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.     

HELP法在中草药分析中的应用研究 －冬虫夏草的化学成分测定

基于直观推导式演进特征投影(HELP)法,对冬虫夏草子座和虫体分别进行了多组分同时定性定量测定.结果表明,HELP法能减少样本提取分离的步骤,降低色谱分离条件的要求,提高检测准确度.联用色谱检测与化学计量学解析法相结合将为复杂中草药分析提供一种全新手段.     

直观推导式演进特征投影法在拖尾重叠色谱峰解析中的应用

直观推导式演进特征投影法(HELP)已成功应用于复杂体系的重叠色谱峰解析.当色谱峰拖尾时,演进特征投影图(ELPG)显示的直线段对应的区域中可能含有前面拖尾组分的信息,据此进行HELP解析可能得不到满意结果.选择ELPG上直线段的一部分,即拖尾组分末端,前面组分的信息已基本消失的区域作为选择性区域进行HELP解析.同时,提出一种新的定量方法:用主成分分析法(PCA)分解待测组分标准样品的二维数据,将得到的“标准”色谱引入HELP的定量过程,在色谱峰拖尾或解得谱峰不平滑时,得到更准确的结果.用HELP方法解析了依诺沙星、诺氟沙星和环丙沙星三组分实验体系,结果表明,加入上述措施的HELP可有效改善拖尾重叠色谱峰的解析结果.     

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.     

唇形科植物挥发油化学成分的GC/MS研究

在运用GC/MS技术的基础上采用HELP(直观推导式演进特征投影法)方法研究了九种唇形科植物的化学成分, 并以唇形科植物半枝莲为例详细介绍了HELP的解析过程. 应用总体积积分法测定各成分的相对百分含量. 鉴定出相对共有成分达70余种, 大多数为萜类化合物及其衍生物. 不同的唇形科植物的挥发油化学成分与特征成分有明显差异. 九种药材挥发性成分中均含有桉油精(Eucalyptol, 含量0.10%～1.01%)和芳樟醇(Linalool, 0.11%～3.05%). 利用GC/MS分析法结合化学计量学分辨方法鉴定挥发油化学成分, 比单独使用GC-MS法结果更准确、可靠.     

直观推导式演进特征投影法对环境样本中多环芳烃的定性定量分析

基于新近发展的直观推导式演进特征投影法(HELP), 本文提出了一个对二维数据进行同时定性定量的分析方法, 并将其成功地用于环境样本中多环芳烃化合物定量解析。对于一维色谱难以定量的重叠峰, HELP方法充分利用色谱、光谱两方面的选择性信息, 得到了具有真实物理意义的唯一解。在定性分辨结果的基础上, 本文还提出了三种可能的定量方法。这种二维数据的解析新方法, 能大幅度地降低对色谱分离条件的要求, 可直接用于复杂实际样本的定性定量分析。     

直观推导式演进特征投影法测定不同方法提取的国产血竭中龙血素B的含量

利用HPLC-DAD产生的二维数据和化学计量学方法-直观推导式演进特征投影法（HELP），解析了不同提取方法得到的国产血竭中的重叠色谱峰，并对其中的指标性成分-龙血素B进行了含量测定，结果满意。这表明这化学计量学方法与现代分析手段有机结合，将为中药等复杂体系的分析提供一条新途径。     

香港大气颗粒物中多环芳烃的 HELP 法解析

利用新近发展的直观推导式演进特征投影法(HELP),成功地对香港大气颗粒物样本中的多环芳烃化合物进行了定性定量解析.解析结果表明:在样本中存在47种化学成分,其中有18种为多环芳烃化合物及其衍生物.分辨结果与标准光谱吻合很好,并与GC-MS的定性分析结果相一致.在定性分析的基础上,还进行了定量分析.HELP方法大大降低了对色谱分离条件的要求,为今后快速、准确解析色谱光谱联用仪器产生的二维数据提供了崭新途径.     

多元曲线分辨方法和红外光谱用于奥克托今合成机理

通过红外光谱在线监测1,5-二乙酰基-3,7-二硝基-1,3,5,7-四氮杂环辛烷（简写DADN）合成奥克托今(HMX)的反应过程,利用渐进因子分析(EFA)、多元曲线分辨 交替最小二乘法(MCR-ALS)和直观推导式演进特征投影法(HELP)等化学计量学方法对反应过程获得的光谱信息进行解析,得到了各组分浓度变化曲线和对应的红外光谱,并将MCR-ALS和HELP两种方法的分析结果进行比较,得出可相互验证的一致结论,从而推测出该反应合理的反应机理。 所得结果与文献报道吻合,表明化学计量学方法结合在线红外光谱是研究奥克托今合成机理的有效手段。     

通过红外光谱结合化学计量学方法研究奥克托今的合成机理

通过红外(IR)光谱在线监测醋酐法合成奥克托今(HMX)的反应过程, 采用渐进因子分析(EFA)结合多元曲线分辨-交替最小二乘法(MCR-ALS)以及直观推导式演进特征投影法(HELP)等化学计量学方法对反应过程的光谱数据矩阵进行解析, 获得了各组分浓度变化曲线和对应的IR光谱; 并采用密度泛函理论(DFT)的B3LYP方法, 在6-31G^*基组水平上得到该化合物的全优化结构, 在振动分析的基础上求得体系的振动频率和IR光谱. 通过对比发现, MCR-ALS和HELP法可得出相互验证的一致结论; 将通过量子化学计算的中间体的IR光谱特征吸收峰与2种方法进行比较, 结果吻合, 从而推导出合理的反应机理. 实验结果表明, 化学计量学方法结合在线红外光谱是研究反应机理的有效手段, 对反应路线的选择具有指导意义.     

HELP法在中草药分析中的应用研究-冬虫夏草的化学成分测定

基于直观推导式演进特征投影（ＨＥＬＰ）法,对冬虫夏草子座和虫体分别进行了多组分同时定性定量测定．结果表明,ＨＥＬＰ法能减少样本提取分离的步骤,降低色谱分离条件的要求,提高检测准确度．联用色谱检测与化学计量学解析法相结合将为复杂中草药分析提供一种全新手段     

Analysis of PAHs in air-borne particulates in Hong Kong City by heuristic evolving latent projections

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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%.     

Essential Oil Composition of Osmanthus fragrans Varieties by GC-MS and Heuristic Evolving Latent Projections

The essential oils from two varieties of Osmanthus fragrans have been extracted by steam distillation and analyzed by gas chromatography-mass spectrometry with the help of heuristic evolving latent projections (HELP), an effective chemometric resolution method. The overlapped peak clusters were resolved into pure chromatograms and pure mass spectra with HELP. Identification of the components was by comparison of temperature-programmed retention indices (PTRIs) and by similarity searches in the National Institute of Standards and Technology mass database. Quantitative results were obtained by overall integration of the peaks. The reliability of the qualitative and quantitative results was greatly improved by using HELP and PTRIs. The main components from O. fragrans Lour. var. thunbergii Mak. (TM) and O. fragrans Lour. var. aurantiacus Mak. (AM) were 1,2-epoxy linalool and nonanal, respectively. In total, 52 volatile components in essential oil of TM and 45 in AM were analyzed qualitatively and quantitatively, accounting for 95.67 and 92.28% total contents of the essential oils.     

Resolution of multicomponent overlapped peaks A comparison of several curve resolution methods

Several curve resolution methods were compared in their performance of identification and quantification of overlapping peaks. These resolution methods are heuristic evolving latent projections (HELP), sub-window factor analysis (SFA), and orthogonal projection resolution (OPR). In this paper, HELP, SFA and OPR with the rank map produced by evolving factor analysis (EFA) or fixed size moving window-evolving factor analysis (FSMW-EFA) were applied to the simulated and experimental data. The resolved results were compared qualitatively and quantitatively. In addition, the further comparison was carried out with the results obtained from multivariate curve resolution-alternate least square (MCR-ALS) by using the initial estimates provided by EFA.     

Comparison of several curve resolution methods for drug impurity profiling using high-performance liquid chromatography with diode array detection

The performance of five curve resolution methods was compared systematically for the identification and quantification of impurities in drug impurity profiling. These methods are alternating least-squares (ALS) with either random or iterative key-set factor analysis (IKSFA) initialisation, iterative target transformation factor analysis (ITTFA), evolving factor analysis (EFA), and heuristic evolving latent projections (HELP). Real and simulated high-performance liquid chromatography diode array detection (HPLC-DAD) data were obtained for drug mixtures containing one main compound and two impurities. The elution order of the main compound and the impurities was varied. Furthermore, resolutions were varied from 0.56 to 3.36 and impurity levels from 30% down to 0.1%. For simulated data, ALS with IKSFA initialisation and HELP perform better than ITTFA and EFA, which perform better than ALS with random initialisation. ITTFA works better than EFA for almost completely separated data, while the opposite is true for moderately or strongly overlapping data. Only ALS with IKSFA initialisation and HELP were found to resolve the required 0.1% level for moderately overlapping data. For real data, comparison of the methods provides similar results. ITTFA performs clearly better than EFA. However, none of the curve resolution methods can identify or quantify impurities at the required 0.1% level. The results for real data are worse than for simulated data because of heteroscedasticity, nonlinearity, and the acquisition resolution of the A/D-converter.     

Resolution of Overlapped Capillary Electrophoresis Peaks by Using Heuristic Evolving Latent Projections to Quantify Chloroquine Phosphate and Promethazine Hydrochloride

Chloroquine phosphate and promethazine hydrochloride are two main components in compound reserpine tablets. It is difficult to separate the two compounds with capillary electrophoresis (CE). Heuristic evolving latent projections (HELP) is a chemometric algorithm which is suitable for resolving overlapped peaks from CE and HPLC. In this paper, HELP was applied to resolving the completely overlapped peaks of chloroquine phosphate and promethazine hydrochloride from CE. Mathematical separation and satisfactory quantification results can be achieved easily without too much time involved in the procedure.