气相色谱全流出曲线的曲线拟合法及其应用

本文论述了人工智能气相色谱软件之一——曲线拟合法谱图解析程序ChgrA-84的基本原理和数学模型及其部分应用。“高斯函数的指数衰减修正函数”(EMG)作为数学模型可以通过计算机编程,很好地描述一个气相色谱的拖尾峰峰形曲线。对EMG模型参数τ,σ在不同温度不同样品组份的系统考察,得到了τ和σ与保留时间t_r之间的近似线性规律。在这基础上建立的曲线拟合法可以通过计算机的软件形式再现不同温度的模拟色谱图,并可对一定范围的重叠峰做面积定量测定。     

定量解析程序升温脱附谱图的新方法

能量分布不均匀表面的TPD谱图,常常出现拖尾、峰重叠等复杂情况,难以定量解析。本文提出的T_f法,解决了这类TPD谱图的覆盖度θ的求值问题。并以CO,CO,H_2在Cu/ZnO/Al_2O_3型低变催化剂上的TPD谱图为例,证明了T_f法在实际应用中的可行性和可靠性。     

基于多级质谱的蛋白质组定量新方法新技术进展

定量蛋白质组学已经成为蛋白质组学的一个重要分支,以生物质谱为核心的定量蛋白质组方法日益发展。按照定量所依据的质谱信号来源于一级质谱谱图还是多级质谱谱图可以将定量蛋白质组方法分为一级质谱定量和多级质谱定量。本文主要综述基于多级质谱的定量方法和技术进展,分析比较了这些方法的优缺点,并对基于多级质谱的定量方法发展进行了展望。     

模糊聚类分析评价炭纤维裂解色谱图重现性

利用模糊聚类分析评价了炭纤维表面裂解色谱图的重现性。结果表明,模糊聚类分析可以综合评价谱图重现性,从而为定量计算中谱图的选取提供依据。     

卡尔曼滤波辅助色谱分析法的研究与应用Ⅰ．色谱重叠峰的分辨

色谱方法系广泛应用于分析化学、生物医学、环境科学等领域中重要而有效的工具。在进行结构及性质极为相近的物质分离分析时,常遇到谱图重叠的现象。为解决诸类问题,采用垂线法、切线法等进行色谱定量较为简便直观,仅对     

单纯形加速法解析TPD谱图

以Polangi—Wagner模型为基础、谱峰高的方差为目标函数,用单纯形加速法对TPD谱图进行定量解析,求算脱附活化能和指前因子,计算值与理论值一致,对重叠峰的解析结果更为理想.     

非对称色谱峰的拟合与重叠峰的拟合解析

 ]利用色谱保留时间tR与色谱峰形模型参数tG、σ、τ间的线性关系、预测了气相色谱填充柱上非对称的和重迭的色谱峰的有关参数，并据此对这两类色谱峰进行了拟合和解析。与常用重叠峰解析方法如中垂线法，三角形法和切线法解析结果的对比证明，曲线拟合法在这些方法中具有最好的准确度。用曲线拟合法进行实际定量的结果表明，对于非对称峰，其定量的相对误差小于0.5％，而对于重叠峰的定量误差则在10％以内。     

X射线衍射多谱峰匹配强度比定量相分析方法

提出了1种采用x射线衍射多谱峰匹配强度比进行定量相分析的新方法;该法是利用混合物样品x射线衍射谱图中的多谱峰数据,结合ICDD卡中的各相标准谱峰的相对强度分布数据进行最小二乘法回归分析,求得混合物样品中各相间的多谱峰匹配强度比;以多谱峰匹配强度比取代通常采用的特定单一谱线强度比,用于混合物样品的x射线衍射定量相分析,有利于提高定量相分析的精度;采用多谱峰匹配强度比结合绝热法和基体清洗法X射线衍射定量相分析原理,通过对4组分混合物样品的分析,证实实验结果和理论完全一致。     

Zeeman效应AAS中元素的吸收线分裂行为的研究

本课题包括三方面内容: 1.绘制了周期系Ⅰ-Ⅷ族元素吸收线的Zeeman分裂谱图,以往文献只见过51条线15幅图,稀土元素zeeman谱图是空白。本工作列出包括稀土元素在内的250条线97幅Zeeman图。结合谱图对灵敏度的影响的统计趋势的实验研究,第一次给商品ZAAS使用者提供系统、完整有半定量概念的Zeeman谱图。     

毛细管区带电泳测定纳米粒子粒度分布的研究

建立了一种用毛细管区带电泳测定纳米粒子平均粒径及粒径分布的新方法。该方法通过外标定量法对样品的原始电泳谱图进行定量校正,从而得到样品的粒径分布图及平均粒径。外标定量法包括迁移时间-粒径校正曲线的建立及不同粒径含量校正曲线的建立。该方法所需样品量少,且粒度分布结果具有统计代表性。     

Peak area measurement of severely overlapped pairs

Summary Based on the ratio of two apparent heights and an empirical correction factor, a method is presented for quantitation of peak areas of severely overlapped pairs. This method can be applied to a wide range of area ratios and peak asymmetries, provided there exists a clear and precise valley-except for shoulder peaks. The relative errors of the first peak are usually within ±3% and theoretical relative error limits are −7.0% to +5.5%. Peak asymmetry of a severely overlapped pair can be determined using the ratio of the front half-width to the rear half-width at 10% peak height of an overlapping profile. The asymmetry so determined is an apparent one and the relative errors are −4% to +5.3% for peaks with 90% relative valley, depending on area ratio, degree of overlap and asymmetry. An empirical area equation for the first peak involving area ratio, asymmetry, resolution and the area measured by a perpendicular drop algorithm is also developed.     

Analysis of enantiomers giving partially overlapped peaks by using different treatments of the chromatographic ultraviolet signals: quantification of pseudoephedrine enantiomers

Different strategies for the quantification of partially coeluting optical isomers have been investigated. The methods tested are based on the use of different features as the analytical UV signals: peak heights, perpendicular drop areas, first and second derivatives of the chromatograms, peak areas obtained by deconvolution of the overlapped peaks with data fitting optimization, and a multivariate model (principal component regression, PCR). The amphetamine-derivative drug pseudoephedrine was selected as a model compound. For chromatography, LiChrospher 100 RP₁₈ and a mobile-phase consisting of methanol and a solution of carboxymethyl-β-cyclodextrin (the chiral selector) were used. The UV detector was set at 215 nm. The accuracy obtained with the tested methods at different degrees of overlapping and at different concentration ratios between enantiomers was evaluated. The results of this study demonstrated that the best option for quantification of partially overlapped UV peaks of enantiomers and to obtain the enatiomeric excess is the use of a PCR model using peak heights, perpendicular drop peak areas and deconvoluted peak areas as the original variables. The predictive ability of the proposed calibration model is of about 2–8 times better (depending on the overlapping degree) than that achieved with the other models tested.     

Correction method for quantitative area determination of overlapping chromatographic peaks based on the exponentially modified Gaussian (EMG) model

A simple method is presented for peak area correction of overlapping peaks. This correction is necessary for the normal approach of dealing with overlapping peaks by a vertical line at the valley point. The relative area errors caused by this vertical line are calculated as the correction factors in three dimensions of peak separation, peak ratio, and peak tailing skew. The calculation is based on the exponentially modified Gaussian asymmetric peak model.     

Study on Separation Method of Overlapped Peaks in Differential Thermal Analysis with Computer Simulation

With the computer simulations, it has been found that in Differential Thermal Analysis (DTA) the overlapped peaks do not satisfy the linear overlapping principle, and the relationship between the overlapped peaks is rather complex that is a function of sample thermal conductivity, specific heat, quantity and latent heats, etc. If the first point where the two peaks begin to overlap is at the posterior half of the first peak curve and the two overlapped peaks can be identified by two different peaks, from the curve of overlapped peaks we can know that the temperature corresponding to the first point deviating from the sample's first phase change curve is the sample's second phase change temperature. This revised version was published online in August 2006 with corrections to the Cover Date.     

Chromatographic peak deconvolution of constitutional isomers by multiple-reaction-monitoring mass spectrometry

Highly efficient and sophisticated separation techniques are available to analyze complex compound mixtures with superior sensitivities and selectivities often enhanced by a 2nd dimension, e.g. a separation technique or spectroscopic and spectrometric techniques. For enantioselective separations numerous chiral stationary phases (CSPs) exist to cover a broad range of chiral compounds. Despite these advances enantioselective separations can become very challenging for mixtures of stereolabile constitutional isomers, because the on-column interconversion can lead to completely overlapping peak profiles. Typically, multidimensional separation techniques, e.g. multidimensional GC (MDGC), using an achiral 1st separation dimension and transferring selected analytes to a chiral 2nd separation are the method of choice to approach such problems. However, this procedure is very time consuming and only predefined sections of peaks can be transferred by column switching to the second dimension. Here we demonstrate for stereolabile 1,2-dialkylated diaziridines a technique to experimentally deconvolute overlapping gas chromatographic elution profiles of constitutional isomers based on multiple-reaction-monitoring MS (MRM-MS). The here presented technique takes advantage of different fragmentation probabilities and pathways to isolate the elution profile of configurational isomers.     

分解色谱重叠峰的参数契合法

本文研究了色谱重叠峰一阶导数曲线中各极值点的相对位置与重叠子峰面积比之间的关系，提出了一种模式参数契合的色谱重叠峰分解方法，它在准确性方面优于传统的垂线法，在速度方面优于模型拟合法，可用于实时快速处理。     

分辨伏安分析重叠峰的研究

研究了一种处理伏安(极谱)重叠峰的数学模型。将几类具峰状的极谱电流公式归纳成一般的关系式,提出了一个通用的拟合函数,经非线性最小二乘法处理,可得到重叠组份的蜂高、峰电位和半峰宽等参数。本法适用于示差脉冲极谱、交流极谱、方波极谱、一阶导数卷积伏安法及其反向溶出伏安重叠峰的分离。已用于示差脉冲极谱和交流极谱重叠峰的分辨,得到满意结果。     

Spline wavelet in the resolution of overlapping voltammetric peaks

Spline wavelet transform is used to resolve overlapping voltammetric peaks. A suitable resolving factor is chosen to multiply the filters of spline wavelet and make it a peak resoluter. Simulated overlapping voltammetric peaks are processed by the peak resoluter and satisfactory results are obtained. Base-line separation can be achieved, the relative errors of peak position are less than 3.0%, and the relative errors of peak area are less than 5.0%. The effect of different resolving factors and spline wavelet basis are discussed. To test the procedure, two systems, cadmium (Ⅱ)-indium (Ⅲ) and lead (Ⅱ)-thallium (Ⅰ), are used.     

Analysis of peak asymmetry in chromatography

The knowledge of the symmetry of chromatographic peaks is extremely important regarding the digital signal processing. The significant deviation of the peak shape from the symmetrical peak makes hardly possible the acquisition of chromatographic signal information, such as the retention time, the peak area, the peak width at half peak height, the peak overlapping, etc. In the literature one can find many methods for the determination of the asymmetry factor. For example it is suitable to calculate the skewness from the third central moment. However in case of noisy baseline the value of the skewness oscillates highly depending on the number of points used for the mathematical calculation. In this work a new method is presented for the determination peak shape asymmetry. We order mathematical function to the chromatographic peaks by fitting, and then symmetrical curve is generated with the same peak maximum position and height, the peak width is fitted. The difference of the two functions is constituted and areas of the data differences are calculated, which are really characteristics of the peak asymmetry. Correlation between the area of the difference signal and the asymmetry factor is established. The method was applied for different types of chromatographic peak shapes and the results were interpreted.     

DSC examination of alloys

The formation and thermal dissolution of dispersed particles was studied in aluminium alloys. It was found that only high heating rates (80°C min⁻¹) could provide DSC curves characteristic of the phase structure of the samples. The kinetic evaluation of the DSC curves was carried out by least squares curve fitting. In this way reasonable kinetic parameters and reliable peak resolution could be obtained for the overlapping peaks.