磺酰异氰酸酯柱前衍生化法测定水分含量的方法

该发明属分析化学领域,涉及磺酰异氰酸酯柱前衍生化法测定水分含量。以磺酰异氰酸酯类化合物为衍生化试剂,对水进行柱前衍生化之后,加羟基或巯基化合物终止反应。所提供的衍生化方法测定快速、准确、简便、易于推广、成本低,还具有反应条件温和、副反应少、过量衍生化试剂不干扰水分的测定等优点,     

稳定同位素在组学研究及临床诊断中的应用

稳定同位素因其具有可示踪性、良好的稳定性和与非标记试剂化学性质相近等特点，在农残检测、样品溯源等诸多研究中起着重要作用。近年来，随着生命科学的发展和分析检测技术的不断提高，稳定同位素在药物研发、精准诊疗等与人民健康息息相关领域的重要性日益突出。介绍了稳定同位素试剂在蛋白质定量、代谢机理确证和潜在生物标记物筛选等多组学研究中的应用，还介绍了其作为内标物或原料试剂在临床质谱、核医学成像等临床诊疗中的应用，并对其未来发展进行了展望。     

衍生化气相色谱法检测化学毒剂相关化合物的试剂和方法进展

化学毒剂是高毒性的危险化学物质,时至今日仍然对人类和社会具有潜在威胁.化学毒剂及其降解产物的分析是验证化学毒剂存在的重要方法.气相色谱法以及气相色谱-质谱联用法是用于检测相关化合物的主要技术.由于许多化学毒剂的水解、降解产物具有极性大、难挥发的特点,因此需要通过衍生化试剂进行反应,成为挥发性高,低极性、低反应性的便于色...     

稳定同位素标记溴布特罗-D_9的合成

以叔丁胺-D_9为稳定同位素标记前体,制备目标化合物。以4-氨基苯乙酮为起始原料,经NBS溴化、Cu Br_2溴化后,再与叔丁胺-D_9进行胺化反应,最后使用硼氢化钠还原得到目标化合物。采用均匀设计法对胺化步骤进行研究,实验数据通过二次多项式逐步回归分析,得出了叔丁胺收率最高时各因素组合(胺化反应时间为2.5 h,溶剂三氯甲烷的用量为50 m L,n(叔丁胺-D_9)∶n(4-氨基-3,5-二溴-α-溴代苯乙酮)=2∶1)。目标化合物经过高效液相色谱外标法定量分析,其化学纯度98.0%,经过质谱检测,其同位素丰度97.0 atom%D。研制的目标化合物达到了食品安全领域中β-受体激动剂类药物检测用同位素内标试剂的要求。     

GC-MS法同时测定聚合物材料中19种有机锡化合物

建立了一种同时检测聚合物材料中19种有机锡化合物(OTCs)的方法。聚合物样品中的OTCs经超声萃取和衍生化后,采用气相色谱-质谱联用法(GC-MS)进行分析,并对萃取时间、衍生化时间、衍生化p H值、衍生化试剂用量等条件进行了优化。结果表明:该方法中19种OTCs的线性相关系数为0.998 3~0.999 9,样品加标回收率为82.33%~110.91%,相对标准偏差(RSD)为3.03%~10.72%。与常规OTCs检测方法相比,本方法样品适用性较为广泛、通用性强,且可实现多种OTCs的同时检测。     

盐酸莱克多巴胺-D6新的合成方法研究与结构表征

稳定同位素内标试剂与同位素稀释质谱法相结合的检测技术,为快速准确地检测莱克多巴胺的含量提供了可能.以4-(4-甲氧苯基)-2-丁酮为起始原料,经氢-氘交换、还原胺化、脱保护基反应,合成稳定同位素氘标记的盐酸莱克多巴胺.该合成路线具有路线短、操作简便、原料廉价易得等优点.合成产物经核磁共振氢谱(1 HNMR)和质谱(ES...     

稳定同位素标记碱性嫩黄O-D_(12)的合成研究

以CD3OD为稳定同位素标记原料,经甲基化、缩合、亚氨化等步骤合成标题化合物。以消耗的CD3OD计算收率为44.5%。目标产物经质谱(MS)、核磁(1HNMR)和高效液相色谱(HPLC)等仪器表征确认,化学纯度98.0%,同位素丰度99.0%(atom D),可作为食品安全领域检测用同位素内标试剂。     

稳定同位素标记六六六-D6的合成

以苯-D6和氯气为原料,二氯甲烷作为溶剂,在光照的条件下合成稳定同位素标记的六六六-D6,以消耗的苯-D6计算,六六六-D6收率为85.5%。经甲醇,丙酮等溶剂重结晶得到α-六六六-D6,纯度大于98%,同位素丰度为98%atom D,产品经气相、质谱等仪器表征确定为目标化合物,可作为食品安全领域检测用同位素内标试剂。     

氘标记克伦丙罗新的合成方法研究与结构表征

稳定同位素内标试剂与同位素稀释质谱法相结合的检测技术,为快速准确地检测β2受体激动剂克伦丙罗的含量提供了可能.报道了一种新型的稳定同位素氘标记克伦丙罗的合成方法,以4-氨基-3,5-二氯-α-溴代苯乙酮为原料,经改良的Gabriel方法合成了伯胺化合物,再与丙酮-D6经还原胺化反应制备了稳定性同位素标记的克伦丙罗-D7...     

稳定同位素内标试剂邻苯二甲酸二(2-乙基己)酯-D4的合成

以2-乙基己醇-D2和邻苯二甲酸酐为原料,在催化剂的催化作用下简便高效的生成标题化合物。以消耗的邻苯二甲酸酐计算,标题化合物收率可达94.5%。用质谱和核磁共振波谱等表征手段对产品结构进行确定,产品的同位素丰度为99.1 atom%D,纯度为99.0%,可作为同位素内标试剂应用于食品安全检测领域塑化剂违禁物质的检测。     

Pyrene Tags for the Detection of Carbohydrates by Label-Assisted Laser Desorption/Ionisation Mass Spectrometry**

Matrix-assisted laser desorption/ionisation mass spectrometry (MALDI-MS) is widely used for the analysis of biomolecules. Label-assisted laser desorption/ionisation mass spectrometry (LALDI-MS) is a matrix-free variant of MALDI-MS, in which only analytes covalently attached to a laser desorption/ionisation (LDI) enhancer are detected. LALDI-MS has shown promise in overcoming the limitations of MALDI-MS in terms of sample preparation and MS analysis. In this work, we have developed a series of pyrene-based LDI reagents (LALDI tags) that can be used for labelling and LALDI-MS analysis of reducing carbohydrates from complex (biological) samples without the need for additional chemical derivatisation or purification. We have systematically explored the suitability of four pyrene-based LDI enhancers and three aldehyde-reactive handles, optimised sample preparation, and demonstrated the use of LALDI tags for the detection of lactose. We have also exemplified the potential of LALDI tags for labelling carbohydrates in biological samples by direct detection of lactose in cow's milk. These results demonstrate that LALDI-MS is a promising technique for the analysis of reducing carbohydrates in biological samples, and pave the way for the development of LALDI-MS for glycomics and diagnostics.     

Quantitative Analysis of Phytosterols in Edible Oils Using APCI Liquid Chromatography–Tandem Mass Spectrometry

Previous methods for the quantitative analysis of phytosterols have usually used GC–MS and require elaborate sample preparation including chemical derivatization. Other common methods such as HPLC with absorbance detection do not provide information regarding the identity of the analytes. To address the need for an assay that utilizes mass selectivity while avoiding derivatization, a quantitative method based on LC–tandem mass spectrometry (LC–MS–MS) was developed and validated for the measurement of six abundant dietary phytosterols and structurally related triterpene alcohols including brassicasterol, campesterol, cycloartenol, β-sitosterol, stigmasterol, and lupeol in edible oils. Samples were saponified, extracted with hexane and then analyzed using reversed phase HPLC with positive ion atmospheric pressure chemical ionization tandem mass spectrometry and selected reaction monitoring. The utility of the LC–MS–MS method was demonstrated by analyzing 14 edible oils. All six compounds were present in at least some of the edible oils. The most abundant phytosterol in all samples was β-sitosterol, which was highest in corn oil at 4.35 ± 0.03 mg/g, followed by campesterol in canola oil at 1.84 ± 0.01 mg/g. The new LC–MS–MS method for the quantitative analysis of phytosterols provides a combination of speed, selectivity and sensitivity that exceed those of previous assays.     

Gas chromatography — mass spectrometric determination of unsymdimethylhydrazine in soil and water by derivatization with aromatic aldehydes

A gas chromatography — mass spectrometric method for determination of unsymdimethylhydrazine (UDMH) in soil and water has been developed. The method is based on derivatization of UDMH with 2-nitrobenzaldehyde, 4-nitrobenzaldehyde, 4-chlorobenzaldeyhde, 4-cyanobenzaldehyde, 4-dimethyaminobenzaldehyde, benzaldehyde and furfuraldehyde, followed by analysis of the derivative using gas chromatography — mass spectrometry. The effect of ambient air and antioxidants (pyrogallol and TiCl₃) to absorb dissolved oxygen from the reagents has been investigated. The method proves to be useful for UDMH analysis in soil and water, and has been used for environmental site assessment at a former missile base in Ukraine.     

Quantification of Pentafluorobenzyl Oxime Derivatives of Long Chain Aldehydes by GC–MS Analysis

Negative ion mass spectrometric techniques, for compounds having good ionization properties, such as pentafluorobenzyl derivatives, are believed to be more sensitive than positive ion methods. Preparation of PFB oximes of fatty aldehydes from crude lipid extracts is problematic due to the release of free aldehydes from plasmalogens during derivatization. Accordingly, in these studies plasmalogens were removed by silicic acid column chromatography prior to pentafluorobenzyl derivatization. This simple purification step to remove plasmalogens is shown to facilitate the quantification of long-chain aldehydes by analysis of their pentafluorobenzyl oxime derivatives utilizing gas chromatography–mass spectrometry in the negative ion chemical ionization mode. The limit of detection for long chain fatty aldehydes using this method is 0.5 pmol and it is linear over two orders of magnitude. Silicic acid column chromatography followed by electrospray ionization mass spectrometry demonstrated that plasmalogens were removed (the detection limit for this analyses was ≤0.3 pmol). Furthermore, we have exploited the utility and sensitivity of this method to identify increases in hexadecanal and octadecanal in 3-amino-1,2,4-triazole treated human neutrophils. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

有机同位素稀释质谱法在食品安全分析中的应用

有机同位素稀释质谱法具有高精度、高准确度、样品无需严格分离等优点,已广泛应用于食品安全领域.简要介绍了有机同位素稀释质谱技术的机理和特点,综述了其在食品安全领域中的应用,并对其发展趋势进行了展望.     

Investigation of Artefacts Formed in Frying Fats

The investigation of frying fats and artefacts formed in edible oils both under actual industrial frying conditions and under experimental conditions is discussed. The potential importance of instrumental liquid chromatography for the characterization and identification of oxidized oils is shown. Separation schemes and methods for the isolation and identification of fractions are discussed. Classes of artefacts consisting of dimeric fatty acids and more polar monomeric fatty acids may be isolated by preparative column, thin layer, and gel permeation chromatography and further characterized by GLC, TLC, derivatization, and mass spectrometry. The use of methoxylation, silylation, and labeling techniques for double bond and hydroxy group position determination in artefact classes by mass spectrometry is discussed.     

A Highly Selective and Sensitive Chiral Derivatization Method for High- Performance Liquid Chromatographic Determination of the Stereoisomer Composition of Natural Products With Chiral Branched Alkyl Chains

In the study of chiral biologically active compounds such as pheromones, the analysis of the stereoisomer composition is essential to gain more insight into their stereochemical diversity, which affects the pheromone communication channels and therefore the diversification of species. This mini-review summarizes the development of fluorescence derivatization reagents for high-performance liquid chromatographic (HPLC) determination of the absolute configuration and stereoisomer composition of natural products with a chiral branched alkyl chain. The diastereomeric separation of anteiso fatty acids bearing a branched methyl group up to the C-26 position was achieved by reversed-phase HPLC under very low column temperature conditions using (1S,2S)-2-(2,3-anthracenedicarboximido)cyclohexanol as a derivatization reagent, enabling fluorescent detection of these compounds at femtomole levels. This method was also applicable to chiral alcohols and amines with chiral branched methyl groups using similar reagents containing a carboxyl group. These reagents were successfully applied to determine the absolute configurations and stereoisomer composition of the chiral alkyl chain of natural compounds including some insect pheromones, miyakosyne A, and plakoside A. The combination of these reagents and two-dimensional HPLC constitutes a very powerful tool for the analysis of the stereoisomers of natural crude samples. Furthermore, the analysis of some natural bioactive substances using this method demonstrated that natural substances are not always optically pure, consisting instead of stereoisomer mixtures exhibiting stronger activity than optically pure enantiomers. These results cast doubts on the concept of biological homochirality and demonstrate that natural pheromones do not always show the highest activity among all stereoisomers.

     

Determination of Phenolic Acids and Flavonoids in Taraxacum formosanum Kitam by Liquid Chromatography-Tandem Mass Spectrometry Coupled with a Post-Column Derivatization Technique

A liquid chromatography-tandem mass spectrometry method (LC-MS/MS) was developed for the determination of phenolic acids and flavonoids in a medicinal Chinese herb Taraxacum formosanum Kitam. Initially, both phenolic acids and flavonoids were extracted with 50% ethanol in a water-bath at 60 °C for 3 h and eventually separated into acidic fraction and neutral fraction by using a C(18) cartridge. A total of 29 compounds were separated within 68 min by employing a Gemini C(18) column and a gradient solvent system of 0.1% formic acid and acetonitrile at a flow rate of 1.0 mL/min. Based on the retention behavior as well as absorption and mass spectra, 19 phenolic acids and 10 flavonoids were identified and quantified in T. formosanum, with the former ranging from 14.1 μg/g to 10,870.4 μg/g, and the latter from 9.9 μg/g to 325.8 μg/g. For further identification of flavonoids, a post-column derivatization method involving shift reagents such as sodium acetate or aluminum chloride was used and the absorption spectral characteristics without or with shift reagents were compared. An internal standard syringic acid was used for quantitation of phenolic acids, whereas (±) naringenin was found suitable for quantitation of flavonoids. The developed LC-MS/MS method showed high reproducibility, as evident from the relative standard deviation (RSD) values for intra-day and inter-day variability being 1.0-6.8% and 2.0-7.7% for phenolic acids and 3.7-7.4% and 1.5-8.1% for flavonoids, respectively, and thus may be applied for simultaneous determination of phenolic acids and flavonoids in Chinese herb and nutraceuticals.     

Species-Specific Chemical Signatures in Scale Insect Honeydew

The quantity and chemical composition of honeydew produced by scale insects may influence wider community structure, but little is known about the detailed chemical composition of the honeydew found in forest ecosystems. We used gas chromatography-mass spectrometry to examine the amino acid and carbohydrate composition of honeydew from three New Zealand communities. Low molecular weight carbohydrates (mono-, di-, and tri-saccharides) were derivatized using a modified trimethylsilyl (TMS) method, and amino and non-amino organic acids were derivatized using methylchloroformate (MCF). These recently developed derivatization methods allowed us to detect atypical compounds such as sugar alcohols, fatty acids, and non-amino organic acids, in addition to the more routinely studied compounds such as sugars and amino acids. Some compounds could not be identified and may be novel. Multivariate analysis showed that honeydew from each scale insect species had a distinctive amino acid and carbohydrate signature. We suggest these chemical signatures may influence the types of consumers that are attracted to different honeydews and may explain the characteristic communities associated with these honeydews.     

Compound-Specific 14N/15N Analysis of Amino Acid Trimethylsilylated Derivatives from Plant Seed Proteins

Isotopic analyses of plant samples are now of considerable importance for food certification and plant physiology. In fact, the natural nitrogen isotope composition (δ¹⁵N) is extremely useful to examine metabolic pathways of N nutrition involving isotope fractionations. However, δ¹⁵N analysis of amino acids is not straightforward and involves specific derivatization procedures to yield volatile derivatives that can be analysed by gas chromatography coupled to isotope ratio mass spectrometry (GC-C-IRMS). Derivatizations other than trimethylsilylation are commonly used since they are believed to be more reliable and accurate. Their major drawback is that they are not associated with metabolite databases allowing identification of derivatives and by-products. Here, we revisit the potential of trimethylsilylated derivatives via concurrent analysis of δ¹⁵N and exact mass GC-MS of plant seed protein samples, allowing facile identification of derivatives using a database used for metabolomics. When multiple silylated derivatives of several amino acids are accounted for, there is a good agreement between theoretical and observed N mole fractions, and δ¹⁵N values are satisfactory, with little fractionation during derivatization. Overall, this technique may be suitable for compound-specific δ¹⁵N analysis, with pros and cons.