用熵最小算法解析桂郁金挥发油GC-MS重叠谱

采用气相色谱-质谱(GC-MS)联用技术对桂郁金中提取的挥发油成分进行检测,同时用熵最小算法对其中的共流物色谱峰进行解析,并通过质谱库检索和程序升温保留指数相结合的方式对解析得到的各纯组分进行定性分析。将桂郁金挥发油各组分的质谱数据直接与美国国家标准及技术研究所(NIST)数据库进行比对,鉴定出38个化合物;在挥发油的色谱图中,存在一些因分离不完全而导致的共流物色谱峰,以保留时间为1 106.52~1 108.38 s及1 184 s的色谱峰为例,经熵最小算法解析,共发现5个纯组分。采用熵最小算法可以清楚地对共流物色谱峰进行解析并得到所包含的各个纯组分,该法可提高复杂成分定性定量分析结果的准确性。     

气相色谱-质谱法与化学计量学分辨法分析当归须挥发油中化学成分

本文借助化学计量学分辨方法,建立了用气相色谱-质谱(GC-MS)联用法分析当归须挥发油成分的方法.对重叠色谱峰采用直观推导式演进特征投影算法进行分辨,从而获得每一组分的纯色谱和质谱,依靠每一组分纯质谱在NIST质谱库进行相似性检索而定性分析,用总体积积分法进行定量分析.在当归须挥发油中共分辨出86个色谱峰,通过质谱库检...     

气相色谱/质谱结合化学计量学解析方法用于植物精油成分分析

使用气相色谱/质谱(GC-MS)法对缬草精油和含有缬草精油的混配精油的化学成分进行了分析.采用直观推导式演进特征投影法(HELP)对二维数据中的色谱重叠峰进行了解析,得到两种精油的各个物质的纯色谱和纯质谱,同时利用交互移动窗口因子分析法(AMWFA)直接比较两种精油中的共有组分,提取出共有组分的纯质谱,通过与HELP法解析出的质谱进行比较,发现AMWFA法比HELP法能更快速鉴别出混配精油中的缬草精油.     

大叶桉叶挥发油的化学成分研究

用挥发油提取器提取大叶桉干叶中的挥发油,利用色质联用(GC/MS)产生的双线性数据,藉化学计量学分辨方法,得到了各组分的纯物质色谱峰和质谱图。根据色谱保留时间,同时利用解析所得的纯物质质谱图在NIST质谱数据库进行相似检索来对各个组分进行定性分析;采用色谱峰面积归一法计算各化合物的相对含量。共分离了113个化合物,鉴定了其中90个,占总挥发油的93.28%。主要为萜类、萜醇类等化合物,还成功地检测出一些色谱分离不完全和低含量的组分。     

利用气相色谱/质谱-化学计量学分辨法分析川芎挥发性成分

采用加速溶剂萃取法提取挥发性成分,气相色谱-质谱(GC-MS)联用分析,并借助化学计量学分辨方法,对川芎的挥发性成分进行了定性定量分析。通过采用子窗口因子分析法对重叠色谱峰进行分辨,从而获得每一组分的纯色谱和质谱。依靠每一组分纯质谱在NIST质谱库进行相似性检索而定性分析,用总体积积分法进行定量分析。在川芎挥发油中共分辨出67个色谱峰,通过质谱库检索得到其中56个组分的定性定量结果,占总含量的87.67%。该方法增加了可鉴定化合物的数目,提高了定性的准确度,能用于川芎的质量控制。     

兴安落叶松针叶挥发油的GC-MS和启发渐进式特征投影法分析

采用水蒸气蒸馏法提取兴安落叶松针叶挥发油,利用气相色谱.质谱(GC-MS)联用对挥发油进行成分测定,并对其重叠色谱峰采用启发渐进式特征投影(HELP)法进行分辨,得到各组分的纯色谱峰和质谱,然后采用峰面积归一化法确定各化合物的相对含量.共分离出110种化合物,鉴定了70种化合物,占挥发油总量的93.09%,其中单萜、倍半萜和二萜的含量分别为31.92%、53.29%和6.91%.     

GC-MS结合保留指数对中药挥发油的定性

利用GC-MS联用和化学计量学方法,对6种中药挥发油进行分析,对其中的重叠色谱峰采用直观推导式演进特征投影法(HELP)法进行了分辨,同时计算了各组分的程序升温保留指数,通过质谱库定性.得到共有成分32个.结果表明,保留指数有很好的重复性,可与质谱库结合用作物质的定性.     

一种新型交替迭代算法用于农药GC-MS信号快速分析

化学计量学算法为重叠GC-MS信号解析提供了有效手段. 免疫算法(IAs)可根据标准样品的信号(色谱或质谱)对重叠GC-MS信号进行解析并得到重叠信号中各组分的信息. 但是标样信号与实际测量信号之间的差别会造成解析结果出现偏差. 针对标样信号与测量信号不一致的问题, 作者提出了一种交替迭代算法用于重叠GC-MS测量信号的直接解析. 该方法在不提供标样信号的情况下可以解析出组分的质谱和色谱信息. 计算过程中, 采用随机产生的质谱作为初始输入, 利用最小二乘和IA算法交替计算质谱和色谱, 直到满足终止条件. 采用所建立的方法对40种组分的农药混合物进行了分析, 使用快速升温程序在10 min保留时间内得到了全部组分的色谱和质谱信息.     

模差渐进投影法解析重叠色谱峰

提出了一种鉴别重叠色谱峰类型的化学计量学方法——模差渐进投影(MDEP)法。该方法利用二维色谱数据中相邻两个色谱流出点的光谱矢量模的和与该两个矢量和的模之差,建立模差-时间(dm-t)曲线判断非纯色谱峰的纯组分区,同时判定第二组分色谱流出点和倒数第二组分色谱结束点。分别以纯组分区的光谱矢量建立正交阵对该色谱峰进行投影运算,得到投影后转换色谱。该转换色谱消除了纯组分区所对应化合物的色谱和光谱信息。对转换色谱重复上述操作至整个色谱峰的模差-时间曲线均为0时终止,得到重叠色谱峰各组分的色谱流出点和结束点。利用上述结果,采用不包含待测组分光谱信息的该重叠峰二维色谱数据建立正交矩阵对该色谱峰进行投影运算,获得待测组分的相似色谱图。通过比对分析即可得到该组分在重叠色谱峰中的光谱和色谱信息。依次操作,即可获得重叠色谱峰中各组分的光谱和色谱信息。采用模差渐近投影法对4组分模拟重叠二维色谱峰及杜香挥发油GC-MS的重叠色谱峰进行了解析,方法简便、结果准确。     

福州小花茉莉全花期中的花源质量稳定性研究I．精油化学成分分析

〕本文着重报道通过福州茉莉花精油在全花期内的成分分析,以进行对福州茉莉花源质量稳定性的考察。我们连续三年在茉莉开花期中的不同季节分别采集花样,用同时蒸馏-萃取法提取精油,采用石英毛细气相色谱（CGC）和色-质谱GC/MS对精油成分进行分析。实验结果表明花期内各季节的气候起伏虽对精油成分含量有些影响,但总的看来,福州茉莉花源质量在全花期内基本是稳定的。     

Lower limit of detection achieved by raw band-target entropy minimization (rBTEM) for trace and coeluted gas chromatography-mass spectrometry components

Full-scan gas chromatography-mass spectrometry (GC-MS) provides rapid untargeted screening and detection for trace and coeluting components. Even though modern mass spectrometers have sufficient sensitivity to detect signals of trace components, this does not translate to the ability of the data-processing approach to isolate interference signals and extract pure component spectra. The raw band-target entropy minimization (rBTEM) approach based on band-target entropy minimization was previously reported to enable accurate spectra reconstruction from severely coeluting and trace GC-MS components. In this study, we evaluate the limit of detection for the approach. This study is systematically compared to classical spectral deconvolution for measurements of chlorpyrifos pesticide standards sampled with solid-phase microextraction at various concentration levels in both distilled and seawater media. The rBTEM approach was able to detect chlorpyrifos at 0.5?ppb in distilled water and 1.0?ppb in seawater while the classical approach provided numerous false negative results. In addition, rBTEM consistently provided higher match scores for chlorpyrifos. Attaining accurate identification of trace and coeluting components from full-scan GC-MS analysis has immense potential impact in biomedical, agricultural, and environmental work.     

Pure component spectral reconstruction from mixture data using SVD, global entropy minimization, and simulated annealing. Numerical investigations of admissible objective functions using a synthetic 7-species data set

A combination of singular value decomposition, entropy minimization, and simulated annealing was applied to a synthetic 7-species spectroscopic data set with added white noise. The pure spectra were highly overlapping. Global minima for selected objective functions were obtained for the transformation of the first seven right singular vectors. Simple Shannon type entropy functions were used in the objective functions and realistic physical constraints were imposed in the penalties. It was found that good first approximations for the pure component spectra could be obtained without the use of any a priori information. The present method out performed the two widely used routines, namely Simplisma and OPA-ALS, as well as IPCA. These results indicate that a combination of SVD, entropy minimization, and simulated annealing is a potentially powerful tool for spectral reconstructions from large real experimental systems.     

Characterization of essential oil components of Iranian geranium oil using gas chromatography-mass spectrometry combined with chemometric resolution techniques

The essential oil components of geranium oil cultivated in center of Iran were identified and determined using gas chromatography-mass spectrometry data combined with the chemometric resolution techniques. A total of 61 components accounting for 91.51% were identified using similarity searches between the mass spectra and MS database. This number was extended to 85 components using chemometric techniques. Various chemometric methods such as morphological scores, simplified Borgen method (SBM) and fixed size moving window evolving factor analysis (FSMWEFA) were used for determining the number of components, pure variables, zero concentration and selective regions. Then the overlapping peak clusters were resolved into pure chromatograms and pure mass spectra using heuristic evolving latent projections (HELP) method. A characteristic feature of the Iranian geranium oil is the absence of 10-epi-gamma-eudesmol in its constituents compared with the oil from northern and southern parts of India. The results of this work show that combination of hyphenated chromatographic methods and resolution techniques provide a complementary method for accurate analysis of essential oils.     

木香挥发性化学成分的气相色谱-质谱分析

采用水蒸气蒸馏法从木香中提取挥发油,用气相色谱-质谱联用仪对木香挥发油进行化学成分的分析。利用化学计量学方法对重叠峰进行分辨,对各个色谱峰定性,并用色谱峰总体积积分和归一化法获得各化合物的相对含量。共鉴定了60种化合物,占挥发油总成分的97%以上。其中主要有土木香内酯、巴西菊内酯、(Z)6,(Z)9-十五二烯-1-醇等。     

福州小花茉莉全花期中花源质量稳定性的研究Ⅱ．净油和头香化学成分分析

为了观察福州茉莉花源质量的稳定性,曾时其精油成分作过连续三年的成分研究￣［１］。本文继续对净油和头香成分作进一步探讨。本实验室用溶剂提取和用冷乙醇分离花蜡来获得净油．用低温吸附和溶剂洗脱获得头香样品。采用石英毛细管气相色谱（ＣＧＣ）和色谱－质谱（ＣＧＣ－ＭＳ）对成分进行剖析。实验结果对福州茉莉花源质量随气候变化的规律￣［１］作了进一步地确认。     

Self-modeling curve resolution techniques applied to comparative analysis of volatile components of Iranian saffron from different regions

Volatile components of saffron from different regions of Iran were extracted by ultrasonic-assisted solvent extraction (USE) and were analyzed by gas chromatography-mass spectrometry (GC-MS). Self-modeling curve resolution (SMCR) was proposed for resolving the co-eluted GC-MS peak clusters into pure chromatograms and mass spectra. Multivariate curve resolution-objective function minimization (MCR-FMIN) and multivariate curve resolution-alternating least square (MCR-ALS) were successfully used for this purpose. The accuracy of the qualitative and quantitative results was improved considerably using SMCR techniques. Comparison of the results of saffron from different regions of Iran showed that their volatile components are different from chemical components and relative percentages points of view. Safranal is the main component of all samples. In addition, 4-hydroxy-2,6,6-trimethyl-1-cyclohexene-1-carboxaldehyde (HTCC), 2(5H)-furanone, 2,4,4-trimethyl-3-carboxaldehyde-5-hydroxy-2,5-cyclohexadien-1-one and 2(3H)-furanone, dihydro-4-hydroxy were common in all samples with high percentages. The results proved that combining of SMCR techniques with USE-GC-MS produces a powerful tool for the analysis of the complex samples.     

Fourier transform Raman spectral measurements of powdered quaternary mixtures of organic compounds: Exceptional pure component spectral reconstruction using band-target entropy minimization (BTEM)

Fourier transform Raman spectra of eight mixtures of four organic solids, namely dicyandiamide, melamine, acetamide and urea were measured. Matrices formed from these spectra were first subjected to singular value decomposition to obtain the right singular vectors. The right singular vectors were then subjected to blind source separation using band-target entropy minimization (BTEM), thus no a priori information (i.e. involving the nature of the components present, their spectra, nor their concentrations) was included in the analysis. The recovered pure component spectra are of exceptionally high quality and are consistent with pure reference spectra. Various empirical and statistical tests, such as the Euclidean norm and target transform factor analysis, were employed to assess the quality of the recovered spectra. The present results indicate the applicability of combined Raman and BTEM analysis for solid mixtures.     

中国苦水玫瑰油香气成分的研究

 选择OV1701交联毛细管柱作为中国苦水玫瑰油的分离柱,并采用现代气相/质谱(GC/MS)、气相/红外光谱(GC/IR)技术手段,结合标准品对照,对玫瑰油中分离出的130余种化合物进行鉴别,初步鉴定出了101种化合物。研究表明,不同品种的玫瑰油形成各自不同的香味,这与栽培品种和土壤、温度、降雨量等综合栽培环境差异有关。中国苦水玫瑰油以其特有的浓郁玫瑰香气,应成为世界玫瑰油中一个重要品种。