碱催化法衍生化气相色谱/质谱法分析青海湖裸鲤鱼油中的脂肪酸

用碱催化法将青海湖裸鲤鱼油甲酯化,以气相色谱/质谱法分析鱼油中的脂肪酸。青海湖裸鲤可食用部分中鱼油含量为25.13%。从鱼油中共鉴定出47种脂肪酸,包括直链、单支链、多支链饱和脂肪酸,单不饱和、多不饱和脂肪酸,环丙烷基、呋喃基脂肪酸等。不饱和脂肪酸含量为73.6%,其中多不饱和脂肪酸含量为25.4%,以C18∶2(4.9%),C18∶3(3.1%),C20∶4(1.3%),C20∶5(二十碳五烯酸（EPA）, 9.4%)和C22∶6(二十二碳六烯酸（DHA）, 6.7%)为主。单不饱和脂肪酸含量为48.2%,主要由C16∶1(20.3%),C18∶1(25.9%)构成。饱和脂肪酸含量为25.7%,主要有C14∶0(3.4%),C16∶0 (19.4%)和C18∶0(1.1%)。青海湖裸鲤鱼油中还存在不常见的环丙烷基和呋喃基脂肪酸及多种奇数碳链和支链脂肪酸。因此,青海湖裸鲤是功能性脂肪酸的重要膳食来源。     

邻氨基苯酚化学修饰试剂用于气相色谱/质谱分析花粉脂肪酸

采用邻氨基苯酚作为脂肪酸的化学修饰试剂,将羧基修改为含氮杂环,使在EI源中避免链烯基中碳碳双键的移动。以气相色谱／EI质谱分析花粉脂肪酸,解析脂肪酸邻氨基苯酚化学修饰产物的EI质谱图;讨论了烯酸中碳碳双键的定位规则;鉴定出巨日花粉12种脂肪酸,由C12-C24脂肪酸组成,不饱和脂肪酸的含量占73．94％,其中多不饱和脂肪酸含量占47．61％,多不饱和脂肪酸与饱和脂肪酸之比达1.85,还检出了在其他花粉中极为少见的人体必需脂肪酸15-二十四烯酸(神经酸)。     

不粘锅涂层中全氟辛酸及其盐的快速溶剂萃取-气相色谱-质谱法测定

建立了不粘锅涂层中全氟辛酸(PFOA)及其盐残留量的气相色谱-负离子化学电离质谱（GC/NCI-MS）测定方法。样品经快速溶剂萃取仪提取及衍生化处理后进行GC/NCI-MS测定。PFOA的定量检测限为5 μg/kg;4个添加水平的平均回收率为90.9%~96.2%,相对标准偏差为1.37%~6.37%。该方法提取时间短,提取效率高,衍生化步骤简单,杂质干扰小,灵敏度高,适用性强。     

顶空固相微萃取-气相色谱/质谱法分析鉴定畜禽粪便中的挥发性有机化合物

采用顶空固相微萃取(HS-SPME)-气相色谱/质谱法(GC/MS)测定了牛粪、猪粪以及鸡粪中的挥发性有机化合物(VOCs)。在优化HS-SPME条件的基础上,通过GC/MS分析,从牛粪中分离鉴定出44种VOCs,从猪粪中分离鉴定出40种VOCs,从鸡粪中分离鉴定出41种VOCs。HS-SPME-GC/MS具有简单、快速、无需有机溶剂等特点,适合于畜禽粪便中挥发性有机化合物的分析与鉴定。同时,该研究揭示了畜禽养殖场臭味物质的来源,为治理其环境污染提供了科学依据。     

Liquid chromatography/tandem mass spectrometric method for the simultaneous determination of tobacco-specific nitrosamine NNK and its five metabolites

A sensitive and robust high-performance liquid chromatography-electrospray ionization tandem mass spectrometry method to analyze 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and its five metabolites in one passage was developed and validated. The method achieved excellent reproducibility and accuracy. Linearity was observed for all six compounds (R² = 0.999) with detection limits (S/N ≥ 3) ranging from 0.2 to 2.4 pg on column and 0.01-0.12 ng ml⁻¹ in samples injected. Average intra-day and inter-day variations (% R.S.D.) were 1.2 and 3.5%, respectively. A sample preparation method involving C8 and C18 solid phase extraction provided satisfactory recovery of the analytes in mouse urine. Each NNK metabolite was identified by its chromatographic retention time and specific fragmentation pattern. Since the carcinogenicity of NNK is related to its metabolism, the method described in this report should facilitate toxicological investigations into the carcinogenesis due to NNK exposure in the environment.     

Liquid chromatography with diode array detection and multivariate curve resolution for the selective and sensitive quantification of estrogens in natural waters

Following the green analytical chemistry principles, an efficient strategy involving second-order data provided by liquid chromatography (LC) with diode array detection (DAD) was applied for the simultaneous determination of estriol, 17β-estradiol, 17α-ethinylestradiol and estrone in natural water samples. After a simple pre-concentration step, LC–DAD matrix data were rapidly obtained (in less than 5 min) with a chromatographic system operating isocratically. Applying a second-order calibration algorithm based on multivariate curve resolution with alternating least-squares (MCR-ALS), successful resolution was achieved in the presence of sample constituents that strongly coelute with the analytes. The flexibility of this multivariate model allowed the quantification of the four estrogens in tap, mineral, underground and river water samples. Limits of detection in the range between 3 and 13 ng L⁻¹, and relative prediction errors from 2 to 11% were achieved.     

Lipid analysis by thin-layer chromatography--a review of the current state

High-performance thin-layer chromatography (HPTLC) is a widely used, fast and relatively inexpensive method of separating complex mixtures. It is particularly useful for smaller, apolar compounds and offers some advantages over HPLC. This review gives an overview about the special features as well as the problems that have to be considered upon the HPTLC analysis of lipids. The term "lipids" is used here in a broad sense and comprises fatty acids and their derivatives as well as substances related biosynthetically or functionally to these compounds. After a short introduction regarding the stationary phases and the methods how lipids can be visualized on an HPTLC plate, the individual lipid classes will be discussed and the most suitable solvent systems for their separation indicated. The focus will be on lipids that are most abundant in biological systems, i.e. cholesterol and its derivates, glycerides, sphingo- and glycolipids as well as phospholipids. Finally, a nowadays very important topic, the combination between HPTLC and mass spectrometric (MS) detection methods will be discussed. It will be shown that this is a very powerful method to investigate the identities of the HPTLC spots in more detail than by the use of common staining methods. Future aspects of HPTLC in the lipid field will be also discussed.     

Combining chromatography and chemometrics for the characterization and authentication of fats and oils from triacylglycerol compositional data—A review

The characterization and authentication of fats and oils is a subject of great importance for market and health aspects. Identification and quantification of triacylglycerols in fats and oils can be excellent tools for detecting changes in their composition due to the mixtures of these products. Most of the triacylglycerol species present in either fats or oils could be analyzed and identified by chromatographic methods. However, the natural variability of these samples and the possible presence of adulterants require the application of chemometric pattern recognition methods to facilitate the interpretation of the obtained data. In view of the growing interest in this topic, this paper reviews the literature of the application of exploratory and unsupervised/supervised chemometric methods on chromatographic data, using triacylglycerol composition for the characterization and authentication of several foodstuffs such as olive oil, vegetable oils, animal fats, fish oils, milk and dairy products, cocoa and coffee.     

The potential of mass spectrometry to study iron-containing proteins used in clinical diagnosis

Many proteins contain iron as metal ion either within their own structures or bound to their active sites. These iron-containing proteins are involved in numerous biological processes and some of them serve as biomarkers of clinical pathologies, not only related to iron homeostasis but also to other physiological disorders. Thus, a variety of analytical strategies have been developed over the last years in order to conduct studies on Fe-containing proteins. Among them, mass spectrometric (MS) methods still remain as preferred tools since they provide the capabilities of structure elucidation together with quantitative possibilities. Therefore, in this work we have tried to summarize the most recent applications of elemental and molecular mass spectrometric-based methods for the characterization (mostly qualitative but quantitative in some cases) of the high abundant Fe-containing proteins used for clinical diagnosis.     

Room temperature phosphorescence in the liquid state as a tool in analytical chemistry

A wide-ranging overview of room temperature phosphorescence in the liquid state (RTPL¹) is presented, with a focus on recent developments. RTPL techniques like micelle-stabilized (MS)-RTP, cyclodextrin-induced (CD)-RTP, and heavy atom-induced (HAI)-RTP are discussed. These techniques are mainly applied in the stand-alone format, but coupling with some separation techniques appears to be feasible. Applications of direct, sensitized and quenched phosphorescence are also discussed. As regards sensitized and quenched RTP, emphasis is on the coupling with liquid chromatography (LC) and capillary electrophoresis (CE), but stand-alone applications are also reported. Further, the application of RTPL in immunoassays and in RTP optosensing—the optical sensing of analytes based on RTP—is reviewed. Next to the application of RTPL in quantitative analysis, its use for the structural probing of protein conformations and for time-resolved microscopy of labelled biomolecules is discussed. Finally, an overview is presented of the various analytical techniques which are based on the closely related phenomenon of long-lived lanthanide luminescence. The paper closes with a short evaluation of the state-of-the-art in RTP and a discussion on future perspectives.     

Production of monoclonal antibodies against hop-derived (Humulus lupulus L.) prenylflavonoids and the development of immunoassays

Monoclonal antibodies against the hop-derived prenylated chalcone xanthohumol (X) and the prenylated flavonoids isoxanthohumol (IX) and 8-prenylnaringenin (8-PN) were developed. Carboxylic acid haptens of X, IX and 8-PN were synthesized by linking a spacer to their C4′-OH group followed by subsequent coupling to bovine serum albumin (BSA) to form conjugates that were employed as immunogens in BALB/c mice to raise antibodies. The monoclonal antibodies that were secreted from the established hybridoma cell lines proved, in cross-reactivity studies, to possess highly specific binding capacities in an optimized competitive indirect ELISA. The immunoassays make use of immunogen-coated microtiterplates and a peroxidase-labeled anti-mouse IgG₁ secondary antibody with ABTS as a chromogenic substrate. For X the IC₅₀ value derived from the standard curve was 62.91 ng mL⁻¹, and for both IX and 8-PN 37.15 ng mL⁻¹. The assay was validated for the quantitative analysis of X, IX and 8-PN in urine and serum. A simple sample pretreatment procedure using a diethyl ether extraction was optimized and the recoveries and matrix effects were assessed. The validity of the established assay was tested and mean inter- and intra-assay variations in urine were 2.32% and 1.91%, respectively for X, 6.24% and 2.39%, respectively for IX and 7.18% and 0.74%, respectively for 8-PN. In serum, the mean inter- and intra-assay variations were 8.90% and 1.37%, respectively for X, 6.13% and 1.57%, respectively for IX and 6.13% and 2.43%, respectively for 8-PN. Furthermore, the method demonstrated excellent accuracy and significant correlation with measurements by an established and validated HPLC-MS method.     

Pesticides in water and the performance of the liquid-phase microextraction based techniques. A review

The control of pesticides in surface, drinking and groundwater is nowadays a real necessity. In the European Community, their concentration must comply with the established parametric and environmental quality standards (EQSs). Regarding the new legislation, this article updates the information concerning the monitoring of pesticides and the technical specifications for their measurement in water samples where ultra-sensitive analytical methods are required. For some compounds, like pesticides, there is still a need to improve the performance of the existing methods. High sensitive techniques like gas chromatography tandem mass spectrometry (GC–MS/MS) and liquid chromatography coupled with mass spectrometry (LC–MS) have been developed. However, for most of the substances present at trace and ultra-trace levels the extraction and preconcentration steps are so far essential for their detection. Advances at a micro scale have been made and different types of microextractions are being developed. Liquid-phase microextraction (LPME) is an example. The study of this technique has increased in the last years and some innovations have been recently reported for pesticides water analysis. This article reviews the new developed LPME-based techniques and compares its performance with the analytical specifications established for pesticides water monitoring. The results show that LPME-based techniques can be a promising tool to improve the nowadays performance of methods used in pesticides water control.     

Application of carbon-based nanomaterials in sample preparation: A review

In this paper, a broad overview on the applications of different carbon-based nanomaterials, including nanodiamonds, fullerenes, carbon nanotubes, graphene, carbon nanofibers, carbon nanocones-disks and nanohorns, as well as their functionalized forms, in sample preparation is provided. Particular attention has been paid to graphene because many papers regarding its application in this research field are becoming available. The distinctive properties, derivatization methods and application techniques of these materials were summarized and compared. According to their research status and perspective, these nanomaterials were classified in four groups (I: graphene and carbon nanotubes; II: carbon nanofibers; III: fullerenes; and IV: nanodiamonds, carbon nanocones/disks and carbon nanohorns) and characteristics and future trends of every group were discussed.