流动池型微孔柱高压液相色谱与傅氏变换红外光谱联用的研究

与气相色谱不同,高压液相色谱与傅氏变换红外光谱联用时,必须考虑如何消除其流动相的强红外吸收对分析物光谱的干扰问题。消除这一干扰基本上有两种方法:即在红外检测前去除流动相的溶剂去除法和直接检测色谱流出物的光谱,然后扣除流动相干扰的流动池法。本文讨论我们发展的     

马山前胡挥发油化学成分研究

本文用毛细管气相色谱、气相色谱／质谱／计算、气相色谱／红外光谱等现代仪器分析技术，对马山前胡挥发油的化学成分进行了分析研究，从毛细管色谱分离出８０多个峰，确认了其中３７种成分，占色谱总馏出峰面积的９７％以上，该挥发油的主要化学成分为蒎烯。     

含芘苯乙烯／二乙烯苯共聚物的合成与表征

本文首次通过共聚方法和功能基化方法合成了芘标记苯乙烯／二乙烯苯共聚物，用稳态荧光光谱、裂解色谱、裂解色谱－质谱等方法对芘标记共聚物进行了详细地表征。结果表明，通过控制芘标记单体的投料或功能基化反应时间，可以将一定量的芘基标记到苯乙烯／二乙烯苯共聚物中，其荧光光谱显示了芘基的单体荧光发射和激基缔合物荧光发射；共聚物裂解色谱的甲基芘峰和苯乙烯三聚体峰反映了芘基和交联聚苯乙烯骨架的特征，据此可建立甲基芘     

倍硫磷的气相色谱/红外光谱检测

倍硫磷是我国常用农药品种，也是是 口大米的必检项目之一。本文应用气相色谱／红外光谱联用方法，探索了倍硫磷的最佳色谱条件，获得其气以谱／红外光谱图，并依靠已有的气相红外谱库进行了检索，拟建立倍硫磷的气相色谱／红外谱库，以用于农产品中该农药的GC／FTIR监控。     

裂解气相色谱—红外光谱联用分析聚合物结构（II）

采用国产ＳＣ－７型色谱以及ＪＰ－０１型居里点裂解器，Ｎｉｃｏｌｅｔ１７０ＳＸ红外光谱仪及接口组成的裂解色相色谱－傅里叶变换红外光谱（ＰＧＣ／ＦＴＩＲ）分析仪，ＨＰ－１７型大口径毛细管色谱柱，分析了两个复杂组成的聚合物样品。从主要裂解碎片峰的定性结果及形成机理出发，逐步推出了原样品的组成和结构，常规红外光谱分析方法被用来作为对比，但它获得的信息有限，无法得到能与ＰＷＢＣＧＣ／ＦＴＩＲ分析结果和媲美的     

比光谱-导数-紫外分光光度法同时测定水中硝酸根和亚硝酸根

利用二元混合物的混合光谱与其中某一组分光谱的比值对波长求导，可达到分辨重叠光谱的目的。本文研究了用比光谱-导数-紫外分光光度法同时测定水样中NO3-和NO2-，以“减法技术”求导，兼具导数光度法能消除低频背景和高频噪声干扰及线性回归法分辨能力强的优点。方法避免了一般光度法需加入试剂而可能引起的误差。在pH7～9条件下测量203um～219um的光吸收值，用比光谱-导数技术处理，同时测定合成试样中0～4mg／L的NO3-和NO2-，6次测定相对标准偏差＜7％，加入回收率在95％～101％之间。讨论了干扰离子的影响及消除，并与P-矩阵法作了比较。方法已用于井水、雨水及湖水中NO3-和NO2-的同时测定。     

化学计量学用于决明子色谱指纹图谱峰纯度的鉴别

应用化学计量学方法鉴别色谱指纹图谱的峰纯度。对背景进行扣除后,用对照组分光谱构建正交投影矩阵对目标色谱峰的光谱进行投影,以目标色谱峰投影后的残余光谱与投影前的原始光谱的夹角余弦为判据鉴别目标色谱峰的峰纯度：用该方法对决明子药材色谱指纹图谱的峰纯度进行识别,鉴别出大黄素、大黄酚和大黄素甲醚三个纯色谱峰。此方法用于色谱指纹图谱峰纯度的鉴别,结果可靠。     

芳香烃异构体的毛细管柱气相色谱—傅里叶变换红外光谱联用技术分析

采用国产色谱仪与进口红外光谱仪及接口组成的气相色谱－傅里叶变换红外光谱（ＧＣ／ＦＴＩＲ）分析仪，使用大口径毛细管柱，分析了乙苯与苯乙烯固相催化反应液的复杂芳香烃异构体组成，讨论了ＧＣ／ＦＴＩＲ分析中随机噪声和基线漂的去除方法。采用等高线图９ＣＴＤ）分析技术得混合液中各组分的纯气相红外光谱图，最后了１４个气相色谱峰中的９个，占整个色谱峰面积９９５以上。     

裂解毛细管柱气相色谱－傅里叶变换红外光谱的剖析应用

采用裂解气相色谱－傅里叶变换红外光谱（ＰｙＧＣ／ＦＴＩＲ）技术，使用大口径毛细管柱，分析了一未知进口涂料，对其主要裂解碎片峰进行了定性，进而从特征碎片的产生推出该涂料的成分。并同常规红外光谱差减法进行了比较，结果表明ＰｙＧＣ／ＦＴＩＲ具有简便、快速、全面和无需标样等优点，有广泛的应用价值。     

裂解气相色谱－红外光谱联用分析聚合物结构（Ⅱ）

采用国产ＳＣ－７型色谱仪及ＪＰ－０１型居里点裂解器、Ｎｉｃｏｌｅｔ１７０ＳＸ红外光谱仪及接口组成的裂解气相色谱－傅里叶变换红外光谱（ＰＧＣ／ＦＴＩＲ）分析仪、ＨＰ－１７型大口径毛细管色谱柱，分析了两个复杂组成的聚合物样品。从主要裂解碎片峰的定性结果及形成机理出发，逐步推出了原样品的组成和结构。常规红外光谱分析方法被用来作为对比，但它获得的信息有限，无法得到能与ＰＷＢＣＧＣ／ＦＴＩＲ分析结果相媲美的结论，充分显示了ＰＷＢＣＧＣ／ＦＴＩＲ用于聚合物分析的优越性。     

Effect of local background intensities in the normalization of cDNA microarray data with a skewed expression profiles

Normalization of the data of cDNA microarray is an obligatory step during microarray experiments due to the relatively frequent non-specific errors. Generally, normalization of microarray data is based on the null hypothesis and variance model. In the Yang's model (Yang et al., 2001), at least two types of noises are included. The one is additive noise and the other is multiplicative noise. Usually, background is considered as one of additive noise to the signal and the variation between the signal pixels is the representative multiplicative noise. In this study, the relation between the signal (spot intensity minus background intensity) and background was observed and the influence of background on normalization as a representative additive factor was investigated. Although the relation has not been considered as a factor affecting the normalization, it could improve the accuracy of microarray data when the normalization was carried out considering signal/background ratio. The background dependent normalization decreased the number of genes whose expression levels were changed significantly and it could make their distribution more consistent through the whole range of signal intensities. In this study, printing pin dependent normalization was also carried out regarding the printing pin as a representative multiplicative noise. It improved the distribution of spots in the Cy3-Cy5 scatter plot, but its effect was slight. These studies suggest that there are some influences of the signals on the local backgrounds and they must be considered for the normalization of cDNA microarray data.     

Trilinear decomposition method applied to removal of three-dimensional background drift in comprehensive two-dimensional separation data

A novel technique for removal of three-dimensional background drift in comprehensive two-dimensional (2D) liquid chromatography coupled with diode array detection (LCxLC-DAD) data is proposed. The basic idea is to perform trilinear decomposition on the instrumental response data, which is based on the alternating trilinear decomposition (ATLD) algorithm. In model construction, the background drift is modeled as one component or factor as well as the analytes of interest, hence, the drift is explicitly included into the calibration. The method involves performing trilinear decomposition on the raw data, then extracting the background component and subtracting this background data from the raw data, leaving the analytes' signal on a flat baseline. Simultaneous evaluation of three-dimensional background drift and true signals may improve the quality of the data. This method is applied to the determination and removal of three-dimensional background drifts in simulated multidimensional data as well as experimental comprehensive two-dimensional liquid chromatographic data. It is shown that this technique yield a good removal of background drift, without the need to perform a blank chromatographic run, and required no prior knowledge about the sample composition.     

Ionic strength dependence of formation constants-X: proton activity coefficients at various temperatures and ionic strengths and their use in the study of complex equilibria

The activity coefficients of the proton were determined in aqueous solution in the presence of several background electrolytes at 10, 25, 37 and 45 degrees and 0.01 < or = I < or = 1M. The results indicate that the proton activity coefficients are fairly independent of the different salts used as background, in particular when ion-pair formation between cations and anions of the medium is taken into account. This result is in agreement with the findings of previous works in this series. Some previously published data were reanalysed for comparison, and showed excellent accordance with the present results. A general equation for calculating proton activity coefficients is reported.     

Control samples for the determination of pH in low ionic strength waters: consensus values from interlaboratory tests

The results of a series of interlaboratory tests using low ionic strength buffer solutions are reported. The test data and other background information are presented as the basis for more realistic quality control materials for pH determination in low ionic strength waters. The effect of atmospheric carbon dioxide on the pH of low ionic strength reference samples is discussed. Several control samples are recommended for routine use.     

GammaLab: a suite of programs for k0-NAA and gamma-ray spectrum analysis

The GammaLab is a collection of computer codes, written in MATLAB, for performing calculations involved in k ₀ neutron activation analysis. The main features of the program include calibrations including energy-channel, energy-FWHM and energy-efficiency for different geometries, background subtraction, nuclide identification, spectral interference correction, elemental concentration and limit of detection determination. The data input is taken from two files one is the spectrum file stored in IAEA ASCII format and other is report file containing peak energy and peak area data. The information about sample, irradiation and counting conditions, background spectra are retrieved from QAQCData database. GammaLab takes nuclear data such as gamma lines, emission probabilities, half-lives, and k ₀ factors from NucData database. The sample results which contain elemental concentrations with uncertainties are stored in the QAQCData database. The program has been evaluated by analyzing several hundred spectra and results were found satisfactory.     

Silver cluster interferences in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry of nonpolar polymers

Potential difficulties associated with background silver salt clusters during matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) of nonpolar polymers are reported. Silver salt cluster ions were observed from m/z 1500 to 7000 when acidic, polar matrices, such as 2,5-dihydroxybenzoic acid (DHB), all-trans-retinoic acid (RTA) or 2-(4-hydroxyphenylazo)benzoic acid (HABA), were used for the analysis of nonpolar polymers. These background signals could be greatly reduced or eliminated by the use of nonpolar matrices such as anthracene or pyrene. Representative examples of these background interferences are demonstrated during the analysis of low molecular weight nonpolar polymers including polybutadiene and polystyrene. Nonpolar polymers analyzed with acidic, polar matrices (e.g., RTA) and silver cationization reagents can yield lower quality mass spectral results when interferences due to silver clusters are present. Replacing the polar matrices with nonpolar matrices or the silver salts with copper salts substantially improved the quality of the analytical results. In addition, it was found that silver contamination cannot be completely removed from standard stainless steel sample plates, although the presence of silver contamination was greatly reduced after thorough cleaning of the sample plate with aluminum oxide grit. Carry-over silver may cationize polymer samples and complicate the interpretation of data obtained using nonpolar matrices in the absence of added cationization reagents.     

Intensity modulation of the Shirley background of the Cr 3p spectra with photon energies around the Cr 2p edge

The background in X‐ray photoelectron spectroscopy data originates, partially, from inelastically scattered photoelectrons. In fact, the current theoretical methods for calculating the background intensity are based on electron energy losses. However, a critical part of the experimental signal, which is known as the Shirley background, cannot be described within the current formalisms. This suggests that the Shirley electrons are not associated with energy losses of photoelectrons and must originate from a different photoexcitation phenomenon with a cross section of its own. We propose a mechanism based on core channeling as the physical origin of the Shirley signal.     

Microarray data classification using inductive logic programming and gene ontology background information

There exists many databases containing information on genes that are useful for background information in machine learning analysis of microarray data. The gene ontology and gene ontology annotation projects are among the most comprehensive of these. We demonstrate how inductive logic programming (ILP) can be used to build classification rules for microarray data which naturally incorporates the gene ontology and annotations to it as background knowledge without removing the inherent graph structure of the ontology. The ILP rules generated are parsimonious and easy to interpret. Copyright © 2010 John Wiley & Sons, Ltd.     

用遗传算法优化的约束背景双线性化方法处理含未知背景组分干扰的色谱二维谱图体系

数值遗传算法是全局优化方法, 本文将其引入约束背景双线性化问题的优化求解过程, 以避免陷入局部最优。用本方法处理了模拟数据和两个实际含未知背景干扰的色谱二维谱图体系, 并探讨了如何提高遗传算法在优化平台区域的寻优速度,结果令人满意。     

Computerized detection and evaluation of peaks in survey spectra from photoelectron spectroscopy

The computer program described is written in Algol-60 and allows a fast data analysis of photoelectron peaks in survey spectra (0–1500 eV). Additional peak parameters such as area, background and peak width are also determined. The assumptions about peak shape are kept to a minimum. In spectra with good counting statistics, it is possible to detect peaks with peak/background ratio down to 0.01.