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.     

磁性复合材料在固相萃取食品中环境类雌激素的应用进展EI北大核心CSCD

环境类雌激素作为食品中一类典型的污染物,严重影响人体内分泌系统的功能与代谢。磁性固相萃取因其简洁高效、富集倍数高、适用范围广等优点,已被广泛应用于食品中环境类雌激素的富集检测。Fe_(3)O_(4)纳米粒子作为经典的磁固相萃取材料,易于形成大分子团聚物,影响其选择吸附性能,限制了磁固相萃取技术在食品中环境类雌激素的痕量分析。新兴的磁性复合材料可有效地解决上述问题,已成为磁固相萃取技术的研究热点之一。本文综述了近5年来新兴的磁性聚合物复合材料、磁性碳基复合材料和磁性金属-有机骨架复合材料在食品中环境类雌激素富集检测的应用进展。     

Preparation and characterization of fragrance by extracting the essential oils from different raw materials

The extraction is a simple process and it is widely used to extract the fragrances in fragrance industries from essential oils. There are number of compounds (i.e. flowers, oils, leaves etc.) from which we can prepare the fragrance by extracting the essential oils from them. In this work, we have prepared the fragrance from the essential oils by the liquid-liquid extraction process, where the essential oil presented as the concentrated hydrophobic liquid containing volatile aroma compounds. We used the combination of Gas chromatography and Mass spectrometry (GC/MS) characterization techniques to make our product more useful, convenient and compitative with the other fragrance available in the market. This study would be helpful to understand the preparation of the fragrance from the concentrated hydrophobic liquid type essential oils which contains volatile aroma compounds by using a significant liquid-liquid extraction process.     

Wastes from Wood Extraction Used in Composite Materials: Behavior after Accelerated Weathering

New materials were obtained by incorporating in polypropylene (PP) matrix 60% wood wastes resulting after extraction with supercritical carbon dioxide, water, and ethanol. Structural, mechanical, thermal, and rheological characterizations, as well as moisture uptake of the composites, were evaluated before and after accelerated weathering. It was found that the extraction method influenced the composite properties due to the hydrophilic-hydrophobic balance. The addition of extracted fibers results in an increase in hardness and tensile properties and a decrease of impact strength as compared to PP.     

在LiCl-KCl-ZnCl_2熔盐体系中电化学共还原提取钕

针对镧系元素钕,本文通过循环伏安、开路计时电位、方波伏安等方法研究了773 K时Nd(III)在钼电极上在LiCl-KCl-ZnCl2熔盐体系中的电化学行为及Zn-Nd合金的形成过程.结果表明:在LiCl-KCl-ZnCl2熔盐中,Nd(III)在预先沉积的Zn阴极上欠电位沉积形成三种Zn-Nd金属间化合物.基于电化学行为研究,采用恒电位电解提取Nd并用方波伏安曲线测量来检测Nd(III)离子浓度的变化,然后通过电解前后Nd(III)离子浓度变化评估了Nd的电解提取效率.实验结果表明:-1.84 V恒电位电解进行50 h后,Nd(III)离子浓度接近于零,提取效率为99.67%.在973 K时通过恒电流电解提取Nd并获得了Zn-Nd合金,通过X射线衍射(XRD)和扫描电子显微镜(SEM)附带能量散射谱(EDS)对合金的相组成和微观形貌进行了分析.XRD分析表明在Zn-Nd合金中存在Nd2Zn17,LiZn和Zn相,EDS能谱分析表明Nd在合金中的原子分数高达14.99%.     

Optimization of Adsorbent Layer Type and Developing Solvent in Coccidiostats Sample Preparation with Procedure of Solvent Front Position Extraction

Coccidiostats are drugs used against coccidiosis, a common disease among breeding animals. Their widespread application leads to the appearance of their residues in food, which is potentially harmful for human health and life. The European Union has established limits of concentrations of these drugs in premixtures and food. Nowadays, there are many methods for monitoring coccidiostats’ presence in market products, but their frequent weakness is sample preparation. Solvent Front Position Extraction is a planar chromatography-based sample preparation method that allows for effective assay of samples with coccidiostats when coupled with LC-MS/MS. The purpose of this research was to find common conditions for the effective isolation of eight coccidiostats from biological sample components with both lower and higher retention than the substances of interest. The acquired results were used for effective isolation of monensin and salinomycin from the premixture samples and allowed for their quantitative determination. The application of a semi-automatic device for the development of chromatograms positively impacted the results, confirming the effectiveness of the method for determining coccidiostats in biological samples.     

Off-line SFE-CGC-ECD analysis of 2,4-D and Dicamba residues in real sugar cane,rice and corn samples

Determination of 2,4-D (2,4-dichlorophenoxyacetic acid) and Dicamba (2-methoxy-3,6-dichlorobenzoic acid) residues in sugar cane, rice, and corn was carried out both by solid liquid extraction (SLE), as already described in the literature, and by a supercritical fluid extraction (SFE) method developed in our laboratory. The extracts were esterified and cleaned-up by passing through a Florisil column. Extracts were analyzed by high resolution gas chromatography, with electron capture detection. The tested methods presented good recoveries (above 90%); the SFE CO₂/acetone method showed better extraction efficiencies (extracted 30 % more herbicide in real samples), shorter extraction time and lower organic solvent consumption than the SLE method.     

Optimization of a New Extraction Technique for Analysis of Verbenone and cis-Verbenol in Pine Seeds

Results from a systematic study of the factors affecting extraction of cis-verbenol and verbenone from pine seeds are presented. Five extraction conditions were investigated: extraction solvent, method of extraction, extraction temperature, volume of solvent, and the ratio of the mass of sample to the amount of extraction solvent. The resulting optimized method uses magnetic-stirring-assisted extraction of pine seeds (5 g) with ethyl acetate (75 mL) for 20 min, at room temperature. RSDs were less than 5% for both compounds. GC–FID was used for quantification of cis-verbenol and verbenone in the extracts.     

萃取色谱分离稀土元素进展

评述了近年来我国学者对萃取色谱分离稀土元素各种体系的研究及其在高纯稀土分离方面的应用，并对高纯稀土制备的发展方向进行了展望。     

2-乙基己醇萃取-原子吸收光谱法测定微量镓

在７．０ｍｏｌ／Ｌ盐酸介质中,在抗坏血酸存在下,用２－乙基己醇萃取试样溶液中的酸性铬蓝Ｋ－镓的络合物,然后用３０ｇ／Ｌ的硫脲将络合物反萃取到水相中,用ＦＡＡＳ法测定镓,据此建立了萃取反萃取－ＦＡＡＳ法测定微量镓的新方法。方法线性范围为０～６０．０ｍｇ／Ｌ,灵敏度为０．２８ｍｇ／Ｌ／１％,已用于铝酸钠溶液中微量镓的测定。