共查询到19条相似文献,搜索用时 140 毫秒
1.
混合线性分析-分光光度法同时测定微量锌、镉、汞 总被引:11,自引:0,他引:11
提出了以2-(5-溴-2-吡啶偶氮)-5-二乙氨基酚为显色剂分光光度法同时测定锌、镉、汞的新方法。由于在可见区3种络合物的吸收光谱具有相似的特征和严重重叠,本文采用混合线性分析进行光谱分辨,各组分的纯光谱则用最小二乘法从校正集中求出。讨论了显色条件,波长选择,纯光谱的确定和吸光度加合性等因素对测定的影响。方法具有简单,快速,准确等优点。已成功地应用于混合试样中锌、镉、汞的同时测定,并与同条件下偏最小二乘法的计算结果进行了对比。 相似文献
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偏最小二乘法辅助分光光度法同时测定痕量锰、铁、铜和锌 总被引:4,自引:0,他引:4
痕量Mn(Ⅱ)、Fe(Ⅲ)、Cu(Ⅱ)和Zn(Ⅱ)与2-(5-溴-2-吡啶偶氮)-5-二乙氨基苯酚和聚乙二醇辛基本基醚在pH8.8发生高灵敏的显色反应,所形成的三元胶束络合物的吸收光谱严重重叠,用偏最小二乘法(PLS)辅助分光光度法成功地同时测定了模拟试样及铝合金和饲料添加剂中上述四种痕量组分。结果表明,PLS法是化学计量学法中一种可适用于基体较复杂的实际试样中痕量组分同时分光光度测定的优良的多元计算方法。 相似文献
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偏最小二乘法-紫外光度法同时测定防腐剂尼泊金乙酯钠、山梨酸钾和苯甲酸钠 总被引:3,自引:1,他引:2
介绍一种快速、简便同时测定食用防腐剂尼泊金乙酯钠、山梨酸钾和苯甲酸钠的紫外光度法。在pH5.72的B—R缓冲溶液中对尼泊金乙酯钠、山梨酸钾和苯甲酸钠3组分混合溶液进行吸光度测定,所得的重叠波谱数据用主成分回归法(PCR)和偏最小二乘法(PLS)逆行处理,结果表明,偏最小二乘法的测定误差较小。尼泊金乙酯钠、山梨酸钾和苯甲酸钠的线性范围均为1~10mg/L,回收率为84.5%~108.2%。用该法对样品进行测定,获得了较好的定量分析结果。 相似文献
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偏最小二乘分光光度法同时测定痕量铁、锰、铜、锌、钴和镍 总被引:19,自引:0,他引:19
痕量Fe^3 ,Mn^2 ,Cu^2 ,Zn^2 ,Co^2 ,Ni^2 与2-(5-溴-2-吡啶偶氮)-5-二乙氨基苯酚(5-Br-PADAP)和溴化十六烷基三甲基铵(CTMAB)在PH8.3时发生高灵敏显色反应,所形成的三元胶束络合的吸收光谱严重重叠,采用偏最小二乘法(PLS)辅助分光光度法测定了合成试样及饲料中上述6种痕量组分,结果表明,PLS法是化学计量学中一种可适用于基体较复杂的实际试样中痕量组分分光度同时测定的多元计算方法。 相似文献
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同时测定合成样中铜钴镍钒含量的分光光度法--主成分回归法和偏最小二乘法比较 总被引:6,自引:1,他引:5
研究了主成分回归和偏最小二乘方法在多组分分光光度法分析中的应用,以5-Br-PADAP(2〔5-溴-2-吡啶)-偶氮〕5-二乙氨基苯酚)为显色剂,OP(聚乙二醇辛基苯基醚)作为增溶增稳剂,在pH=3.6的条件下,用主成分回归及偏最小二乘分光光度法同时测定了合成样中的铜、钴、镍、钒4组分含量,测定相对误差在-6.00%~4.00%之间。实验证明,对于加和性不好的体系偏最小二乘分光光度法要优于主成分回 相似文献
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傅里叶变换近红外光谱法同时定量分析水溶液中乙醇、果糖和葡萄糖 总被引:6,自引:0,他引:6
利用乙醇、果糖和葡萄糖在波数为14000-7500cm^-1范围内的吸收值,在近红外谱区用偏最小二乘法(PLS)对体系进行建模,并通过内部和外部样品校验确认最佳数据预处理方法。结果表明,乙醇在0.05-0.25L/L,果糖在0.01-0.05g/mL及葡萄糖在0.005-0.009g/mL的范围内外部校验模型较好的分别是在PLS中所用的一阶偏导(平滑点数是5)、二阶偏导(平滑点数是5)和直线消除法的数据预处理方法所建立的模型,其外部校验预测结果的相对误差在2%左右。此方法具有可同时测定不同样品,简便快速及成本低等优点。 相似文献
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钨、钼与水杨基荧光酮(SAF)形成三元络合物,以SAF作为显色剂,溴化十六烷基三甲铵(CTMAB)作为稳定剂,室温下,在500-540nm波长范围内测定其吸光值,将测定结果分别用偏最小二乘法(PLS)处理和经小波变换后用偏最小二乘法处理。结果表明,经小波变换后处理结果误差明显减小。 相似文献
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主成分-人工神经网络在近红外光谱定量分析中的应用 总被引:13,自引:0,他引:13
近红外光谱的主成分由非线性迭代偏最小二乘法(NIPALS)求出。主成分作标准化处理后,作为B-P神经网络的输入结点进行非线性迭代。该法的优点是,充分利用了全光谱的数据,得到消除噪声后的最佳主成分,能建立非线性模型,B-P神经网络迭代时间显著缩短。用该法对大麦中的淀粉含量进行了定量分析研究。结果为:校准和预测的相关系数分别为0.981和0.953,校准和预测的相对标准偏差分别为1.70%和2.48%。 相似文献
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A novel method named a wavelet packet transform based Elman recurrent neural network (WPTERNN) was proposed for the simultaneous
UV–visible spectrometric determination of Cu(II), Cd(II) and Zn(II). This method combined wavelet packet denoising with an
Elman recurrent neural network. A wavelet packet transform was applied to perform data compression, to extract relevant information,
and to eliminate noise and collinearity. An Elman recurrent network was applied for nonlinear multivariate calibration. In
this case, using trials, the kind of wavelet function, the decomposition level, and the number of hidden nodes for the WPTERNN
method were selected as Daubechies 14, 3, and 8, respectively. A program (PWPTERNN) was designed that could perform the simultaneous
determination of Cu(II), Cd(II) and Zn(II). The relative standard errors of prediction (RSEP) obtained for all components
using WPTERNN, a Elman recurrent neural network (ERNN), partial least squares (PLS), principal component regression (PCR),
Fourier transform based PCR (FTPCR), and multivariate linear regression (MLR) were compared. Experimental results demonstrated
that the WPTERRN method was successful even where there was severe overlap of spectra. The results obtained from an additional
test case also demonstrated that the WPTERNN method performed very well.
Figure The part of WP coefficients obtained by wavelet packet transforms 相似文献
13.
构建支持向量机-偏最小二乘法为药物构效关系建模 总被引:6,自引:0,他引:6
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。 相似文献
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Morteza Bahram Khalil Farhadi Abbas Afkhami Donya Shokatynia Farzin Arjmand 《Central European Journal of Chemistry》2009,7(3):375-381
A partial least squares (PLS-1) calibration model based on kinetic—spectrophotometric measurement, for the simultaneous determination
of Cu(II), Ni(II) and Co(II) ions is described. The method was based on the difference in the rate of the reaction between
Co(II), Ni(II) and Cu(II) ions with 1-(2-pyridylazo)2-naphthol in a pH 5.8 buffer solution and in micellar media at 25°C.
The absorption kinetic profiles of the solutions were monitored by measuring the absorbance at 570 nm at 2 s intervals during
the time range of 0–10 min after initiation of the reaction. The experimental calibration matrix for the partial least squares
(PLS-1) model was designed with 30 samples. The cross-validation method was used for selecting the number of factors. The
results showed that simultaneous determination could be performed in the range 0.1-2 μg mL−1 for each cation. The proposed method was successfully applied to the simultaneous determination of Cu(II), Ni(II) and Co(II)
ions in water and in synthetic alloy samples.
相似文献
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In the present study, Quantitative Structure-Activity Relationship (QSAR) modeling has been carried out for lipid peroxidation
(LPO)-inhibition potential of a set of 27 flavonoids, using structural and topological parameters. For the development of
models, three methods were used: (1) stepwise regression, (2) factor analysis followed by multiple linear regressions (FA-MLR)
and (3) partial least squares (PLS) analysis. The best equation was obtained from stepwise regression analysis (Q2 = 0.626) considering the leave-oneout prediction statistics.
相似文献
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用凝胶法生长了标题配合物[NH_4(B15C5)_2][Cd(SCN)_3]的晶体,并对其进行了红外光谱,元素分析等各项物理性质的测试。经X射线单晶结构分析得到了配合物的全部晶体学数据:M_r=841.31,正交晶系,空间群P2_12_12_1,晶胞常数a=10.970(3),b=21.834(3),c=15.563(4),V=3727(3),Z=4,D_x=1.50g/cm ̄3,F(000)=1736,μ=7.09cm ̄(-1),R=0.070,R_w=0.063。结构分析结果表明,配阳离子[NH_4(B15C5)_2] ̄+和配阴离子[Cd(SCN)_3] ̄-间靠静电力结合成配合物。 相似文献
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Ashraf M. M. Abusenaina Viera Vojteková Karol Flórián Zuzana Poperníková Vladislava Mičková Miroslava Hámborská Silvia Ružičková 《Central European Journal of Chemistry》2014,12(6):678-686
Production of new catalysts requires effective analytical quality control. The study of trace element composition of heterogeneous catalysts, based on C+PdO, using atomic emission spectrometry (AES) was carried out. A new method for the direct solid-state analysis by means of AES with direct current arc discharge was developed. On the basis of the qualitative analysis of elements, Al, Fe, Ni, Si and Ti have been identified, and for these elements, the quantitative method of determination has been developed. Optimization of excitation parameters and validation of the analytical method are presented. Calibration samples of the following composition were prepared: graphite powder (as a matrix), 3% of PdO and increasing contents of determined element oxides (spectrally pure). Calibrations were calculated by means of the least squares method. Working range for element impurities was from 1% to 0.0003%, and the limits of quantification — LOQ, (10-σ criterion) varied in the range from 0.002% (Ti) to 0.0038% (Si). For the control of active component, palladium was calibrated (working range — 0.01%–10.00%; LOQ ?0.027%). The developed method can be used, also, for the elemental determinations of the other carbon based catalysts with the different active components (of platinum group elements). 相似文献
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Least-squares support vector machines and near infrared spectroscopy for quantification of common adulterants in powdered milk 总被引:5,自引:0,他引:5
This paper proposes the use of the least-squares support vector machine (LS-SVM) as an alternative multivariate calibration method for the simultaneous quantification of some common adulterants (starch, whey or sucrose) found in powdered milk samples, using near-infrared spectroscopy with direct measurements by diffuse reflectance. Due to the spectral differences of the three adulterants a nonlinear behavior is present when all groups of adulterants are in the same data set, making the use of linear methods such as partial least squares regression (PLSR) difficult. Excellent models were built using LS-SVM, with low prediction errors and superior performance in relation to PLSR. These results show it possible to built robust models to quantify some common adulterants in powdered milk using near-infrared spectroscopy and LS-SVM as a nonlinear multivariate calibration procedure. 相似文献