阻抑动力学光度法同时测定痕量铅和镉

基于氨水溶液介质中,痕量镉和铅阻抑过氧化氢氧化偶氮胂Ⅰ褪色的作用,建立了动力学光度法同时测定痕量铅和镉的新方法。方法测定铅、镉的线性范围分别为0.005~0.50μg/mL和0.002~0.80μg/mL。用于实际样品中铅、镉同时测定。     

二次旋转设计和反向人工神经网络在铅、镉、汞、镍同时测定中的应用

利用二次通用旋转组合设计法建立了吸光度与显色剂,增敏剂用量及pH 值之间的数学模型,进而得出使吸光度最大的显色剂用量,增敏剂用量及PH值,在优化的基础上,用B－P人工地Pb,Cd,Hg,Ni同时测定的数据进行解析,并与经典最小二乘法进行了对比,结果较准确。     

径向基神经网络微分脉冲溶出伏安法同时测定铅、镍和镉

径向基函数神经网络(RBFN)用于分析重叠的伏安信号;一个名为径向基神经网络的程序(PRBFN)被设计用于执行有关计算;RBFN法成功地应用于微分脉冲阳极溶出伏安法同时测定Pb(Ⅱ),Ni(Ⅱ)和Cd(Ⅱ);RBFN和偏最小二乘(PLs)法的所有组分相对预测标准偏差(RSEP)分别为4．8％和5．6％;试验结果表明RBFN法是解决局部最小和改善收敛速率的一种有价值的工具。     

催化动力学光度法同时测定痕量铅和镉

在十六烷基三甲基溴化铵（CTAB）存在下,痕量的Pb(Ⅱ）和Cd(Ⅱ）在硼酸－氯化钾－氢氧化钠缓冲体系中,能同时催化过硫酸铵氧化焦锫酚红（PR）而发生褪色指示反应,通过研究该反应的最佳反应条件以及将多元线性回归（MIR）用于数据处理,建立了同时测定铅和镉的新方法,方法已用于废水及铜混中铅和镉的同时测定。     

电位溶出法同时测定锌镉铅的研究

探讨了一种同时测定锌、镉、铅的溶出分析方法。在 0 .0 17mol·L- 1H2 SO4 HNO3混合酸介质中 ,用同位镀汞法在电位 - 1.5 0V条件下电解富集 60s ,锌、镉、铅分别在 - 1.0 7,- 0 .65及 - 0 .4 6V处有一良好的溶出峰 ,锌浓度在 0 .0 0 2 5～ 0 .0 2 5 μg·ml- 1,镉和铅在 0 .0 0 2 5～ 0 0 2 3μg·ml- 1范围内与峰高呈良好的线性关系 ,检出限锌为 0 .0 0 0 75 μg·ml- 1,镉和铅为 0 .0 0 0 70 μg·ml- 1。方法操作简便、快速、准确。用于环境水质标样、纯净水及自来水中锌、镉、铅的同时测定 ,均获得满意结果     

高压密闭消解-原子吸收光度法同时测定土壤中的铜、锌、铅、镉、镍、铬

采用高压密闭消解-原子吸收光度法同时测定土壤中铜、锌、铅、镉、镍、铬6种重金属元素。通过剖析不同消解体系,选择了最佳消解条件和测定条件。测定土壤中各元素的回收率均在86%～110%之间,相对标准偏差均小于8.0%(n=6)。     

流动注射—二极管阵列检测分光光度法同时测定铅和镉

建立流动注射－电荷耦合器件二极管阵理分光光度法装置，研究了以ｍｅｓｏ－四（４－三甲铵苯基）卟啉为显色剂同时测定铅和镉的方法，镉和铅测定的线性范围为０～２．０ｍｇ／Ｌ和０～２．５ｍｇ／Ｌ镉的检出限为０．０１４ｍｇ／Ｌ，铅为０．０１５ｍｇ／Ｌ。进样频率为６０次／ｈ，对合成样品和陶瓷食具容器浸泡液中铅和镉进行了同时测定，获得满意的结果，样品的平均标准加入回收率为１００．９％，相对标准偏差小于８．８％。     

ICP-AES法同时测定搪瓷餐具中铅镉锑镍的溶出量

采用ICP-AES法同时测定搪瓷餐具中铅、镉、锑、镍的溶出量,并对ICP-AES法测定乙酸（4％）浸泡液时分析线的选择,入射功率、护套气流量、载气压力的影响,以及基体和共存离子的干扰等进行研究。方法简便快速,回收率为100．8-104．0%,相对标准偏差为0．66％～1．75％。     

The Simultaneous Determination of Cu Pb Cd and Sb by Derivative Adsorption Chronopotentiometry

The behaviour of the complexes of copper,lead,cadmium and antimony with salicylfluorone(SAF)adsorbed on HMDE has been investigated by derivative chrono potentiometry in NH3/NH4C1.The dependence of the peak height on the dt/dE vs E curve on preconcentration time,the pH of solution and the constant reducing current are discussed.This method achieved the simultaneous determination of copper,lead,cadmium and antimony in human hair.     

Simultaneous determination of rifampicin and isoniazid by continuous-flow chemiluminescence with artificial neural network calibration

In this paper a continuous-flow chemiluminescence (CL) system with artificial neural network calibration is proposed for simultaneous determination of rifampicin and isoniazid. This method is based on the different kinetic spectra of the analytes in their CL reaction with alkaline N-bromosuccinimide as oxidant. The CL intensity was measured and recorded every second from 1 to 300 s. The data obtained were processed chemometrically by use of an artificial neural network. The experimental calibration set was 20 sample solutions. The relative standard errors of prediction for both analytes were approximately 5%. The proposed method was successfully applied to the simultaneous determination of rifampicin and isoniazid in a combined pharmaceutical formulation.     

Simultaneous kinetic determination of sulfite and sulfide using artificial neural networks

Artificial neural networks (ANNs) are proposed for the determination of sulfite and sulfide simultaneously. The method is based on the reaction between Brilliant Green (BG) as a colored reagent and sulfite and/or sulfide in buffered solution (pH 7.0) and monitoring the changes of absorbance at maximum wavelength of 628 nm. Experimental conditions such as pH, reagents concentrations, and temperature were optimized and training the network was performed using principal components (PCs) of the original data. The network architecture (number of input, hidden and output nodes), and some parameters such as learning rate (η) and momentum (α) were also optimized for getting satisfactory results with minimum errors. The measuring range was 0.05-3.6 μg ml⁻¹ for both analytes. The proposed method has been successfully applied to the quantification of the sulfite and sulfide in different water samples.     

The Simultaneous Determination of Cu Ph Cd and Sb by Derivative Adsorption Chronopotentiometry

Anodic stripping voltammetry (ASV) is an effective electroanalytical technique for themeasurement of trace metal ions. But there are serious interferences due to overlappingstripping peaks and forming of intermetallic complex in complicated system. The peak ofcopper (ASV) is close to that of mercury. So the result of determination of copper is notsatisfactory. Adsorption chronopotentiometry was reported by H.Eskilsson et al i. In thismethod, instead of electrolytic accumulation of metal io…     

Simultaneous determination of antimony and bismuth by beta-correction spectrophotometry and an artificial neural network algorithm

Simultaneous determinations of antimony and bismuth were done by β-correction spectrophotometry and a feed forward neural network algorithm with back propagation of error. The sensitivity was improved using β-correction spectrophotometry. The determination of trace amounts of mixtures of Sb and Bi in various matrices (river, tap and industrial wastewater) were investigated by neural network and β-correction spectrophotometry using the complexes formed between pyrogallol red, Sb and Bi. The results showed that measurement is possible in the ranges of 0.05-5.0 and 0.2-3.2 μg ml⁻¹ for Sb(III) and Bi(III), respectively. The results also show very good agreement between true and predicted concentration values and have the ability to use in routine analysis.     

Simultaneous determination of three organophosphorus pesticides residues in vegetables using continuous-flow chemiluminescence with artificial neural network calibration

In this article, a continuous-flow chemiluminescence (CL) system with artificial neural network calibration is proposed for simultaneous determination of three organophosphorus pesiticides residues. This method is based on the fact that organophosphorus pesticides can be decomposed into orthophosphate with potassium peroxodisulphate as oxidant under ultraviolet radiation and that the decomposing kinetic characteristics of the organophosphorus pesticides with different molecular structure are significantly different. The produced orthophosphate can react with molybdate and vanadate to form the vanadomolybdophosphoric heteropoly acid, which can oxidize luminol to produce intense CL emission. The CL intensity of the solution was measured and recorded every 2 s in the range of 0-250 s. The obtained data were processed chemometrically by use of a three-layered feed-forward artificial neural network trained by back-propagation learning algorithm, in which input node, hidden node and output nodes were 65, 21 and 3, respectively. The proposed multi-residue analysis method was successfully applied to the simultaneous determination of the three organophosphorus pesticides residue in some vegetables samples.     

Simultaneous determination of Co, Ni, Cu and Zn ions in foodstuffs and vegetables with a new Schiff base using artificial neural networks

New complexes of Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺ with a recently synthesized Schiff base derived from 3,6-bis((aminoethyl)thio)pyridazine were applied for their simultaneous determination with artificial neural networks. The analytical data show the ratio of metal to ligand in all metal complexes is 1:1. The absorption spectra were evaluated with respect to Schiff base concentration, pH and time of the color formation reactions. It was found that at pH 10.0 and 60 min after mixing, the complexation reactions are completed and the colored complexes exhibited absorption bands in the wavelength range 300-500 nm. Spectral data was reduced using principal component analysis and subjected to artificial neural networks. The data obtained from synthetic mixtures of four metal ions were processed by principal component-feed forward neural networks (PCFFNNs) and principal component-radial basis function networks (PCRBFNs). Performances of the proposed methods were tested with regard to root mean square errors of prediction (RMSEP%), using synthetic solutions. Under the working conditions, the proposed methods were successfully applied to simultaneous determination of Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺ in different vegetable, foodstuff and pharmaceutical product samples.     

原子吸收光谱法测定水生生物体内铜、锌、镍、铬、铅、镉

用硝酸-高氯酸体系消解螺蛳和水葫芦样品,采用火焰原子吸收光谱法测定铜、锌、镍、铬,用石墨炉原子吸收光谱法测定铅、镉。铜、锌、镍、铬、铅、镉的检出限分别为0.328、0.126、0.271、0.416、0.006 64、0.001 15 mg/kg,线性相关系数不小于0.999 0,测定结果的相对标准偏差为1.1%~3.7%,加标回收率为86.0%~94.2%。     

Simultaneous determination of speciation parameters of Cu,Pb, Cd and Zn in model solutions of Suwannee River fulvic acid by pseudopolarography

There is a growing awareness of the importance of quantitative determinations of speciation parameters of the trace metals Cu, Zn, Cd and Pb in aqueous samples containing chemically heterogeneous humic substances, especially when they are present together, interacting with one another and competing for specific binding sites of the humic substances. Such determinations require fundamental knowledge and understanding of these complex interactions, gained through basic laboratory-based studies of well-characterized humic substances in model solutions. Since the chemical heterogeneity of humic substances plays an important role in the thermodynamics (stability) and kinetics (lability) of trace metal competition for humic substances, a metal speciation technique such as pseudopolarography that can reveal the special, distinctive nature of metal complexation is required, and it was therefore used in this study. A comparison of the heterogeneity parameters (Gamma) for Zn(II), Cd(II), Pb(II) and Cu(II) complexes in model solutions of Suwannee River fulvic acid (SRFA) shows that GammaCd>GammaZn>GammaPb>GammaCu, suggesting that SRFA behaves as a relatively homogeneous complexant for Zn(II) and Cd(II), whereas it behaves as a relatively heterogeneous complexant for Pb(II) and an even more heterogeneous complexant for Cu(II) under the experimental conditions used. The order of values of log K* (from the differential equilibrium function, DEF) for the trace metals at pH 5.0 follow the sequence: log K*Cu>log K*Pb>log K*Zn>log K*Cd. These results are in good agreement with the literature values. The results of this work suggest the possibility of simultaneously determining several metals in a sample in a single experiment, and hence in a shorter time than required for multiple experiments.     

Simultaneous determination of Cd and Fe in grain products using direct solid sampling and high-resolution continuum source electrothermal atomic absorption spectrometry

Cadmium and iron are antagonistic elements in the sense that they produce different effects in the human body. Both elements have to be determined routinely in grain products, cadmium because of its toxicity, and iron because all grain products, according to Brazilian law, have to contain a minimum of 42 mg kg⁻¹ Fe to combat anemia. A routine screening method has been developed for the quasi simultaneous determination of cadmium and iron using high-resolution continuum source electrothermal atomic absorption spectrometry and direct solid sampling. The primary absorption line at 228.802 nm has been used for Cd, and an adjacent secondary line at 228.726 nm for the determination of Fe. Various chemical modifiers have been investigated, and a mixture of tungsten and iridium, applied as a permanent modifier, showed the best performance; it stabilized Cd up to a pyrolysis temperature of 700 °C and did not over-stabilize Fe. Two atomization temperatures were used sequentially, 1700 °C for Cd and 2600 °C for Fe, because of their significantly different volatilities. The characteristic masses obtained were 0.9 pg for Cd and 1.2 ng for Fe. The limits of detection (3σ, n = 10) were 0.6 μg kg⁻¹ for Cd and 0.5 mg kg⁻¹ for Fe. The relative standard deviation ranged from 3 to 7% for Cd and from 4 to 13% for Fe, which is satisfactory for the purpose. The accuracy of the method was confirmed by the analysis of three certified reference materials; the results were in agreement with the certified values at a 95% confidence interval. The Cd content in the investigated grain products was between 0.9 and 10.5 μg kg⁻¹, but most of them did not contain the required minimum amount of iron.