脂质组学分析中样品前处理技术的研究进展

脂质不仅是细胞膜的主要组成部分,还参与一些生命活动如能量存储、信号传导等,在生命体中发挥着重要作用。近年来,越来越多的研究表明脂质的变化与一些重大疾病的发生发展密切相关,脂质组学研究对理解疾病的发生机制及过程具有重要意义。在脂质分析过程中,由于样品基质的干扰或被分析物浓度的限制,通常需要对样品进行前处理,以得到最佳的分析性能。该文综述了脂质组学分析中的样品前处理技术,包括脂质的提取方法（如液液萃取、固相萃取等）和针对不同类脂质的化学衍生化技术在各领域,尤其是生命分析和代谢组学中的应用,并对脂质组学分析中的样品前处理技术的发展进行了展望。     

Determination of lipid content and stability in lipid nanoparticles using ultra high-performance liquid chromatography in combination with a Corona Charged Aerosol Detector

For many years, lipid nanoparticles (LNPs) have been used as delivery vehicles for various payloads (especially various oligonucleotides and mRNA), finding numerous applications in drug and vaccine development. LNP stability and bilayer fluidity are determined by the identities and the amounts of the various lipids employed in the formulation and LNP efficacy is determined in large part by the lipid composition which usually contains a cationic lipid, a PEG-lipid conjugate, cholesterol, and a zwitterionic helper phospholipid. Analytical methods developed for LNP characterization must be able to determine not only the identity and content of each individual lipid component (i.e., the parent lipids), but also the associated impurities and degradants. In this work, we describe an efficient and sensitive reversed-phase chromatographic method with charged aerosol detection (CAD) suitable for this purpose. Sample preparation diluent and mobile phase pH conditions are critical and have been optimized for the lipids of interest. This method was validated for its linearity, accuracy, precision, and specificity for lipid analysis to support process and formulation development for new drugs and vaccines.     

Recent applications of atomic spectroscopy coupled with magnetic solid-phase extraction techniques for heavy metal determination in environmental samples: A review

Atomic spectroscopy is the most popular approach to determine the presence of heavy metals in the environment. Heavy metals are potentially toxic and have various negative effects on many living organisms, including humans. With the rapid increase in the variety of industries and human activities, large amounts of heavy metals are released into the atmosphere, water, and soil. Heavy metal analysis of environmental samples is very important for determining the exposure limits. Environmental samples are highly complex matrices, and various sample preparation techniques have been developed for the extraction of heavy metals from them, including magnetic solid-phase extraction (MSPE). The use of MSPE in heavy metal analysis has recently gained significant attention owing to a number of advantages. MSPE technique overcomes main issues such as phase separation, handling, and column packing. The use of magnetic adsorbents in sample preparation has grown over the past few years, making MSPE a promising technique for sample preparation. The objective of this review article is to provide the latest applications of MSPE coupled with atomic spectroscopy for heavy metal determination in environmental samples. In addition, new magnetic adsorbents and their analytical merits are emphasized.     

Techniques and procedures for preparation of aquatic samples for chromatographic analyses

The measurement of low levels of organic compounds in environmental samples presents the researcher with a number of possible pathways to effectively obtain and analyze samples. Numerous sampling methods, sample preparation techniques, and extraction procedures are available. A number of different approaches to sampling strategy, isolation, concentration, cleanup and fractionation will be discussed. Objectives for collecting environmental samples differ from those for many other types of samples because reliable measurements at very low levels are frequently required. Often, specific analytes need to be measured at the μg/kg and even ng/kg levels in complex matrices. Advances in analytical methodology continue to lower the levels at which reliable measurements can be made. At these levels, many factors that are of little or no concern in other analytical measurements are of critical importance in influencing the outcome and reliability of environmental analyses. Analytical measurements are used for determining the composition and the quantities of analytes in the defined system at various concentration levels. Environmental analytical measurements provide data about the transportation and transformation of an environmental contraminant and for determination of its concentration in a sample.     

Electrical field-induced extraction and separation techniques: Promising trends in analytical chemistry – A review

Sample preparation is an important issue in analytical chemistry, and is often a bottleneck in chemical analysis. So, the major incentive for the recent research has been to attain faster, simpler, less expensive, and more environmentally friendly sample preparation methods. The use of auxiliary energies, such as heat, ultrasound, and microwave, is one of the strategies that have been employed in sample preparation to reach the above purposes. Application of electrical driving force is the current state-of-the-art, which presents new possibilities for simplifying and shortening the sample preparation process as well as enhancing its selectivity. The electrical driving force has scarcely been utilized in comparison with other auxiliary energies. In this review, the different roles of electrical driving force (as a powerful auxiliary energy) in various extraction techniques, including liquid-, solid-, and membrane-based methods, have been taken into consideration. Also, the references have been made available, relevant to the developments in separation techniques and Lab-on-a-Chip (LOC) systems. All aspects of electrical driving force in extraction and separation methods are too specific to be treated in this contribution. However, the main aim of this review is to provide a brief knowledge about the different fields of analytical chemistry, with an emphasis on the latest efforts put into the electrically assisted membrane-based sample preparation systems. The advantages and disadvantages of these approaches as well as the new achievements in these areas have been discussed, which might be helpful for further progress in the future.     

A quantitative densitometric method for the rapid separation and quantitation of the major tissue and lipoprotein lipids by high-performance thin-layer chromatography. I. Sample preparation, chromatography, and densitometry

A rapid method for the separation and quantitation of the major lipids of tissues and lipoproteins by automated high-performance thin-layer chromatography is presented. Solvent systems for one-dimensional separation of neutral lipids, of cholesteryl esters, and of phospholipids are described. Separated lipids are measured following treatment with methanolic sulphuric acid containing manganese chloride and scanned in fluorescence or absorption mode. Absolute quantitation is obtained by the use of an internal standard and by references to standards for each lipid run on the same plates as samples. The method described here is particularly suitable for the rapid quantitation of small amounts of lipid (0.01-0.02 nmol per sample), for example in tissue culture studies; 100 micrograms of fibroblast or macrophage protein are sufficient for complete lipid analysis. The coefficients of variation due to the sample preparation, application to the plates and densitometry are in the range 7.2-9.1%. The method was compared with enzymatic determinations for cholesterol and gave correlation coefficients of 0.95 for total cholesterol and 0.91 for unesterified cholesterol. Phospholipid estimation was compared with large-plate thin-layer chromatography and phosphorus analysis and gave correlation coefficients of 0.90 for phosphatidylcholine and 0.89 for sphingomyelin.     

基于色谱-质谱联用的脂质分析样品前处理技术研究进展

脂质作为细胞膜和亚细胞膜的主要结构成分,在能量来源、细胞信号传导等多种生物学过程中发挥着重要作用。近年来,脂质分析受到越来越多的关注,其中色谱-质谱联用技术在脂质分析中占据主导地位。由于样品基质复杂,样品前处理有富集痕量物质和减少基质干扰的作用,成为脂质分析中的一个关键步骤。该文综述了近年来基于色谱-质谱联用技术的脂质分析中样品前处理技术的研究进展和应用,对各种样品前处理技术进行了阐述和总结。基于液相的萃取方法有液-液萃取和单一有机溶剂萃取。基于固相的萃取方法包括固相萃取和固相微萃取。场辅助萃取方法包括超临界流体萃取、加压流体萃取、微波辅助萃取和超声辅助萃取。此外,还介绍了在线联用样品前处理方法和用于活体分析的样品前处理方法。最后,对基于色谱-质谱联用的脂质分析样品前处理技术存在的问题及发展趋势进行了探讨。样品前处理技术的发展将提高脂质分析的灵敏度、选择性和分析速度。     

Determination of diffusible and total hydrogen concentration in coated and uncoated steel using melt and solid extraction techniques: Part I

It is essentially to know the bulk hydrogen concentration in various types of steel because it indicates the amount of hydrogen that can be trapped by the different alloys of steel. This information leads to more knowledge about the interactions of steel alloys with hydrogen containing environment and stability of the steel material during usage. To get this information precise analytical methods are necessary.Although the analytical methods for the determination of hydrogen in steel samples are often discussed, there are no sufficient systematic studies as far as the influence of the sample preparation on the analytical value is concerned.The influence of different sample preparation methods on the hydrogen determination in steel at parts per million levels by melting extracting methods has been investigated in this work. The hydrogen was measured by thermal conductivity and infrared detection. The flat sheet samples were zinc coated and uncoated ferritic types of steel. The zinc coating was removed by chemical (acid etching) and physical (paper scraping) methods. Dichloromethane acetone/ethanol, tetrachloromethane and alkaline steel cleaner (Ridoline C72) have been used for cleaning the surface of uncoated samples. The results of the total hydrogen content obtained by applying the different methods were evaluated.     

Lipids of the fruit of Diospyros kaki

The composition and amounts of the various groups of liposoluble compounds in the rind and flesh of persimmon fruit of the varieties Hachiya and Hyakume have been established by a combination of chromatographic and chemical methods. The identity of the qualitative composition of the lipids of the flesh and rind of the fruit and quantitative differences in the amounts of individual groups have been found. A total of 24 groups of compounds were identified, the main ones of which were monogalactosyldiglycerides, carotenoids, diacylglycerols, ceramide oligosides, digalactosyldiglycerides, phosphatidylglycerols; phosphatidylcholines, and free and glycosylated sterols. In the fatty acid composition of the lipids unsaturated fatty acids — linolenic, oleic, linoleic, and palmitoleic — predominated (>70%).     

Sample Preparation Techniques—An Important Part in Trace Element Analysis for Environmental Research and Monitoring

Abstract

For the determination of minute amounts of elements in environmental samples combined analytical procedures are frequently employed. The combination of suitable sample preparation techniques with adequate detection methods lead to powerful analytical procedures. Decomposition methods are an important part of combined procedures for the determination of trace elements in solid samples. After a short summary of the potential sources for systematic errors two new decomposition methods are described that are suitable for the ashing of organic environmental samples. In one method the organic sample is ashed in a high-frequency excited oxygen plasma. The second method is a high pressure decomposition that permits mineralization of the sample in sealed quartz vessels with nitric acid at temperatures up to 320°C.

For both methods the ratio of sample weight to decomposition reagents is comparatively high. This makes these methods in combination with adequate detection methods suitable for the determination of elements at very low concentrations.

X-ray fluorescence spectrometry combined with adequate preconcentration methods is very well suited for the simultaneous determination of trace elements. Following a critical evaluation of various preconcentration techniques the analytical characteristics of filter paper with immobilized complexing agents are described. Particular emphasis is given to filter papers with dithiocarbamates as chelating group.     

Sample preparation for the chromatographic determination of ecdysteroids using solid-phase extraction methods

The ecdysteroids are hormones widely distributed in insects and crustaceans, where they are involved in the regulation of moulting. Methods of sample preparation based on solid-phase extraction of the ecdysteroids from biological samples for subsequent chromatographic analysis are reviewed. Most methods use an initial partition of the sample (or extract) between water or aqueous methanol with a non-polar solvent to remove lipids. The aqueous portion is applied to a cartridge containing C₁₈-bonded silica gel. Removal of polar impurities is then effected, followed by recovery of the ecdysteroids from the cartridge and chromatographic analysis. Results are given for the use of phenylboronic acid (PBA) bonded to silica gel as a means of obtaining a much more specific method of extraction. The PBA phase was shown to have a high affinity for ecdysteroids containing a 20,22-cis-diol but not for compounds possessing only a 2,3-cis-diol.     

Novel contribution of chromatography in the development and analyses of metformin hydrochloride in biological and environmental samples

Globally, metformin hydrochloride (HCl) is the most commonly used antidiabetic drug and provides safe medication because of low risk of the side effects (lactic acidosis). Therefore, various researches have been established in pharmacodynamics and pharmacokinetic studies using various analytical applications such as calorimetry, spectrophotometry, and chromatography. But the chromatographic techniques are most widely used methods for the analysis of metformin HCl. This review discussed the different chromatographic methods used for the analysis of metformin HCl and its sample preparation for the isolation in different biological and environmental samples. Moreover, the mechanism for the fragmentation of ion products in LC–MS/MS is indicated for high throughput of the methods involved in the determination of metformin HCl in various sample matrices. The advancement in the chromatographic modalities provides the wide range of assays discussed herein.     

Quantitative analysis of aberrant fatty acid composition of zebrafish hepatic lipids induced by organochlorine pesticide using stable isotope-coded transmethylation and gas chromatography-mass spectrometry

Organochlorine pesticides have been extensively used worldwide for agricultural purposes. Due to their resistance to metabolism, a major public health concern has been raised. Aberrant hepatic lipid composition has been a hallmark of many liver diseases associated with exposure to various toxins and chemicals. And thus lots of efforts have been focused on the development of analytical techniques that can rapidly and quantitatively determine the changes in fatty acid composition of hepatic lipids. In this work, changes in fatty acid composition of hepatic lipids in response to DDT (dichlorodiphenyltrichloroethane) exposure were quantitatively analyzed by a gas chromatography-mass spectrometric approach based on stable isotope-coded transmethylation. It has been quantitatively demonstrated that polyunsaturated fatty acids including C20:3n3, C20:4n6, and C22:6n3 decrease in response to DDT exposure. However, saturated long chain fatty acids including C16:0, C18:0, as well as monounsaturated long chain fatty acid C18:1n9 consistently increase in a DDT-concentration-dependent manner. In particular, much higher changes in the level of hepatic C16:0 and C18:0 for male fish were observed than that for female fish. These experimental results are in accordance with qualitative histopathological analysis that revealed liver morphological alterations. The stable isotope-coded mass spectrometric approach provides a reliable means for investigating hepatotoxicity associated with fatty acid synthesis, desaturation, mitochondrial beta-oxidation, and lipid mobilization. It should be useful in elucidation of hepatotoxic mechanisms and safety assessment of environmental toxins.     

样品制备与处理的进展——无溶剂萃取技术

本文讨论了现代分析化学的重要领域之一, 样品制备及前处理技术的进展--无溶剂萃取技术。包括气相萃取、超临界流体萃取、膜萃取、固相萃取、固相微萃取等方法。简述了这些方法的原理及其应用, 探讨了样品制备与前处理技术的发展动向。     

Selective imaging of positively charged polar and nonpolar lipids by optimizing matrix solution composition

Previous studies have shown that matrix‐assisted laser desorption/ionization–imaging mass spectrometry (MALDI‐IMS) is useful for studying the distribution of various small metabolites, particularly lipids. However, in this technique, selective ionization of the target molecules is imperative, particularly when analyzing small molecules. Since the sample clean‐up procedures available for the MALDI‐IMS of small metabolites are limited, the tissue sample will contain numerous molecular species other than the target molecules. These molecules will compete for ionization resulting in severe ion suppression. Hence, it is necessary to develop and optimize a sample preparation protocol for the target molecules. In this study, through model experiments using reference compounds, we optimized the composition of the matrix solution used for positively charged lipids in terms of the concentration of the organic solvent and presence/absence of alkali metal salts. We demonstrated that a high concentration of organic solvent in the matrix solution favors the preferential detection of lipids over peptides. The presence of alkali metal salts in the matrix solution was favorable for the detection of polar lipids, while a salt‐free matrix solution was suitable for the detection of nonpolar lipids. Furthermore, potassium salts added to the matrix solution caused merging of various lipid adducts (adducts with proton, sodium, and potassium) into one single potassiated species. Using the optimized protocols, we selectively analyzed phosphatidylcholine (PC) and triacylglycerol (TG) with different fatty acid compositions in a rat kidney section. Copyright © 2009 John Wiley & Sons, Ltd.     

Determination of carbohydrates in juices by capillary electrophoresis, high-performance liquid chromatography, and matrix-assisted laser desorption/ionization-time of flight-mass spectrometry

The objective of this work was to develop a sample preparation procedure for determination of the carbohydrate profiles in commercial juice samples by three principally different analytical methods: capillary electrophoresis (CE) with indirect detection, high-performance liquid chromatography (HPLC), and matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS). The preparation and purification of juice samples prior to analysis is described. The method using Carrez reagents was found to be an efficient preparation tool for all three methods. The addition of Carrez reagents to the samples for mass analysis improved the quality of the mass spectra of oligosaccharides. The amounts of glucose, fructose, and sucrose as major carbohydrates in fruit juices measured by CE using a simple instrument are in good agreement with the HPLC values and the data declared by the producers of the juices. The results from both methods are critically evaluated and their impact for studies of authenticity is discussed. The decrease of sucrose amount during the storage of samples was explained by acid hydrolysis of this disaccharide.     

MALDI imaging mass spectrometry of lipids by adding lithium salts to the matrix solution

Mass spectrometry imaging of lipids using MALDI–TOF/TOF mass spectrometers is of growing interest for chemical mapping of organic compounds at the surface of tissue sections. Many efforts have been devoted to the best matrix choice and deposition technique. Nevertheless, the identification of lipid species desorbed from tissue sections remains problematic. It is now well-known that protonated, sodium- and potassium-cationized lipids are detected from biological samples, thus complicating the data analysis. A new sample preparation method is proposed, involving the use of lithium salts in the matrix solution in order to simplify the mass spectra with only lithium-cationized molecules instead of a mixture of various cationized species. Five different lithium salts were tested. Among them, lithium trifluoroacetate and lithium iodide merged the different lipid adducts into one single lithium-cationized species. An optimized sample preparation protocol demonstrated that the lithium trifluoroacetate salt slightly increased desorption of phosphatidylcholines. Mass spectrometry images acquired on rat brain tissue sections by adding lithium trifluoroacetate showed the best results in terms of image contrast. Moreover, more structurally relevant fragments were generated by tandem mass spectrometry when analyzing lithium-cationized species.     

Lipids of the root crop Beta vulgaris

The composition and the amounts of various groups of neutral lipids and of glyco- and phospholipids in the root cropBeta vulgaris of the varieties bordeaux and Nosovskaya ploskaya have been investigated by a combination of chromatographic and chemical methods. About 30 groups of lipid compounds were identified, among which free sterols and their glycosides, diand triacylglycerols, monogalactosyldiglycerides and their acyl derivatives, phosphatidylglycetols, phosphatidylcholides, and phosphatidic acids predominated. The fatty acid composition, determined by GLC, was represented by 11 components, of which about 90% consisted of linoleic, palmitic, and oleic acids.A. V. Bogatskii Physicochemical Institute of the UkrSSR Academy of Sciences, Odessa. Translated from Khimiya Priorodnykh Soedinenii, No. 3, pp. 357–360, May–June, 1988.