小波变换作为预处理的多元线性回归法

多元线性回归法是一种应用非常广泛的多变量分析方法，用于多组分同时定量分析。然而，噪声的存在影响了多元线性回归法分析的准确度。近年来小波变换以其多分辨率分析的特性、方法简单、快速等优点成为一种有效的去除分析信号噪声的方法。本实验就噪声对多元线性回归法的影响以及小波变换与多元线性回归法结合提高多元线性回归法分析准确性的有效性进行了研究。     

毛细管电泳激光诱导荧光检测信号的小波滤噪

采用小波滤噪方法对毛细管电泳激光诱导荧光检测信号进行了处理，研究了小波变换中小波基的选择及噪声阈值的选择对滤噪的影响。结果表明，采用DB4小波基能有效消除毛细管电泳激光诱导荧光检测信号中存在的噪声，使信噪比得到较大改善。     

一种基于二进小波变换的自适应滤波方法

根据信号和噪声经小波变换后在不同尺度上有不同的特征，将相邻尺度二进小波变换值的相关量进行归一化处理并与小波变换值比较来判断信号与噪声，以噪声在各尺度的方差作为终止迭代的标准，提出了一种基于二进小波变换小波域选择噪声的自适应滤波方法。研究了模拟信号的去噪过程、半峰宽和信噪比对去噪结果的影响，并对模拟含噪信号和含噪毛细管电泳信号去噪前后的结果进行了比较。实验结果表明：由于该方法具有良好的自适应性和显著的滤波效果，必将得到广泛的应用。     

一种新的小波滤波方法在化学谱图信号滤噪中的应用

仪器分析测定中，噪声的存在往往影响分析的准确度和仪器的检出限。小波变换多分辨分析的特性使得它成为一种很好的滤噪方法。基于小波分解后信号与噪声的小波系数随尺度变化规律不同的特性，提出了一种新的滤波滤方法-空域相关法，即通过不同尺度上相关系数模值与小波系数模模值的比较，达到滤波滤的目的。本文提出的方法具有无需人为选定无需人为选定滤噪阈值和小波函数、方法简单、失真度小等优点，可以大在提高信号的信噪比。模拟数据和ICP-AES实验数据证明了该方法的有效性。     

利用小波变换检测电化学噪声信号波形

简述了应用小波变换检测点蚀电化学噪声信号的基本原理,对在3.5％ NaCl溶液中工业纯铝发生点蚀的电化学噪声信号检测分析表明：小波变换能够提取发生点蚀的电化学噪声信号和测量系统噪声在多惊讶分辨空间中的波形特征,根据表征该特征的小波系数模极大值在不同尺度下的传播特性,可实现对点蚀电化学噪声信号波形的检测。     

连续样条小波变换用于分解重叠峰的研究

以B-样条小波为分析小波，提出了用于分析化学重叠信号解析的新方法——连续样条小波变换，结果表明：连续样条小波变换应用于分析化学信号的处理，能使峰变窄同时还能提高信号的信噪比，是一种新型有效的重叠信号解析方法，能从含噪声重叠信号中直接得到重叠峰的峰数目及其相应的峰位置。     

基于提升格式的小波变换用于处理化学信号

将提升haar小波变换应用于对不同类型含高噪声化学信号的处理,提出1种用于高噪声化学信号中滤除噪声的快速新方法——提升小波滤噪法,并使之与重叠峰分辨技术联用;以优选的小波分解层数对低信噪比的分析化学信号进行基于提升格式的小波变换处理,取得满意的结果;方法简单、快捷、准确、易行．运算速度是传统小波变换的一半,对高噪声化学信号的处理结果信噪比提高几百倍,峰位置相对误差小于1．5％;应用于氨基酸体系毛细管电泳检测信号的处理,有效降低了实验噪声的影响,分辨提取了难以察觉的信号．结果峰形变窄,峰高增加．大大提高了峰的分辨率．验证和显示了方法的可行性和优越性。     

二维小波变换与子窗口因子分析法结合用于含噪声HPLC-DAD数据的解析

将二维小波变换与子窗口因子分析法相结合,用于模拟的高噪声HPLC-DAD数据的解析.首先应用二维小波变换滤除噪声,然后采用子窗口因子分析法解析重叠峰.结果表明,信噪比为10的高噪声基本被滤除掉.     

二进小波变换极大模法用于分析化学信号的滤噪

实验数据的滤噪在分析化学领域中具有重要的意义。小波变换技术具有很强的信号分离能力，容易把随机噪声从信号中分离出来，从而提高信号的信噪比。本文使用滤噪方法不同于传统离散小波变换方法，而是通过引入二进小波变换和李氏指数的概念，根据噪声与有用信号的极大模截然不同的特征，实现信号滤噪。实验数据的仿真结果研究也证明该方法的可行性。     

同时测定铁钴铜的小波软阈值核心偏最小二乘法

提出了一种小波软阈值核心偏最小二乘法，同时测定铁、钴、铜；该法结合小波软阈值法和主组分分析改进除噪声质量，与其它软阈值法比较选用了HYBRID法；通过最佳化，小波函数和低频截止收缩水平（L）分别选用Symmlet6和2；设计了一个名为软阈值小波核心偏最小二乘法（STWKPLS）的程序进行全部计算，实验结果表明该法是成功的，并且优于核心偏最小二乘法。     

红外光谱定量分析中标准添加法的新计算方法

对红外光谱定量分析中的标准添加法进行了误差分析,提出了一种新的数学处理方法,使标准添加法的误差大为降低,准确度得到提高。用简单的苯－氯仿二元体系对此法进行了验证。     

Quality evaluation of moluodan concentrated pill using high‐performance liquid chromatography fingerprinting coupled with chemometrics

In this study, a fast and effective high‐performance liquid chromatography method was developed to obtain a fingerprint chromatogram and quantitative analysis simultaneously of four indexes including gallic acid, chlorogenic acid, albiflorin and paeoniflorin of the traditional Chinese medicine Moluodan Concentrated Pill. The method was performed by using a Waters X‐bridge C₁₈ reversed phase column on an Agilent 1200S high‐performance liquid chromatography system coupled with diode array detection. The mobile phase of the high‐performance liquid chromatography method was composed of 20 mmol/L phosphate solution and acetonitrile with a 1 mL/min eluent velocity, under a detection temperature of 30°C and a UV detection wavelength of 254 nm. After the methodology validation, 16 batches of Moluodan Concentrated Pill were analyzed by this high‐performance liquid chromatography method and both qualitative and quantitative evaluation results were achieved by similarity analysis, principal component analysis and hierarchical cluster analysis. The results of these three chemometrics were in good agreement and all indicated that batch 10 and batch 16 showed significant differences with the other 14 batches. This suggested that the developed high‐performance liquid chromatography method could be applied in the quality evaluation of Moluodan Concentrated Pill.     

一种基于光谱分析的二元不完全重叠色谱峰的分离解析方法

基于二极管阵列检测器获得的色谱-光谱数据,建立了一种二元不完全重叠液相色谱峰的解析方法: 色谱数据经过去噪、归一化处理后,计算各时间点的光谱差异并进行系统聚类分析,提取特征光谱后,利用非负最小二乘法对色谱-光谱矩阵进行解析,得到基于特征光谱的流出曲线,进而得到分离后的色谱峰。将解析结果和纯标样的色谱峰进行比较,解析后的光谱图和纯标样的光谱图无显著差异,保留时间相差小于0.01 min。实验结果表明,该方法在二元不完全重叠液相色谱峰的解析方面能取得良好的效果。     

超快速液相色谱法测定甲基苯丙胺

建立了用超快速液相色谱(UFLC)仪测定甲基苯丙胺含量的方法。采用XR-ODS柱,流动相为0.05%磷酸-甲醇(85∶15),流速为0.4 mL/min,检测波长为215 nm。该法在1~5000μg/mL浓度范围内线性关系良好,r2=0.9998,日内与日间保留时间和峰面积的相对标准偏差均小于6%,样品的加标回收率为92.4%~116.7%,检出限为0.68μg/mL。该方法适用于甲基苯丙胺的定性定量分析。     

主成分分析在近红外定量分析校正集样本优选中的应用

将主成分分析方法用于近红外定量分析校正集样本的优选,提出一种根据样本光谱第一主成分得分优选校正集样本的方法,并使用本方法从418个烟草样本中优选得到约105个样本的校正集。通过对烟碱成分实际建模与外部验证,与随机法、含量梯度法两种校正集样本挑选方法的性能进行了对比。结果表明,本方法既克服了随机法挑选样本代表性不足的风险,又可避免含量梯度法必须测定所有样本成分含量而造成的人力物力消耗,具有无需编程、操作简单、易于推广的特点。     

Multidetermination of PCBs and pesticides by use of a dual GC column-dual detector system

Summary A new gas chromatographic method involving the use of two capillary columns, a switching valvue and electron capture-nitrogen-phosphorus detection, and allowing up to four retention characteristics per component to be obtained is reported.The proposed method was applied to the analysis for 123 compounds (13 PCBs and 110 pesticides), the determination limits and optimal measuring ranges of which are reported.The performance of the method was checked by analysis of certified standards and spiked samples, and was applied to the determination of the analytes in various water samples.     

Extraction of maleic hydrazide residues from potato crisps and their determination using high-performance liquid chromatography with UV and atmospheric pressure chemical ionisation mass spectrometric detection

A method was required for the determination of maleic hydrazide residues in potato crisps. A published method for the extraction of the analyte from onions and potatoes was evaluated and found to be inappropriate due to the inability of the extracting solvent to penetrate the oily matrix. A method was developed to overcome this problem; the resulting recovery data (mean=92.9%. R.S.D.=8.3%, N=16) confirmed its efficiency, and was used to analyse 48 retail potato crisp samples. To confirm possible residues identified by screening with HPLC-UV, and HPLC-atmospheric pressure chemical ionization MS method was developed. There was good agreement between the data obtained from the detection techniques (R²=0.978, slope=1.11).     

Inexpensive FIA method to determine trace levels of imazapyr by UV-detection enhanced with electrochemical polarization

A new flow injection analysis method with spectro-electrochemical detection (FIA/SEC) to determine trace levels of imazapyr on water samples is presented. The non-chromatographic method involves the use of a bench photometer, a single-potential potentiostat, a low pressure pumping system and a home-made spectro-electrochemical flow detector (SEC-FD), specifically adapted for the described method and using a stainless steel/electrolytic lead/lead chloride (SS/e-Pb/PbCl₂) working electrode. The limit of quantification (LOQ) reached for the optimized work parameters was 0.02 µg/mL, the relative standard deviation (RSD) in the whole range of linear response was less than 2% and a wide linear response range from 0.005 to 6.0 µg/mL was obtained. A standard addition method was used to determine the imazapyr amount in natural waters containing commercial formulation of such herbicide, the Recovery % has values close to 105%. The method performance makes it suitable to analyze the legal imazapyr tolerances established by the U.S. EPA avoiding the use of expensive chromatographic equipments and/or complicated sample preparations.     

Detailed hydrocarbon analysis of gasoline by GC-MS (SI-PIONA)

A gas chromatographic – mass spectrometric (GC-MS) method has been developed for detailed analysis of the hydrocarbon content of gasoline. The method is equipped with special software and includes the analysis of oxygenated compounds in a single run. The technique utilizes three basic components: the separating power of high resolution capillary gas chromatography, a mass spectrometer with a controllable ion source and ion fragmentation ratios, and unique software for data handling and preparation of reports. The C₄ to C₁₂ range of hydrocarbons in gasoline is covered by the method. A sample of unleaded gasoline from a gas station was analyzed without sample preparation. The results are discussed.     

同步热分析技术在煤炭品质评价和分类鉴别的应用研究

采用经典法(GB/T 212-2008)、常量热重法(Marco-TG)和同步热分析三种方法分析了多种产地的煤炭产品,结果表明,在煤炭样品制备良好的条件下,常量热分析法与经典法的煤炭工业分析值基本吻合,同步热分析(STA)法的结果波动相对较大,可作为半定量的快速评价煤炭品质检测方法;根据褐煤、烟煤和无烟煤燃烧时的差示扫描量热曲线热力学特征,初步探讨了三种煤炭的分类鉴别技术,促进煤炭产品的进出口贸易。