前后催化剂进行了表征,结果表明,采用等离子体炬辅助焙烧法制备的催化剂上Ni晶粒粒径小,分散度较高,低温活性和抗积炭性能较高;在常压,7...     

Daytime Reactions of 1,8‐Cineole in the Troposphere

Relative rate coefficients for the gas‐phase reaction of chlorine atoms (Cl) and hydroxyl radicals (OH) with 1,8‐cineole were determined by Fourier‐transform infrared (FTIR) spectroscopy between 285 and 313 K at atmospheric pressure. The temperature dependence of both reactions shows simple Arrhenius behaviour which can be represented by the following expressions (in units of cm³ molecule^?1s^?1): k(1,8‐cineole+OH)=(6.28±6.53)×10^?8exp[(?2549.3±155.7)/T] and k(1,8‐cineole+Cl)=(1.35±1.07)×10^?10exp[(?151.6±237.7)/T]. Major products of the titled reactions were identified by solid‐phase microextraction (SPME) coupled to a GC‐MS. Additionally, the first step of the reaction was theoretically studied by ab initio calculations and a reaction mechanism is proposed.     

Hydrolysis of HNSO2: A potential route for atmospheric production of H2SO4 and NH3

The hydrolysis of sulfonylamine (HNSO₂) results in the formation of sulfuric acid along with ammonia, and is of significant interest due to their negative impact on environment and life on Earth. The formation of H₂SO₄ through the reaction of HNSO₂ with (H₂O)_2-4 has been studied using high level electronic structure calculations. This hydrolysis reaction is a step-wise process, in the first step a H-atom from H₂O is transferred to the N-atom of HNSO₂ which results in the formation of NH₂, and in the next step, H₂SO₄, NH₃ and water molecule(s) are formed. The results show that the energy barrier associated with the formation of intermediates and product complexes is reduced by 7 to 10 kcal/mol when the number of water molecules is increased from 2 to 4. The rate constant was calculated using canonical variational transition state theory with small curvature tunneling correction over the temperature range of 200 to 1000 K. At 298 K, the calculated rate constant for the formation of intermediate in the first step is 2.24 × 10⁻¹⁶, 1.03 × 10⁻¹², and 2.10 × 10⁻¹¹ cm³ mol⁻¹ s⁻¹, respectively, for the reaction with water dimer, trimer and tetramer. The calculated enthalpy and free energy show that the reaction corresponding to the formation of H₂SO₄ is highly exothermic and exoergic in nature.     

铈和镧对Q345B钢在海洋大气中腐蚀行为的影响

通过周浸实验对普通Q345B钢和含有微量稀土铈(Ce)和镧(La)的Q345 BRE钢在模拟海洋大气腐蚀环境下,进行了耐腐蚀性能比较.利用失重和电化学方法进行两者的腐蚀速率比较,利用SEM和XRD分析了两者腐蚀形貌和锈层的特征.结果表明:加入混合稀土铈和镧的Q345B钢的腐蚀速率小于普通的Q345B钢,且腐蚀形貌也发生...     

古海洋环境演化对富钴结壳稀土元素富集的制约

为了探讨古海洋环境演化对海山富钴结壳稀土元素富集的制约,本次选取西太平洋Lamont海山具有多层结构富钻结壳L1作为研究对象,逐层取样分析研究,认为古海洋环境演化以及磷酸盐化作用对不同稀土元素的影响不同:Ce含量受海洋生产力水平的制约,与形成时古海洋生产力水平呈正相关关系,但受磷酸盐化影响并不显著;而磷酸盐化对富钻结壳中其他稀土元素影响存在明显差异:导致老壳层中稀土元素相对较少,而重稀土元素则相对增加.另外富钴结壳壳层在生成后可能仍然继续与周边海水发生稀土元素交换,导致壳层生成得越早,其重稀土元素相对于其他稀土元素越富集,而Eu则越亏损.     

中空纤维三相液相微萃取-高效液相色谱法测定水中的4种酚类化合物

建立了中空纤维液-液-液三相微萃取-高效液相色谱法测定水中4种酚类化合物的方法.实验系统地优化了影响萃取效率的因素(包括有机溶剂种类、接收相浓度、分散相pH值、加盐量、转速及萃取时间).得到的最佳萃取条件为:萃取剂为正辛醇,接收相NaOH溶液的浓度为0.09 mol/L,分散相的pH为4,萃取时间为40 min,搅拌速...     

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.