多组分体系的同时分光光度测定——非线性方程组法

分光光度法与计算数学结合同时直接测定多组分体系已有多种方法,其中以经典方程组法,最小二乘法等应用较多^[1],这些方法一般将吸光度与浓度之间的关系看作线性,且假设吸光度具有加和性.     

线性最小二乘法在环境空气检测领域能力验证结果评价中的应用

对线性最小二乘法在环境空气检测领域能力验证结果统计评价的应用开展了研究,并比较了线性最小二乘法与En值法的评价结果。研究结果表明,最小二乘法和En值法得出的评价结果相似。最小二乘法能够对能力验证数据统计结果进行有效的评价,并可以减少因实验室不能正确评估测量不确定度对结果评价的影响。     

模糊聚类—催最小二乘回归光度法同时测定地质样品中金铂钯铑的研究

将模糊聚类分析与偏最小二乘法相结合,对地质样品中吸收光谱严重重叠的贵金属多组分体系进行解析,较好地解决了计算光度分析中校准模型的优化问题,使计算结果的精度得到了显著提高,分析结果的相对误差小于１０％,标准偏差小于０．６７,明显优于一般偏最小二乘（ＰＬＳ）法。采用小铳试金法消除样品中贱金属元素的干扰,其回收率为９２％￣１０７％,标准偏差为０．１０￣０．６７;相对标准偏差为４．７％￣１１．０％,并对影     

组合区间偏最小二乘法结合红外光谱法测定在用润滑油的运动粘度

采用组合区间偏最小二乘法结合红外光谱法快速测定在用润滑油的运动粘度。采用组合区间偏最小二乘法高效提取与粘度变化相关的光谱信息,提高粘度校正模型的测量精度。在设置4 000~400cm-1范围的区间数为12时,选择2,10,11,12等4个子区间,对应的光谱区域为1 300~400cm-1、3 700~3 400cm-1,模型校正偏差达到0.031 5。对模型预测精度的验证结果说明本法与运动粘度标准方法之间具有很好的相关性,模型可以用于定量分析在用润滑油在40℃时运动粘度值。     

循环子空间回归的一种快速算法及其在定量构效关系中的应用

循环子空间回归（ＣＳＲ）通过改变解空间的维数,可以获取一系列的回归模型,其中包括最小二乘回归（ＬＳＲ）、主成分回归（ＰＣＲ）、偏最小二乘回归（ＰＬＳＲ）和许多中间回归,从中可挑选最优回归模型。本文将分析ＣＳＲ的原理,给出一种可行的快速的ＣＳＲ算法（ＲＣＳＲ）,以提高计算速率和精度,并将其成功地应用于苯乙酰胺类除草剂定量构效关系的建模。     

模式识别技术用于果酸混合物分析

研究了偏最小二乘法和人工神经网络法用于水果的紫外可见多组分光度分析。当混合物中诸组分存在相互作用，光谱加和性受到 扰动时，ＰＬＳ法和ＡＮＮ法用于混和物的分析仍能得到较满意的结果。     

拉曼光谱同时测定乙醇与葡萄糖的方法研究

以共焦拉曼光谱技术为基础,结合96孔板,对比利用一元线性回归法、多元线性回归法、主成分回归法和偏最小二乘法建立定量分析模型,探索同时定量检测乙醇和葡萄糖的快捷方法。对同一组乙醇和葡萄糖混合标准溶液进行定量检测,并用木薯淀粉发酵液进一步验证。结果表明,偏最小二乘法定量结果的平均标准误差(SE)为0.179,平均相对标准偏差(RSD)为0.029,结合二阶导数后分别降至0.106和0.021,说明偏最小二乘法具有良好的紧密度和稳定性;t检验表明,在置信度为95%的条件下,实测值与标准值间不存在显著性差异。研究表明基于拉曼光谱技术的偏最小二乘回归定量方法,能满足实验和生产对乙醇和葡萄糖检测精度的要求,可用于乙醇和葡萄糖相关成分的同时快速检测。     

偏最小二乘（PLS）分光光度法同时测定镉,汞,铅

本文研究了溴化十六甲铵基（ＣＴＭＡＢ）存在时，ｍｅｓｏ－四（４－磺酸苯基）卟啉（ＴＰＰＳ４）与Ｃｄ（ＩＩ），Ｈｇ（ＩＩ），Ｐｂ（ＩＩ）在室温下发生高灵敏度的显色反应条件以及应用偏最小二乘（ＰＬＳ）法同时测定三组分的方法。由微型计算机处理实验数据可心到三组分的浓度，本文还定义了未知样品与标准样之间的相关系数Ｑｒ，通过Ｑｒ值的大小预报未知样测试结果的准确性，利用此法可以提高测定速度，可靠性和选择性。     

6种化学计量学法同时分光光度测定5组分的比较研究及食品分析

优化了在表面活性剂存在下以肉桂基荧光酮同时测定铝、铜、锰、锌、钴的显色折衷条件；比较研究了偏最小二乘、岭回归、多元线性回归、多元逐步回归、目标因子分析和卡尔曼滤波法用于这一体系同时测定此５组分的优缺点，结果表明对于此类所含各组分吸收光谱重叠严重且吸光度加和性欠佳体系，上述６法中以偏最小二乘和岭回归法为最适宜；经用于九种人工合成液和四种食品分析，均获满意结果，分析两种茶叶结果也与ＩＣＰ－ＡＥＳ法一致     

傅里叶变换用于铁和锌的同时光度测定

研究了傅里叶变换技术用于铁锌二组分的同时分光光度测定，采用傅里叶变换对吸光度数据进行预处理，再结合目标转换因子分析或偏最小二乘分析，结果较普通的目标转换因子分析或偏最小二乘法有显著改善。以傅里叶变换－偏最小二乘法就用于实际铝合金样品中铁和锌的同时测定，结果令人满意。     

Investigation on the relationship between analytical precision and concentration with iteratively reweighted least-squares linear regression method

It is very important to investigate the relationship between analytical precision and concentration for quality control and assessment of analytical results. A set of analytical data of trace elements in soil and water deposits (Chinese certified reference materials) was studied for the relationship between the analytical precision of collaboration trials (i.e. reproducibility) and the concentration of the analytes. Iteratively reweighted least-squares (IRLS) linear regression, a robust method, was employed in this study. The linear relationship between the standard deviation and concentration was successfully established. On comparison with the conventional least-squares (LS) method , the results of IRLS linear regression are superior to those of LS.     

The effect of influential data, model and method on the precision of univariate calibration

Building a calibration model with detection and quantification capabilities is identical to the task of building a regression model. Although commonly used by analysts, an application of the calibration model requires at first careful attention to the three components of the regression triplet (data, model, method), examining (a) the data quality of the proposed model; (b) the model quality; (c) the LS method to be used or a fulfillment of all least-squares assumptions. This paper summarizes these components, describes the effects of deviations from assumptions and considers the correction of such deviations: identifying influential points is the first step in least-squares model building, the calibration task depends on the regression model used, and finally the least squares LS method is based on assumptions of normality of errors, homoscedasticity, independence of errors, overly influential data points and independent variables being subject to error. When some assumptions are violated, the ordinary LS is inconvenient and robust M-estimates with the iterative method of reweighted least-squares must be used. The effects of influential points, heteroscedasticity and non-normality on the calibration precision limits are also elucidated. This paper also considers the proper construction of the statistical uncertainty expressed as confidence limits predicting an unknown concentration (or amount) value, and its dependence on the regression triplet. The authors' objectives were to provide a thorough treatment that includes pertinent references, consistent nomeclature, and related mathematical formulae to show by theory and illustrative examples those approaches best suited to typical problems in analytical chemistry. Two new algorithms, calibration and linear regression written in s-plus and enabling regression triplet analysis, the estimation of calibration precision limits, critical levels, detection limits and quantification limits with the statistical uncertainty of unknown concentrations, form the goal of this paper.     

Advances in methodology for the validation of methods according to the International Organization for Standardization. Application to the determination of benzoic and sorbic acids in soft drinks by high-performance liquid chromatography

Robust chemometric techniques such as least median of squares regression, H15 Huber estimator and Lenth's method are fundamental tools in the validation of analytical methods since they contribute the strategies needed to estimate efficiently parameters such as robustness, linear range, selectivity, accuracy (trueness and precision) and the capability of detection. In addition, the capability of discrimination defined as a generalisation of the capability of detection for any nominal concentration is evaluated. The new strategy proposed is applied to the validation of a chromatographic method for use in systematic analysis.     

Inter-laboratory comparison of liquid chromatographic techniques and enzyme-linked immunosorbent assay for the determination of surfactants in wastewaters

Seven laboratories participated in an inter-laboratory comparison exercise within the framework of the PRISTINE, SANDRINE and INEXsPORT European Union Projects. Solid-phase extraction (SPE) methodologies were used for the extraction of target analytes from wastewaters. The analytical strategies were based on liquid chromatography (LC) coupled to mass spectrometric (MS) or to fluorescent (FL) detection in all cases with the exception of one laboratory using a test-tube enzyme-linked immunosorbent assay kit. Samples were spiked with the surfactants nonylphenolpolyglycol ether, coconut diethanolamide, linear alkylbenzene sulfonate, nonylphenolpolyglycol ether sulfate, alkylpolyglycol ether and secondary alkane sulfonate. After enrichment on previously conditioned SPE cartridges, the SPE cartridges were distributed among the participating laboratories without the information about the amount of spiked surfactants. In addition, SPE cartridges loaded with a real-world environmental sample containing a tannery wastewater were also analyzed. The results of the programme showed that SPE followed by LC-MS techniques are reliable for the surfactants determination at submicrogram to microgram per liter levels in wastewaters. Inter-laboratory precision values were calculated as the reproducibility relative standard deviation (RSD(R)) which was determined from the reproducibility standard deviation (sR) and the average concentration at a particular concentration level. When data from all laboratories were pooled, the RSD(R) values ranged from 5.1 to 28.3% for the determination of target analytes. The most accurate result corresponded to that given for linear alkylbenzene sulfonates. Taking into account that different methodologies were used (including non-chromatographic techniques) and the complexity of the samples analyzed, it can be considered that acceptable reproducibility values were obtained in this inter-laboratory study.     

电感耦合等离子体原子发射光谱(ICP-AES)法测定镀锡钢板中的镀锡量

建立了电感耦合等离子体原子发射光谱(ICP-AES)法测定镀锡钢板中的镀锡量的方法。为避免复杂基体、溶样时间对测试结果产生干扰,采用标准加入法进行定量分析。通过实验,确定了溶样用盐酸的浓度、ICP仪器参数以及待测元素的分析线。考察了标准曲线的相关性、精密度和准确度等分析指标。结果表明,标准曲线成线性关系(R=0.998 8),检测结果的相对标准偏差仅为1.3%,与现有的国家标准分析方法——碘酸钾滴定法和X射线荧光光谱法进行对比实验,测量结果基本一致。     

Inter-laboratory trials for analysis of perfluorooctanesulfonate and perfluorooctanoate in water samples: Performance and recommendations

The ISO 25101 (International Organization for Standardization, Geneva) describes a new international standard method for the determination of perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) in unfiltered samples of drinking and surface waters. The method is based on the extraction of target analytes by solid phase extraction, solvent elution, and determination by high performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS). For the determination of the performance of this method, more than 20 laboratories from 9 different countries participated in an inter-laboratory trial in 2006. In addition, inter-laboratory trials were conducted in 2008 and 2009 for the analysis of perfluoroalkylsubstances (PFASs), including PFOS and PFOA, in water samples by following the protocols of Japanese Industrial Standard (JIS). Overall, the repeatability coefficients of variation (i.e., within-laboratory precision) for PFOS and PFOA in all water samples were between 3 and 11%, showing a adequate precision of the ISO and JIS methods. The reproducibility coefficients of variation (i.e., between-laboratory precision) were found to vary within a range of 7–31% for surface water and 20–40% for wastewater. The recoveries of PFOS and PFOA, as a measure of accuracy, varied from 84 to 100% for surface water and from 84 to 100% for wastewater among the samples with acceptable criteria for internal standards recovery. The determined concentrations of PFASs in samples compared well with the “true” values. The results of the inter-laboratory trial confirmed that the analytical methods are robust and reliable and can be used as a standard method for the analysis of target compounds in water samples.     

Validation of a solid phase extraction-high performance liquid chromatographic method for the determination of eprosartan in human plasma

In this work, a solid phase extraction-reversed phase high performance liquid chromatographic (SPE-RP-HPLC) method with photometric detection for monitoring the antihypertensive drug eprosartan has been validated in order to assure good quantitation of eprosartan in plasma samples obtained from patients under cardiovascular treatment. This analytical method was developed by using experimental design and quantitation was accomplished with the internal standard method. No interferences were observed from endogenous compounds of plasma and other drugs which are commonly co-administered in elderly patients. The recoveries of eprosartan from plasma samples, measured at three levels of the linear concentration range (150-4000 ng/mL) were found to be between 93.4 and 102.8%. The intraday and interday precision and accuracy (measured by relative standard deviation, RSD, and relative error, RE, respectively) were always lower than 13% (RSD) and 4% (RE). Stability studies showed that eprosartan stock solutions are stable for at least 3 months when stored at 8 degrees C and plasma samples containing the drug were stable at least during the whole analytical method.     

构建支持向量机-偏最小二乘法为药物构效关系建模

为研究药物构效关系积累样本数据的过程中,需为小样本建模。此时较易造成过拟合,影响模型的预测性能和稳定性。为此可用偏最小二乘(PLS)法从样本数据中成对地提取最优成分,消除自变量间的复共线性,并有效的降维,然后应用最小二乘支持向量机对成对成分进行非线性回归,并以基于误差修正的策略调整,使之更有效地表达自、因变量间的非线性关系。由此构建为EB-LSSVM-PLS算法,所建模型的预报精度高,稳定性良好。将其应用于新型黄烷酮类衍生物的QSAR建模,效果令人满意,其泛化性能优于其它方法。     

Estimation studies of strontium in simulated nuclear waste solutions by WDXRF

Estimation of strontium has been studied by wavelength dispersive X-ray fluorescence spectrometery (WDXRF) as an analytical technique using Sr K as an analytical line. Lower limits of detection, precision, and intensities were plotted against counting time and concentrations to assess optimum time for measurement, expected scatter of the results, and calibration curves for intensity to concentration relationship. For its assessment the best equations determined by regression and least squares fitting along with a standard multiple addition technique were applied to a complex fuel admixture and simulated nuclear fuel solutions at a bum up of 650 GJ/Kg after a 0.5-year cooling time.     

A coupled reagent of o-phthalaldehyde and sulfanilic acid for protein detection based on the measurements of light scattering signals with a common spectrofluorometer

A rapid and sensitive method for the determination of proteins is proposed with a coupled reagent of o-phthalaldehyde and sulfanilic acid by measuring the light scattering (LS) signals with a common spectrofluorometer. Mechanism investigations showed that o-phthalaldehyde couples at first with sulfanilic acid with fast speed and forms a new synthesized Schiff base dye, which then interacts with protein rapidly on acidic condition, resulting in greatly enhanced LS signals with the maximum peak located at 344 nm. Based on the linear relationship between enhanced LS intensities and concentrations of proteins, a novel assay of HSA and BSA is established in the linear range of 0.1-25.0 microg ml(-1) with the limits of detection (3sigma) being 13 ng ml(-1) depending on the concentration of the reagent. Results for sample detections of our method were consistent with the documented spectrophotometric method with CBB G250 assay.