Liquid chromatographic method with on-line UV spectrum identification and off-line thin-layer chromatographic confirmation for the detection of tranquillizers and carazolol in pig kidneys

A method for the detection and identification of residues of veterinary tranquillizers and the β-blocker carazolol in kidneys of slaughtered pigs was developed. The method is based on liquid chromatography with UV spectrum identification. Additional confirmation can be obtained with two-dimensional thin-layer chromatography. Limits of identification range from less thann 1 to 2.5 μg kg^?1, depending on the residue. The method was used in a surveillance study in The Netherlands.     

Identification and discrimination of bacterial strains by laser induced breakdown spectroscopy and neural networks

A method based on laser induced breakdown spectroscopy (LIBS) and neural networks (NNs) has been developed and applied to the identification and discrimination of specific bacteria strains (Pseudomonas aeroginosa, Escherichia coli and Salmonella typhimurium). Instant identification of the samples is achieved using a spectral library, which was obtained by analysis using a single laser pulse of representative samples and treatment by neural networks. The samples used in this study were divided into three groups, which were prepared on three different days. The results obtained allow the identification of the bacteria tested with a certainty of over 95%, and show that only a difference between the bacteria can cause identification. Single-shot measurements were sufficient for clear identification of the bacterial strains studied. The method can be developed for automatic real time, fast, reliable and robust measurements and can be packaged in portable systems for non-specialist users.     

Comparison of the reliability of the identification with diode array detector and mass spectrometry

The reliability of compound identification by low resolution mass spectrometry (MS) was quantitatively compared with that for diode array detection (DAD). The quantity of the information obtained with one parent ion and two characteristic daughter ions at low resolution MS-MS was compared with that obtained by UV-vis spectra with large wavelength range from DAD. It was shown that if the UV-vis spectra are reproducible, i.e. with low RSD values for selected wavelengths and relative absorption, the reliability of the identification with DAD is comparable with the one for low resolution MS-MS. Because the sensitivity of the DAD is one or two orders of magnitude lower than that of mass spectrometry, on-column focusing was applied and reliable identification was achieved at 1 ppb concentration. The surprisingly high reliability of identification obtained with contemporary DADs should increase the analysts' confidence in this method of detection/confirmation.     

典型塑料载体与助燃剂燃烧残留物的闪蒸气相色谱-质谱分析

通过对火场常见塑料载体与助燃剂混合燃烧残留物的分析,发展一种适用此类燃烧残留物的火灾物证鉴定方法,对火场中是否存在助燃剂进行判断,避免漏检情况的发生。应用热分析技术确定合适的闪蒸温度,在此温度下对塑料载体与助燃剂混合燃烧残留物进行闪蒸分析,并从实验条件选择、可行性分析、定性分析三方面对闪蒸技术进行评价。结果表明,闪蒸气相色谱-质谱（Flash GC-MS）技术可以检测到热塑性聚合物塑料载体与助燃剂混合燃烧残留物中残留的助燃剂特征组分,可对火场中是否存在过助燃剂进行辨别。闪蒸气相色谱-质谱技术丰富了现代火灾物证鉴定技术,能进一步辅助火灾物证鉴定工作,使鉴定结论更准确、可靠。     

Identification of Vodkas by Ion Chromatography and Gas Chromatography

Vodka samples from various distilleries were analyzed by ion chromatography in combination with gas chromatography for the identification of alcoholic products. It was shown that vodkas of the same name manufactured at the same distillery exhibited relatively stable anion–cation compositions; therefore, the ionic composition of vodka can serve as an identification feature. The use of methanol, 2-propanol, and 1-propanol concentrations, which were determined by gas chromatography, as identification features of vodka enhances the probability of detecting adulterated alcoholic products.     

Identification and quantification of protein carbonylation using light and heavy isotope labeled Girard's P reagent

Protein carbonyls are one of the most widely studied markers of oxidative stress. Determining increases in the concentration of protein carbonyls known to be associated with neurodegenerative diseases, heart disease, cancer and ageing. Identification of carbonylation sites in oxidized proteins has been a challenge. Even though recent advances in proteomics has facilitate the identification of carbonylation sites in oxidized proteins, confident identification remains a challenge due to the complicated nature of oxidative damage and the wide range of oxidative modifications. Here, we report the development of a multiplexing strategy that facilitates confident carbonylated peptide identification through a combination of heavy and light isotope coding and a multi-step filtering process. This procedure involves (1) labeling aliquots of oxidized proteins with heavy and light forms of Girard's reagent P (GPR) and combining them in a 1:1 ratio along with (2) LC/MS and MALDI-MS/MS analysis. The filtering process uses LC/MS and MALDI-MS/MS data to rule out false positives by rejecting peptide doublets that do not appear with the correct concentration ratio, retention time, tag number, or resolution. This strategy was used for the identification of heavily oxidized transferrin peptides and resulted in identification 13 distinct peptides. The competency of the method was validated in a complex mixture using oxidized transferrin in a yeast lysate as well as oxidized yeast. Twenty-five percent of the peptides identified in a pure oxidized sample of transferrin were successfully identified from the complex mixture. Analysis of yeast proteome stressed with hydrogen peroxide using this multiplexing strategy resulted in identification of 41 carbonylated peptides from 36 distinct proteins. Differential isotope coding of model peptides at different concentrations followed by mixing at different ratios was used to establish the linear dynamic range for quantification of carbonylated peptides using light and heavy forms of GPR.     

化学键的高选择性拓扑指数及应用

基于分子和原子的高选择性拓扑指数, 提出了化学键的高选择性拓扑指数bATID. 分别采用300余万个化学键的虚拟数据集和实际数据集检验bATID的唯一性, 未发现简并, 即bATID具有较强的化学键区分能力. 进一步将bATID应用于有机化合物的化学键识别, 获得了较好结果. 如, 利用bATID可识别出富勒烯C₆₀的90个化学键为30个6∶6键和60个5∶6键. 研究还表明, bATID的化学键识别可应用于手性中心自动设定和自同构群穷举生成的顶点置换.     

Screening and Identification of Many of the Compounds Present in Rauvolfia verticillata by Use of High-Pressure LC and Quadrupole TOF MS

A simple approach is described for LC–Q-TOFMS screening and identification of many of the compounds present in Rauvolfia verticillata. Combined isolation and identification of the complex chemical composition was conducted when investigating traditional Chinese medicine. Twenty-two components of Rauvolfia verticillata were identified by comparing retention times and molecular weights with those of available standards and with reference data. This study provided a rapid, sensitive, economical, and systematic method for identification and evaluation of the quality of complex traditional Chinese medicines.     

Determination of embutramide and pentobarbital in meat and bone meal by gas chromatography-mass spectrometry.

An analytical procedure, consisting of multiple steps, was developed for the analysis of meat and bone meal for two veterinary drugs, embutramide and pentobarbital, used for euthanasia. After a combined extraction, embutramide was converted to its trimethylsilylether derivative and pentobarbital was methylated. Both analytes were determined by gas chromatography-mass spectrometry in the electron impact or chemical ionisation mode. Limits of determination and identification were between 50 and 100 micrograms kg-1 depending on the compound and the ionisation technique applied. Particular attention was focused on the identification of the analytes.     

中药方剂化学成分液质联用分析中标准质谱库的建立和应用

利用电喷雾离子化四级杆飞行时间串联质谱(ESI-Q-TOF)技术,以四物汤类方为例,建立了类方成分的液质联用分析质谱库。利用Masslynx工作站的Chromalynx模块的检索和与质谱库比较的功能,可以快速鉴定色谱图中各个色谱峰。此方法可应用于液质联用检测系统的谱库检测,提高了对类方成分鉴定的效率和可靠性。本质谱库共收录了液质联用条件下57个四物汤类方标准品的质谱信息,包括正负离子模式下各成分的保留时间、准分子离子峰及其碎片离子的精确质量数。该质谱库支持标准NIST谱图检索及比对方法,可自动完成总离子流色谱图中各色谱峰的识别、质谱图提取及鉴定。     

Two-step protease digestion and glycopeptide capture approach for accurate glycosite identification and glycoprotein sequence coverage improvement

A novel two-step protease digestion and glycopeptide capture approach has been developed. It is different from traditional tryptic digestion, glycopeptide enriching and identification approach in glycoproteomics. Here, proteins were first digested by Lys-C into relatively large peptides. Glycopeptides among them were selectively captured by hydrazide resin through oxidized glycans. After thorough washing steps, trypsin was used as a second protease to in situ release non-glycosylated part (named as LT-peptides) from glycopeptides. Subsequently, the remaining part of glycopeptides on resin was de-glycosylated by peptide-N-glycosidase F, and collected as DG-peptides. Finally, both LT- and DG-peptides could be analyzed by mass spectrometer, achieving glycoprotein and glycosite identification. The approach was applied to cell lysate after positive validation by a model glycoprotein: 143 N-glycoproteins identified from DG- and LT-fraction both. In those glycoproteins, 189 DG-peptide-revealed N-glycosites got further confirmation by neighboring LT-peptides, which, in the meantime, made 109 glycoproteins get improved sequence coverage with increase even up to 350% (averagely 79.4%). Through controllable release, separate identification and combined interpretation of non-glycopeptides (newly introduced LT-peptides here) and traditional de-glycopeptides, the approach could not only achieve routine N-glycosite identification, but also provide further proofs of N-glycosites and increase glycoprotein sequence coverage.     

Use of liquid chromatography-diode-array detection and mass spectrometry for rapid product identification in biotechnological synthesis of a hydroxyprogesterone

In exploratory scale biotechnological process development, the product must be rapidly identified although a reference compound may not always be available. LC-diode-array detection and MS were used for this purpose in a process producing 9alpha-hydroxyprogesterone from progesterone as substrate. The electrospray ionization mass spectrometer was combined with an ion trap mass spectrometer for the second generation MS. The preliminary identification, which could be carried out within the course of a day, confirmed that the product was a hydroxyprogesterone. The final identification step, which was much more material intensive and hence time consuming, involved a two-step preparative separation to yield quantities necessary for definitive product identification based on 1H- and 13C NMR.     

钼酸铵溶液配制方法的探讨及优化

本文针对无机化学实验中钼酸铵溶液的配制方法及使用过程中存在的问题进行了理论分析与实验探究,提出了一种简便可行的钼酸铵溶液配制方法。磷酸根离子鉴定实验结果表明,新方法所配制的钼酸铵溶液检验现象明显且无干扰,在教学实践中取得了理想的效果。该溶液放置一定时间后,检验磷酸根现象与之前无异,便于实验室长期储备。     

Increasing the reliability of the identification by high-performance liquid chromatography by means of selective and/or sensitive detection

An approach for quantitative assessment of the reliability of identification at high-performance liquid chromatography is proposed. The quantitative assessment of identification is useful for determination of selectivity at validation of the analytical methods. Chromatograms and spectra of the analytes are presented as maps in which characteristics as retention times, detector's signals, maxima and minima and another characteristics of spectra are used for identification. A formula for quantitative determination of the contribution of these characteristics on the reliability of identification is given. Using the more selective diode array detector than the convenient UV detector increases the reliability by several orders. A similar result was obtained when the UV detector was replaced with the more sensitive and selective fluorescence detector. Despite of the small contribution of the separation to the reliability its influence is very important for distinguishing of isomers because their spectra are identical.     

Feasibility study on identification of green, black and Oolong teas using near-infrared reflectance spectroscopy based on support vector machine (SVM)

Near-infrared (NIR) spectroscopy has been successfully utilized for the rapid identification of green, black and Oolong teas. The spectral features of each category are reasonably differentiated in the NIR region, and the spectral differences provided enough qualitative spectral information for identification. Support vector machine as a pattern recognition was applied to attain the differentiation of the three tea categories in this study. The top five latent variables are extracted by principal component analysis as the input of SVM classifiers. The identification results of the three tea categories were achieved by the RBF SVM classifiers and the polynomial SVM classifiers in different parameters. The best identification accuracies were up to 90%, 100% and 93.33%, respectively, when training, while, 90%, 100% and 95% when test. It was obtained using the RBF SVM classifier with sigma=0.5. The overall results ensure that NIR spectroscopy combined with SVM discrimination method can be efficiently utilized for rapid and simple identification of the different tea categories.     

Application of pattern recognition and piezoelectric sensor array for the detection of organic compounds

Organic vapours were measured by an array of piezoelectric crystal detectors. Quartz crystals were coated by different GC stationary phases. Four coated crystals were placed in an array and pattern recognition was used for identification of the compounds including acetone, benzene, chloroform and pentane. A computer program was developed for the measurement of the frequency changes and data processing. Pattern recognition method using feature extraction was applied for identification of analytes.     

表面修饰探针纳升电喷雾质谱脂质组学对大型溞和蚤状溞的快速鉴别

采用表面修饰探针敞开式纳升电喷雾质谱技术建立了脂质组学方法,以实现溞属(Daphnia)生物大型溞和蚤状溞的快速鉴别.采用微尺度表面修饰探针直接从Daphnia体内萃取和富集出脂质化合物,然后在常压敞开条件下进行纳升电喷雾质谱分析,利用高分辨率质谱仪获得脂质指纹图谱并进行脂质种类和结构鉴定.采用该方法获得了大型溞和蚤状溞的脂质指纹图谱,并研究了大型溞和蚤状溞体内的脂质组成特征.通过结合化学计量学手段实现了大型溞和蚤状溞的快速区分,并鉴定了相关的生物标志物.结果表明,所建立的微萃取探针纳升电喷雾质谱脂质组学方法具有分析速度快、灵敏度高的优点,可用于Daphnia属生物的快速鉴定和识别.     

Identification and quantitation of cis-ketoconazole impurity by capillary zone electrophoresis-mass spectrometry

trans-Ketoconazole was identified and quantified as impurity of cis-ketoconazole, an antifungal compound, by capillary zone electrophoresis-electrospray-mass spectrometry (CZE-ESI-MS). The chirality of this impurity was demonstrated separating their enantiomers by adding heptakis-(2,3,6-tri-O-methyl)-beta-cyclodextrin to the separation buffer in capillary electrophoresis (CE) with UV detection. However, MS detection was hyphenated to the CE instrument for its identification. As both compounds are diastereomers, they have the same m/z values and are needed to be separated prior to the MS identification. A 0.4M ammonium formate separation buffer at pH 3.0 enabled the separation of the impurity from cis-ketoconazole. Under these conditions, the optimization of ESI-MS parameters (composition and flow of the sheath-liquid, drying temperature, drying gas flow, and capillary potential) was carried out to obtain the best MS sensitivity. CZE-ESI-MS optimized conditions enabled the identification of trans-ketoconazole as impurity of cis-ketoconazole. In addition, the quantitation of this impurity was achieved in different samples: cis-ketoconazole standard and three different pharmaceutical formulations (two tablets and one syrup) containing this standard. In all cases, percentages higher than 2.0 were determined for the impurity. According to ICH guidelines, these values required the identification and quantitation of any impurity in drug substances and products.     

超高效液相色谱-质谱法同时测定舒血宁注射剂中20种黄酮醇苷与萜类内酯成分

建立了舒血宁注射剂中16种黄酮及4种萜类内酯同时定量的超高效液相色谱-质谱分析方法,并采用所建立的方法同时测定了不同厂家舒血宁注射剂产品中上述20种化合物的含量。注射剂样品经甲醇-水(体积比1∶1)稀释后,在Acquity UPLC BEH Shield RP18(2.1 mm×100 mm,1.7μm)色谱柱上分析,以0.1%(体积分数)甲酸水溶液-乙腈为流动相进行梯度洗脱,以电喷雾离子源负离子多反应监测(MRM)模式进行质谱监测。结果表明:20种化合物可在10 min内完成色谱分离分析,检出限和定量下限分别为0.02~1.59 ng/mL和0.07~5.30 ng/mL,16种黄酮及4种萜类内酯在各自的线性范围内线性关系良好,在低、中、高3个加标水平下的回收率为85.9%~109%。该方法前处理简单、快速高效、准确性高,为舒血宁注射剂的质量控制提供了参考。     

自动化质谱图解卷积和鉴定系统用于鉴定含痕量杂原子的石油馏分（英文）

Here we present a simple yet effective gas chromatography-mass spectrometry (GC-MS) identification approach for the detection of heteroatom-containing compounds (HACCs) in petroleum fractions. The MS/AMDIS (Automated Mass Spectral Deconvolution and Identification System) program was used to identify parts per million (ppm) HACC concentrations in petroleum fractions in place of traditional techniques (extraction and standard injection). Polycyclic aromatic sulfur heterocycles (S-PAHs) were used as model compounds to confirm the validity of the AMDIS identifiers, which were compared with extracted results using the off-line X-calibur software. AMDIS was able to identify ppm concentrations of S-PAHs in oil condensate. There was good agreement between experimental and AMDIS identification results for S-PAHs in oil condensate. AMDIS was also used to detect nitrogen-containing compounds (NCCs) and alkylphenols in oil condensate. Our results confirmed the presence of 2-methylbenzothiazole, carbazole, and 2,4-ditertbutyl phenol. In a crude oil sample, AMDIS identification of m/z=191 biomarkers was consistent with empirical results. Therefore, AMDIS can help to reduce the number of experimental steps in identification protocols.