Combined system and its application of thermogravimetric analysis/FT-IR

A TGA/FT-IR system and its application is described. The gases evolved from TGA were induced to the temperature controlled flow cell of an FT-IR spectrophotometer through the temperature controlled transfer pipe and were measured by FT-IR spectrophotometer. The results from the analysis of ethylene-vinyl-acetate copolymer and water-soluble paint are shown.     

应用TGA-FTIR研究不同来源污泥的燃烧和热解特性

在空气气氛下，利用热重分析方法研究了三种不同来源的污泥燃烧特性。探讨水处理工艺和污泥处理工艺对污泥中有机物的分布影响和燃烧特性影响。研究发现，污水厌氧工艺和污泥厌氧工艺均导致结构复杂、燃烧温度高的有机物生成。在氮气气氛下利用热重红外联用技术，对比研究了同种污泥的热解和燃烧特性，污泥热解主要发生有机物裂解成小分子和小分子的挥发，氧气的存在加速了污泥的裂解。污泥热解温度200℃～500℃，主要气体H2O、CO2、CO以及甲烷等烃类，CO2在高温750℃还存在一个析出峰，由于无机碳酸盐的分解。     

Ultra high performance liquid chromatography coupled with triple quadrupole mass spectrometry and chemometric analysis of licorice based on the simultaneous determination of saponins and flavonoids

Licorice is among the most popular herbal medicines and frequently used in traditional medicine, food products, and cosmetics. In China, only Glycyrrhiza uralensis Fisch., Glycyrrhiza inflata Bat. and Glycyrrhiza glabra L. are officially used and are usually processed with honey prior to use. To maintain the quality of commercially available herbal products, a simple, rapid, and reliable ultra high performance liquid chromatography with triple quadrupole mass spectrometry was developed to investigate the major active constituents of commercially available licorice products. Nineteen components were accurately determined, including eight triterpenoid saponins, one triterpene, and ten flavonoids. Subsequently, multivariate statistical analysis methods were employed to further explore and interpret the experimental data. The results indicated that liquiritin apioside may be considered as a candidate index for the quality control of licorice as well as 18β‐glycyrrhizic acid and liquiritin. In addition, both 18β‐glycyrrhizic acid and licorice‐saponin G2 can be used for discrimination between crude and honey‐processed licorice. Furthermore, using 18β‐glycyrrhizic acid and liquiritin as markers, this work revealed that the quality of licorice products may have declined in recent years. This highlights the need for additional effort focused on good agricultural practice during the processing of licorice. In summary, this study provides a valuable reference for the quality assessment of licorice.     

Classification of the medicinal plants of the genus Atractylodes using high‐performance liquid chromatography with diode array and tandem mass spectrometry detection combined with multivariate statistical analysis

Analytical methods using high‐performance liquid chromatography with diode array and tandem mass spectrometry detection were developed for the discrimination of the rhizomes of four Atractylodes medicinal plants: A. japonica, A. macrocephala, A. chinensis, and A. lancea. A quantitative study was performed, selecting five bioactive components, including atractylenolide I, II, III, eudesma‐4(14),7(11)‐dien‐8‐one and atractylodin, on twenty‐six Atractylodes samples of various origins. Sample extraction was optimized to sonication with 80% methanol for 40 min at room temperature. High‐performance liquid chromatography with diode array detection was established using a C₁₈ column with a water/acetonitrile gradient system at a flow rate of 1.0 mL/min, and the detection wavelength was set at 236 nm. Liquid chromatography with tandem mass spectrometry was applied to certify the reliability of the quantitative results. The developed methods were validated by ensuring specificity, linearity, limit of quantification, accuracy, precision, recovery, robustness, and stability. Results showed that cangzhu contained higher amounts of atractylenolide I and atractylodin than baizhu, and especially atractylodin contents showed the greatest variation between baizhu and cangzhu. Multivariate statistical analysis, such as principal component analysis and hierarchical cluster analysis, were also employed for further classification of the Atractylodes plants. The established method was suitable for quality control of the Atractylodes plants.     

GC-MS with ethyl chloroformate derivatization for comprehensive analysis of metabolites in serum and its application to human uremia

An optimized method based on GC-MS with ethyl chloroformate derivatization has been developed for the comprehensive analysis of endogenous metabolites in serum. Twenty-two reference standards and serum samples were used to validate the proposed method. The correlation coefficient was higher than 0.9900 for each of the standards, and the LOD varied from 125 to 300 pg on-column. The analytical equipment exhibited good repeatability (RSD<10%) for all of the standards. Both the repeatability and the within-48-h stability of the analytical method were satisfactory (RSD<10%) for the 18 metabolites identified in the serum samples. Mean recovery was acceptable for the 18 metabolites, ranging from 70% to 120% with RSDs of less than 10%. Using the optimized protocol and a subsequent multivariate statistical technique, complete differentiation was achieved between the metabolic profile of uremic patients and that of age- and sex-matched normal subjects. Significantly decreased levels of valine, leucine, and isoleucine and increased levels of myristic acid and linoleic acid were observed in the patient group. This work demonstrated that this method is suitable for serum-based metabolic profiling studies.     

Effect of different chemical treatments on the pyrolysis products of Quercus petraea L. heartwood

Analytical pyrolysis was applied to oak wood to provide useful information concerning the structure of oak wood components and the effect of different treatments on the chemical structure of wood components. We have studied the influence of DMSO, H₂O₂, H₂O, acetic acid, and enzymatic treatments focusing on the qualitative and quantitative aspects. We studied the evolution of syringyl (S) and guaiacyl (G) compounds (main thermal degradation products of lignins) and the evolution of mallard reaction products, and main thermal degradation products of cellulose and hemicellulose.     

Quantitative analysis of urinary endogenous markers for the treatment effect of Radix Scutellariae on type 2 diabetes rats

The effect of Radix Scutellariae treated on type 2 diabetic rats has been investigated by a liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) based urinary quantitative approach. In this research, multiple reactions monitoring mode of MS/MS in LC-MS/MS analysis was used to quantitatively analyze the concentrations of 7 endogenous compounds in urine of normal control group, type 2 diabetic model group and Radix Scutellariae-treated group, and multivariate statistical analysis was utilized for MS data processing. The above-mentioned three groups can be distinguished via pattern recognition. The obtained results indicated that Radix Scutellariae affect the urinary metabolic profiling of type 2 diabetic rats on the polyol pathway, protein glycation reaction and amino acids metabolism pathway. According to these results, Radix Scutellariae should have the pharmacological effect on preventing or delaying the onset and progression of diabetes and its complications.     

Study of interactions between Gallic Acid and Skin Surface using Infrared Spectroscopy

The transdermal transmission of model substance on the pigskin samples was investigated using the attenuated total reflection (ATR) technique of infrared (IR) spectroscopy. The collected vibrational spectroscopic data were evaluated by multidimensional statistical methods as principal component analysis (PCA), linear discriminant analysis (LDA) and partial least squares (PLS) regression which enable detection of individual substances in the skin, their identification and mutual differentiation. Gallic acid (GA), a natural phenolic anti-oxidant with many potential healing properties suitable e.g. for atopic dermatitis treatment, was used as an analyte. Effect of GA on the skin surface was examined for four different solvents namely ethanol (EtOH), methanol (MeOH), dimethyl sulfoxide (DMSO) and ultrahigh purity water (H₂O). Moreover, the effects of temperature related to GA solubility in H₂O were investigated. During the series of experiments, nonsystematic changes of untreated skin samples were observed; while systematic changes are evident after the skin treatment. The systematic effects correspond to structural changes of the skin constituents during substance penetration.     

鱼状相图研究不同无机盐对微乳液的影响

利用鱼状相图,通过改变盐的种类,研究无机盐对正辛烷-正丁醇-十二烷基硫酸钠(SDS)-水微乳体系及脂肪醇聚氧乙烯醚(AEO-7)/十二烷基硫酸钠(SDS)-正丁醇-正辛烷-水微乳体系中相微乳液形成的影响。实验中微乳液体系在正丁醇增加过程中发生Winsor I→III→II的相转变。形成WinsorⅢ型微乳液时,不同种类的盐对微乳液的影响不同。实验中以不同种类的无机盐配成SDS微乳液及AEO-7/SDS微乳液,发现在强电解质盐中,同物质的量浓度下,盐类对微乳液的作用强度Na ClKClCa Cl2Al Cl3·6H2O。在SDS微乳液中阴离子对微乳液作用强度SO42-=CO32-,而在AEO-7/SDS微乳液中,无机盐所表现出的盐效应与SDS微乳液中不同,阴离子对微乳液作用强度SO42-CO32-,无机盐的种类影响SDS和AEO-7的之间的协同作用。     

Kinetic study of a complex triangular reaction system in alkaline aqueous-ethanol medium using on-line transmission FTIR spectroscopy and BTEM analysis

The kinetics of the base-catalyzed reaction of methyl 4-hydroxybenzoate in aqueous-ethanol solvent medium was studied and analyzed via combined on-line transmission FTIR spectroscopy and Band-Target Entropy Minimization (BTEM) technique. This reaction is considered complex since it involves simultaneous hydrolysis and ethanolysis reactions of methyl 4-hydrozybenzoate (MP) to form ethyl 4-hydroxybenzoate (EP) as an intermediate and sodium 4-hydroxybenzoate as a final product. The pure component spectra of the reactive species involved in the reaction were reconstructed using BTEM technique. Their corresponding real concentrations were calculated and subsequently used for analyzing the kinetics of this triangular reaction system. The effects of temperature and solvent mixture compositions were studied. In general, the results show that the rates of both hydrolysis and ethanolysis reactions increase with temperature. Addition of ethanol to the solvent mixture also reduces the rates of the hydrolysis reactions. The effect of solvent mixture on the rate of ethanolysis reaction is more complex and influenced by at least two competing factors, namely the concentration of ethoxide ion in the solution and the stabilization effect on the reactant. The enthalpy and entropy activation parameters, ΔH^‡ and ΔS^‡, of both the hydrolysis and ethanolysis reactions were determined using the Eyring equation and the activation parameters confirm the associative nature in the elementary steps in these reactions. Finally, it is shown that the dominant synthetic pathway in this triangular system changes from direct hydrolysis of methyl 4-hydrozybenzoate to the indirect pathway via ethanolysis and then hydrolysis depending on the solvent mixture composition.     

荧光分析中铁镍锌对铜K_α射线强度的影响

能量色散X荧光分析(EDXRF)过程中,存在吸收增强效应影响分析准确性的问题。利用EDXRF测量Fe、Ni、Zn三种元素与Cu的六组伪二元系样品,根据实验结果对元素间的影响特征和影响程度进行了分析。并利用La-chance-Trail算法得到三组元素间的影响因子数值,Cu和Fe以及Cu和Zn之间的影响效应随元素含量变化较明显,分别在0.38～0.70和0.43～0.65之间,Cu和Ni之间的影响效应不明显。对Cu-Zn二元系中Cu含量实际计算结果相对误差均在5%以内。     

逐级酸处理对锡盟褐煤的结构及热解特性的影响

为了探讨高硫褐煤提质利用中酸洗处理对煤质特性的影响,以内蒙古锡盟褐煤为研究对象,依次用HF、HNO₃和HCl的酸溶液进行预处理,对原煤及其酸处理样品进行了傅里叶变换红外光谱的煤结构表征、程序升温差热-热重实验的煤热解特性研究及其反应过程的动力学分析。结果表明,HF处理对煤样的结构影响不大,HNO₃的处理明显改变了HF处理后煤样中有机质的结构,HCl处理又使HNO₃处理引起的煤样中脂肪基团CH₃的吸收峰强度变化减弱;逐级酸处理对锡盟褐煤的热解特性存在一定的影响,HF和HNO₃处理对褐煤的热解反应性具有促进作用,HCl处理对其热解反应性的影响不大。动力学分析显示,不同过程酸预处理对褐煤热解过程的影响不能单独采用热解过程的总包反应活化能进行描述,热解活化能不仅与指前因子存在着补偿效应,也与热解阶段的失重量存在一定的关联。     

Characterization of the geographical origin of Italian red wines based on traditional and nuclear magnetic resonance spectrometric determinations

Chemical characterization of Italian red wines from different geographical locations in the Apulia, region of southern Italy, have been performed by means of chromatographic, analyses routine analyses (density, alcohol content, acidity, dry extract and ash content), inductively coupled plasma-atomic emission spectrometric measurements and nuclear magnetic resonance (¹H NMR) spectrometric determinations. Multivariate statistical methods were applied separately to the analytical and NMR data. The results showed that Apulian red wines are divided in three groups according to their geographical origin.     

Differentiation of betamethasone and dexamethasone using liquid chromatography/positive electrospray tandem mass spectrometry and multivariate statistical analysis

Betamethasone and dexamethasone are two corticosteroids differing in the stereoisomery of their C-16 methyl group. These two compounds are imperfectly separated by reversed-phase liquid chromatography and their mass spectra are very similar, leading to a difficult unambiguous identification according to European criteria. A method is proposed for differentiating betamethasone and dexamethasone using liquid chromatography/tandem mass spectrometry and multivariate statistical analysis. Multiple analysis of variance was used for the justification and the selection of diagnostic ions. Principal component analysis permitted the suitability of the approach to be tested on a large number of samples. Discriminant factorial analysis was finally performed to build a decisional model based on the six most significant ions. This novel utilization of mass spectrometric data appeared efficient for the unambiguous identification of the target analytes in urine samples.     

Metabolomics analysis of Ligustri Lucidi Fructus at different harvest times during the whole growing period based on ultra-high-performance liquid chromatography with mass spectrometry

After medicinal market research, it was found that the harvest time of Ligustri Lucidi Fructus (LLF) was chaotic in practice. In order to determine the optimal harvest period of LLF to ensure its pharmacological activity, metabolomics analysis of LLF at different harvest times based on ultra-high-performance liquid chromatography-triple quadrupole-(linear ion trap)-tandem mass spectrometry was established. In this study, 166 differential metabolites (DMs) in 448 metabolites at different harvest times were screened out based on variable importance in projection value, and among them, 94 DMs with regular trends of change in relative content (59 increased and 35 decreased with the growth period) were chosen to further research. The result of the multivariate statistical analysis showed that November was the optimal harvest period of LLF. Additionally, 10-hydroxyligustroside, oleoside 11-methyl ester, and salidroside were screened out to be used as the evaluation indicators of immature LLF, while specnuezhenide, nuezhenoside G13, and neonuezhenide were the evaluation indicators of mature LLF. This study provides fundamental insight for metabolite identification and proposes the best harvest period of LLF to avoid confusion in the medicinal market.     

Rapid assessment of the impact of microwave heating coupled with UV-C radiation on the degradation of PAHs from contaminated soil using FTIR and multivariate analysis

The presence and fate of polyaromatic hydrocarbons (PAHs) in the environment are receiving a great concern. In this study, three oil-contaminated soils (industrial area, Dukhan city, and artificial soils) were utilized to examine the effect of microwave (MW) heating and UV-C irradiation on the PAHs degradation. A rapid assessment of the impact was evaluated using Fourier transform infrared (FTIR) and multivariate analysis. The total organic matter values for the maximum PAHs reduction were evaluated based on the FTIR spectra of the contaminated soils followed with the principal component analysis (PCA). The results showed that the highest total organic carbon reduction was achieved for the industrial soil sample that required a high MW power and long MW exposure time. On the other hand, the Dukhan city soil sample, which has the lowest total organic carbon, required a high MW power and short MW exposure time followed by UV-C treatment for 20 min to reach the maximal FTIR transmittance reduction. The cluster analysis was also used to evaluate the impact of MW heating, and MW heating followed by UV-C irradiation on the degradation of PAHs. The PCA results of the industrial city sample showed that neither MW treatment (100% MW, 15 min exposure time) followed by UV-C treatment for 20 min nor 10 min is significantly different from the MW treatment (100% MW, 15 min exposure time). However, for the Dukhan sample, the UV-C treatment at 10 min after high MW power and long exposure time (100% MW, 15 min exposure time) was the most efficient treatment.     

离子液体溶胀对煤直接液化残渣结构及热解性能的影响

采用四种相同阴离子不同有机链长阳离子的离子液体([EMIM][MeSO_4]、[BMIM][MeSO_4]、[HMIM][MeSO_4]和[OMIM][MeSO_4])对煤直接液化残渣(DCLR)进行溶胀处理,通过SEM、FT-IR和TG-DTG表征,分析了各离子液体溶胀对煤直接液化残渣溶胀效果、表面形貌、官能团分布、主体结构和热解性能的影响。溶胀结果表明,不同链长离子液体对煤直接液化残渣具有不同的溶胀效果,[HMIM][MeSO_4]对残渣溶胀效果最好,其溶胀度高达1.78。FT-IR表明,不同链长离子液体会不同程度地破坏煤中C-H键,使得脂肪族和芳香族类化合物的相对含量有所差异。由TG-DTG可知,不同链长离子液体溶胀对残渣热解性能的影响具有较大差异,其中,以离子液体[OMIM][MeSO_4]溶胀对残渣的热解最为有利,失重率高达47.5%;而离子液体[BMIM][MeSO_4]溶胀在一定程度上抑制了残渣的热解,其失重率低于未经溶胀处理的残渣。基于Coats-Redfern法的热解动力学分析表明,煤直接液化残渣及其溶胀残渣在低温段(180-480℃)的热解过程均符合二级反应动力学,高温段(480-825℃)均以三级和四级反应动力学为宜。另外,不同链长离子液体溶胀处理明显改变了残渣的热解活化能,其链越长残渣的热解活化能越高。     

Metabolomic profiling of rat serum associated with isoproterenol-induced myocardial infarction using ultra-performance liquid chromatography/time-of-flight mass spectrometry and multivariate analysis

An ultra-performance liquid chromatography/time-of-flight mass spectrometry (UPLC/TOF-MS)-based metabolomic approach was developed to characterize the metabolic profile associated with isoproterenol (ISO)-induced myocardial infarction (MI). Analysis of the serum samples revealed distinct changes in the biochemical patterns of ISO-induced rats. A multivariate statistical method, supervised partial least squares-discriminant analysis (PLS-DA), was then used for screening of potential biomarkers. As a result, 13 lipid biomarkers, including lysophosphatidylcholines (Lyso-PCs) and fatty acids were identified by the accurate mass measurement of TOF-MS. The relationship between abnormal lipid metabolism and the formation of MI were also studied. This work demonstrates the utility of UPLC/TOF-MS-based metabolic profiling combined with multivariate analysis as a powerful tool to further investigate the pathogenesis of cardiovascular diseases.     

石油焦与煤混合燃料热重分析研究

石油焦与煤混合燃烧是高效处理石油焦的有效方法，作者对选用的石油焦和煤不同配比的混合燃料进行了热重分析研究。使用常压高温热天平研究、分析了各配比混合燃料的热解特性和燃烧特性。并根据化学动力学方法计算了各过程的化学动力学参数，即活化能E和频率因子A0。结果表明，各混合燃料热解起始温度大致相同，随煤焦比减小，挥发分析出速率变缓，最大释放速度所对应的温度升高，最终失重率减小，挥发分释放特性指数减小；随煤焦比增大，混合燃料着火温度和燃尽温度逐渐降低，最大燃烧速率所对应的温度降低，燃烧特性指数增大；随煤焦比减小，活化能和频率因子增大。     

浅析铝土矿烧失量的差异在X-射线荧光光谱分析中造成的影响刘静,马慧侠,彭展,白万里

本文探讨了一水铝土矿与三水铝土矿烧失量的差异在X-射线荧光光谱分析中造成的影响。采用试验的方式考察了硼酸锂熔融制样过程中铝土矿的烧失量损失情况;运用理论计算分析了烧失量的损失对测量结果的影响。试验与理论分析结果表明：当采用一水铝土矿绘制工作曲线来测量三水铝土矿样品时,将导致三水铝土矿中各组分测量结果偏高;烧失量的差异对主量元素测量结果影响较大,而对微量元素测量结果影响较小;待测物质的烧失量与基准物质烧失量差异越大,测量结果的偏差也就越大。