X-荧光光谱法在测定有机物或高分子中金属及若干种非金属元素含量中的应用

本文讨论了用X-荧光光谱法测定高分子络合物中稀土金属元素的含量,有机物中的磷含量及合硅交联树脂中的硅含量。本法具有简便,用量少,又可减少化学法污染环境等优点。这是将X-荧光光谱法扩大用于有机物及高分子成分分析领域的新方法。     

某航空橡胶密封材料成分分析

采用红外光谱法对某航空橡胶密封材料成分进行定性分析,结果表明,该样品的胶种为硫化甲基硅橡胶,有机助剂为邻苯二甲酸二辛酯(DOP),无机灰分为氧化锌、硫酸钙,含量为4%。使用红外光谱法分析航空密封橡胶成分是一种经济且快速的分析方法。     

《中药红外光谱分析与鉴定》

中药是成分复杂的混合物,其分析研究与质量控制一直是科研和实践领域的重大难题。该书阐述了"中药红外光谱宏观指纹分析法"的理论基础与应用实例,提出了将红外光谱用于中药分析与质量控制的方法与特点优势。全书共9章,前两章提出了红外光谱法用于混合物分析的基本理论和方法,以及将红外光谱法用于中药质量控制的方法优势,并     

《中药红外光谱分析与鉴定》

中药是成分复杂的混合物,其分析研究与质量控制一直是科研和实践领域的重大难题。该书阐述了"中药红外光谱宏观指纹分析法"的理论基础与应用实例,提出了将红外光谱用于中药分析与质量控制的方法与特点优势。全书共9章,前两章提出了红外光谱法用于混合物分析的基本理论和方法,以及将红外光谱法用于中药质量控制的方法优势,     

用傅立叶变换拉曼光谱法测定乙醇浓度

激光拉曼光谱可以迅速准确的分析混合溶液的成分及比例,为溶液浓度检测提供了一种新的方法.以乙醇溶液为例,研究用拉曼光谱法分析溶液的浓度.     

X射线荧光光谱法分析玻璃纤维中主、次量元素成分

采用粉末压片-波长色散X射线荧光光谱法分析了中碱及无碱玻璃纤维中硅、铝、钙、镁、铁、钛、钾、钠、砷、氟等10种主、次量元素成分含量。以6个标准样品并结合两个参考样品建立校准曲线，采用DeJongh模式方程有效校正玻璃基体中元素间的吸收增强效应和重叠效应。该方法测定10个元素的精密度和准确度均较好，其相对标准偏差在0．35％～2．86％之间，对实际样品的分析结果与化学法相吻合，可应用于玻璃纤维中多元素成分的快速分析。     

聚乙烯醇与溶菌酶的相互作用及其对溶菌酶构象的影响

在生理条件下, 使用凝胶过滤色谱、荧光光谱法、差示扫描量热分析和傅里叶变换红外光谱法(FT-IR)研究了溶菌酶与聚乙烯醇(PVA)的相互作用. 结果表明PVA与溶菌酶结合形成复合物, 在它们的相互作用过程中, 溶菌酶酪氨酸的发射荧光部分被猝灭, 但是, 相互作用并没有改变酪氨酸的微环境; 差示扫描量热分析结果表明, 溶菌酶与PVA之间的相互作用没有破坏溶菌酶的高级结构; 进一步使用红外光谱法结合可增强分辨率的傅里叶去卷积技术和高斯曲线拟合技术共同用于对溶菌酶与PVA复合物冻干粉中溶菌酶酰胺I带的定量分析, 发现冻干粉溶菌酶分子中与分子间相互作用相关的β-折叠组分含量减少了, 但是, 用于衡量冻干状态蛋白质结构完整性的α-螺旋组分含量没有降低. 活性分析结果进一步确认, PVA与溶菌酶的相互作用没有破坏溶菌酶的三级结构.     

激光拉曼光谱法快速测定牛奶中三聚氰胺

建立了激光拉曼光谱法快速定性和定量检测牛奶中三聚氰胺的方法。通过在牛奶提取液中加入定量的三聚氰胺,分析相应拉曼响应值,计算出样品中三聚氰胺的含量。方法的线性范围为0.08~3.0 g/L,检出限为0.08 g/L,回收率92.5%~95.5%,标准偏差S=0.034,相对标准偏差RSD=0.16%。方法适用于牛奶中三聚氰胺的快速测定。     

聚乙烯醇与牛血清白蛋白的相互作用及对其构象的影响

在生理条件下, 使用凝胶过滤色谱、荧光光谱法、差示扫描量热分析和傅里叶变换红外光谱法(FTIR)研究了牛血清白蛋白(BSA)与聚乙烯醇(PVA)的相互作用. 实验结果表明, PVA与BSA结合形成复合物, 在其相互作用过程中, BSA色氨酸的发射荧光部分被猝灭, 但是, 相互作用并没有明显改变色氨酸的微环境; 差示扫描量热分析结果提示, BSA与PVA之间的相互作用可能破坏了PVA或BSA的分子内作用力; 用红外光谱法结合可增强分辨率的傅里叶去卷积技术和高斯曲线拟合技术共同用于对BSA与PVA复合物冻干粉中BSA酰胺Ⅰ带的定量分析, 发现冻干粉BSA分子中与分子间相互作用相关的β-折叠组分含量明显减少, 但是, 可用于衡量冻干状态蛋白质结构完整性的α-螺旋组分含量没有降低. 对冷冻干燥后样品中的可溶性BSA分析结果提示, PVA可以保护BSA冷冻干燥过程中的稳定性.     

近红外光谱法快速测定推进剂中N-甲基对硝基苯胺

采用近红外光谱法快速测定固体推进剂中N-甲基对硝基苯胺(MNA)的含量。评价了滤波平滑、一阶导数、二阶导数、多元散射校正(MSC)和标准正态变量校正(SNV)这5种不同光谱预处理方法的优化效果，基于建模参数优化结果建立了MNA定量模型，并对模型进行了准确性和重复性验证。结果表明，光谱最佳预处理方式是SNV，模型最佳主因子数为7，模型校正决定系数(R_C²)和验证决定系数(R_P²)分别为0.998 6和0.987 2，交互验证均方根误差(RMSECV)和预测均方根误差(RMSEP)分别为0.012 0和0.009 8，重复性极差和绝对误差均低于0.2%。近红外光谱法与液相色谱法测定结果相比相对偏差在6%以内，经t检验，两种方法测定结果无显著性差异。近红外光谱法快速、准确，可用于推进剂老化进程监控。     

应用双向电泳和质谱联用技术研究乳源蛋白的差异性

应用双向电泳和质谱联用技术,对不同乳源蛋白的差异性进行了研究。根据ImageMaster 2DPlatinum图像分析软件对不同乳源酪蛋白和乳清蛋白的双向电泳(2-DE)图谱进行蛋白斑点的匹配分析,获得21个存在于水牛奶中主要分布在低丰度蛋白区的酪蛋白差异蛋白点和24个存在于水牛奶中乳清蛋白差异蛋白点。这些差异蛋白点经质谱鉴定分析,得到4个属于水牛奶酪蛋白的主要组分和2个与水牛奶中酪蛋白有较高同源性的新组分,同时获得4个属于水牛奶乳清蛋白的主要组分和3个与水牛奶中乳清蛋白有较高同源性的组分。     

Short-wave near-infrared spectroscopy analysis of major compounds in milk powder and wavelength assignment

In this study, short-wave near-infrared (NIR) spectroscopy at 800–1050 nm region was investigated for the analysis of main compounds in milk powder. Through quantitative analysis, the feasibility is further demonstrated for the simultaneous measurement of fat, proteins and carbohydrate in milk powder. Two models, partial least-squares and least-squares support vector machine, were compared and utilized for regression coefficients and loading weights. The affect of standard normal variate spectral pretreatment to model performance was evaluated. Based on the resulted coefficients and loading weights, interesting wavelength regions of nutrition in milk powder are screened and the assignment of all specific wavelengths is firstly proposed in the details associated with chemical base. Instead of the whole short-wave NIR spectral data, these assigned wavelengths which can be reliably exploited were used for the content determination. Compared with other spectroscopy technique, assigned short-wave NIR spectral wavelengths did a good work. Determination coefficients for prediction are 0.981, 0.984, and 0.982, respectively for three components. The proposed wavelength assignment in the short-wave NIR region could be used for the component contents determination of milk powder, and could be as a guidance to interpret the spectra of milk powder.     

Identification of Silymarin Constituents: An Improved HPLC–MS Method

A high-performance liquid chromatographic/tandem mass spectrometric method was developed for the determination of the major bioactive flavonolignans in silymarin, a herbal remedy extracted from the milk thistle Silybum marianum. In this study, eight active components of silymarin with the same elemental composition, including silychristins A and B, silydianin, silybin A and B, isosilybin A and B and an unknown compound were completely separated. Furthermore, three additional components were detected and partly separated; presumably two silybin stereoisomers and one isosilybin stereoisomer. The collision-induced dissociation (CID) MS/MS spectra of these silymarin constituents were studied: the spectral similarity values of the component pairs were determined, and simple criteria were found for distinguishing the components.

     

Artificial neural network for simultaneous determination of two components of compound paracetamol and diphenhydramine hydrochloride powder on NIR spectroscopy

Diffuse reflectance near-infrared (NIR) spectroscopy is a technique widely used for rapid and non-destructive analysis of solid samples. A method for simultaneous analysis of the two components of compound paracetamol and diphenhydramine hydrochloride powdered drug has been developed by using artificial neural network (ANN) on near-infrared (NIR) spectroscopy. An ANN containing three layers of nodes was trained. Various ANN models based on pretreated spectra (first-derivative, second-derivative and standard normal variate; SNV) were tested and compared, respectively. In the models the concentration of paracetamol and caffeine as active principles of compound paracetamol and diphenhydramine hydrochloride powder was determined simultaneously. Partial least squares regression (PLS) multivariate calibrations were also used, which were compared with ANN. The best model was obtained at first-derivative spectra. We have also discussed the parameters that affected the networks and predicted the test set (unknown) specimens. The degree of approximation, a new evaluation criteria of the network were employed, which proved the accuracy of the predicted results.     

Radial basis function neural networks in non-destructive determination of compound aspirin tablets on NIR spectroscopy

The application of the second most popular artificial neural networks (ANNs), namely, the radial basis function (RBF) networks, has been developed for quantitative analysis of drugs during the last decade. In this paper, the two components (aspirin and phenacetin) were simultaneously determined in compound aspirin tablets by using near-infrared (NIR) spectroscopy and RBF networks. The total database was randomly divided into a training set (50) and a testing set (17). Different preprocessing methods (standard normal variate (SNV), multiplicative scatter correction (MSC), first-derivative and second-derivative) were applied to two sets of NIR spectra of compound aspirin tablets with different concentrations of two active components and compared each other. After that, the performance of RBF learning algorithm adopted the nearest neighbor clustering algorithm (NNCA) and the criterion for selection used a cross-validation technique. Results show that using RBF networks to quantificationally analyze tablets is reliable, and the best RBF model was obtained by first-derivative spectra.     

Rapid and efficient purification of cimetropium bromide and mifentidine drug metabolite mixtures derived from microsomal incubates for analysis by mass spectrometry.

A comparative study of the use of organic solvent extraction versus Sep-Pak C18 cartridges in the recovery and analysis of phase I (unconjugated) drug metabolites using mass spectrometry is presented. Standard mixtures of putative metabolites of the anticholinergic drug cimetropium bromide and the H2-antagonist mifentidine were purified from inactivated liver microsomal preparations using both methods, and subsequently the recovery of each compound was quantitated. In general, the percentage recovery and degree of purification were greater when using Sep-Pak C18 cartridges compared with organic solvent extraction. Even more efficient recovery was achieved when zinc sulphate precipitation of proteins in the liver microsomal mixtures was carried out prior to analysis. Also, the HPLC-grade solvents used in this study contained a variety of ultraviolet-inactive, hydrophobic components. This leads to problems of suppression in fast atom bombardment mass spectrometric analysis. Using Sep-Pak C18 cartridges directly prior to analysis by fast atom bombardment with single or tandem mass spectrometry leads to far superior mass spectral results compared with organic solvent extraction.     

Use of high-performance liquid chromatography-thermospray mass spectrometry and gas chromatography-electron-impact mass spectrometry in the identification of the metabolites of alpha-methylacetohydroxamic acids, potential anti-asthmatic agents

Two potential anti-asthmatic alpha-methylacetohydroxamic acids, compound 1 and compound II were metabolised to two major products (metabolite 1 and metabolite 2) after oral dosing to rabbits. Metabolite 1, extracted under acid conditions from the plasma and urine of dosed animals, was identified as a glucuronide by incubation with beta-glucuronidase and subsequent high-performance liquid chromatographic-mass spectrometric (HPLC-MS) analysis of the aglycone. HPLC-MS analysis of metabolite 2 suggested that it was the acetamide, however, unequivocal identification was obtained by further analysis using gas chromatography-mass spectrometry (GC-MS) of its trimethylsilyl derivative and by comparison with the mass spectra of the authentic acetamides. This study shows the advantages of combining HPLC-MS with other techniques such as GC-MS for the identification of metabolites.     

Direct determination of Fe and Zn in different components of cow milk by FAAS with a high performance nebulizer

Methods for the direct determination of iron and zinc in different components of cow milk (whole milk, non fat milk and whey milk) by flame atomic absorption spectrometry (FAAS) were performed using two nebulizers (nebulizer of platinum with a glass impact bead and a high performance nebulizer). The non fat milk and the whey milk were obtained by physical procedures (centrifugation and ultracentrifugation) in absence of chemical treatment. A limit of detection of 0.024 and 0.007 mug ml(-1) for iron and zinc, respectively, were obtained by using a high performance nebulizer. The precision obtained varied between 1.4-4.0% and 0.4-1.9% for iron and zinc, respectively. The accuracy of the methods was studied with the analysis of SRM-1549 and A-11 non fat milk reference materials. The methods were applied to ten cow milk samples. Dates about the distribution of iron and zinc into the different components of cow milk were present.     

Derivatization of beta-dicarbonyl compound with 2,4-dinitrophenylhydrazine to enhance mass spectrometric detection: application in quantitative analysis of houttuynin in human plasma

Houttuynin (decanoyl acetaldehyde), a beta-dicarbonyl compound, is the major antibacterial constituent in the volatile oil of Houttuynina cordata Thunb. In the present work, detection of houttuynin in human plasma based on the chemical derivatization with 2,4-dinitrophenylhydrazine (DNPH) coupled with liquid chromatography/tandem mass spectrometry was described. The primary reaction products between the beta-dicarbonyl compound and DNPH in aqueous phase were identified as heterocyclic structures, of which the mass spectrometric ionization and fragmentation behavior were characterized with the aid of high-resolution multistage mass spectral analysis. For quantification, houttuynin and internal standard (IS, benzophenone) in plasma were firstly converted to their DNPH derivatives without sample purification, then extracted from human plasma with n-hexane and detected by liquid chromatography tandem mass spectrometry performed in selected reaction monitoring (SRM) mode. This method allowed for a lower limit of quantification (LLOQ) of 1.0 ng/ml using 100-microl plasma. The validation results showed high accuracy (%bias < 2.1) and precision (%CV < 7.2) at broad linear dynamic range (1.0-5000 ng/ml). The simple and quantitative derivatization coupled with tandem mass spectrometric analysis facilitates a sensitive and robust method for the determination of plasma houttuynin in pharmacokinetic studies.     

Drug detection in hair by chromatographic procedures.

This article reviews the analysis of 31 drugs and drug metabolites in human hair by thin-layer chromatography, high-performance liquid chromatography, gas chromatography, gas chromatography-mass spectrometry and mass spectrometry. The most important detection method after chromatographic separation of the components is the mass spectrometry because of its sensitivity and specificity. Washing steps to exclude external contamination, extraction, derivatization, stationary phases, detection modes and detection limits of the mass spectrometric and gas chromatographic-mass spectrometric procedures are presented in five tables. Additionally, a method for a gas chromatographic-mass spectrometric screening procedure is presented.