CPA矩阵分光光度法同时测定三种酚

在无水乙醇介质中，对乙酰胺基酚，对氨基酚、对硝基酚三者的紫外吸收光谱相互严重重叠，用一般的光度分析手段无法同时测定。本文首次采用CPA矩阵法，不经分离直接测定了上述三组分的含量，实验结果表明：当选取216、234、260、292、312nm5个波长点作为CPA矩阵程序的最佳波长点时，该法对样品中各组分的平均回收率在100.2%－103.5%之间，结果较满意，与现行分析方法相比，本方法具有简便、快速的优点。本法已用于扑热息痛合成物中三组分含量的测定。     

On Criticality for Competing Influences of Boundary and External Field in the Ising Model

We continue a study of Schonmann (1994), Schonmann and Shlosman (1996), and Greenwood and Sun (1997) regarding the competing influences of boundary conditions and external field for the Ising model. We find a critical point B ₀ in the competing influences for low temperature in dimension d 2A7E; 2.     

Development and characterisation of an immunoaffinity chromatographic column for the on-line determination of the pesticide triclopyr

An immunoaffinity column for the selective extraction and concentration of the herbicide triclopyr from water samples and quantification on line by HPLC has been developed. The immunoaffinity device was prepared by immobilising triclopyr antibodies to hydrazide derivatized azlactona beds. Efficient desorption of bound triclopyr was achieved with 70% ethanol/water solution. The column was evaluated regarding selectivity, recovery, capacity, saturation volume and reusability. Obtained results show that immunoaffinity chromatography (IAC) can be used for quantitative extraction, concentration and determination of triclopyr from water samples.     

On‐line Liquid‐liquid Extraction Coupled to a Reversed Micellar‐mediated Chemiluminescence Detection System: Application to the Determination of Amino/Nitroaromatic Compounds

A simple and fast flow method for the trace level determination of p‐toluidine, 2‐methyl‐5‐nitroaniline, and 2,4‐dinitroaniline in aqueous samples is reported. These amino/nitroaromatics are related to trinitrotoluene (TNT) and appear during the degradation process of the explosive. The chemical principles of ion‐pair formation and liquid‐liquid extraction are applied: In aqueous acidic medium, the protonated analyte [HA]⁺ makes an ion‐pair with the tetrachloroaurate(III) ion, followed by on‐line ion‐pair extraction into the dichloromethane carrier used. After membrane separation, the CH₂Cl₂ containing the ion‐pair, [HA]⁺[AuCl₄]⁻, is mixed with the reversed micellar luminescent reagent of luminol (in 0.3 M Na₂CO₃) prepared from cetyl‐trimethylammonium chloride in CH₂Cl₂‐cyclohexane and the [AuCl₄⁻‐luminol chemiluminescence (CL) output is recorded. The detection limits (S/N> 3) are: p‐toluidine, 1.0 × 10⁻⁴M; 2‐methyl‐5‐nitroaniline, 1.0 × 10⁻⁷ M; 2,4‐dinitroaniline, 1.0 × 10⁻⁷ M, while the calibration curves are linear between 1.0 × 10⁻⁴ — 1.0 × 10⁻² M for all the compounds. Although spectral studies indicated the formation and extraction of a very small amount of the ion‐pair species, the reversed micellar‐mediated CL detection system provides an alternative procedure for the determination of degradation products of the explosive TNT in environmental aqueous samples.     

锆(Ⅳ)-香草基荧光酮-Tween 20络合显色反应研究及其分析应用

在0.24～0.36mol/L盐酸介质中和Tween20存在下,香草基荧光酮与锆(Ⅳ)发生灵敏的显色反应,有色络合物的最大吸收波长为530nm,表观摩尔吸光系数为1.39×10~5L·mol~(-1)·cm~(-1)。锆(Ⅳ)含量在0～12μg/25mL范围内符合比尔定律。方法适用于铝合金中锆的直接测定,结果令人满意。     

Modified Newton method in circular interval arithmetic

The modified Newton method for multiple roots is organized in an interval method to include simultaneously the distinct roots of a given polynomialP in complex circular interval arithmetic. A condition on the starting disks which ensures convergence is given, and convergence is shown to be quadratic. As a consequence, a simple parallel algorithm to approach all the distinct roots ofP is derived from the modified Newton method.The research reported in this paper has been made possible through the support and the sponsorship of the Italian Government through the Ministero per l'Universitá e la Ricerca Scientifica under Contract MURST 60%, 1990 at the Universitá di L'Aquila.     

火焰原子吸收光谱法测定砂金中金,银

本文研究了用王水溶解砂金样品，在１％王水介质中，使银生成氯化银沉淀与金定量分离。滤液控制１％王水介质用以测定金。沉淀用５％热硫有脲溶解，控制为１％硫脲介质用以测定银。利用本方法测定了砂金样品中金和银得到了满意结果。金的回收率为９９．６％－１００．８％，银的回收率为９７．２－９９．２％。     

Determination and correlation of the solubility of tricin in water and ethanol mixtures

The solubility of tricin in water and ethanol mixtures was measured over the temperature range of (288.15 to 328.15) K. The concentrations of tricin in the aqueous mixtures were assayed by the ultraviolet spectrophotometric method. The experimental solubility data indicated that the solubility of tricin increases with an increase in temperature and an enrichment in ethanol content. The two models, including the modified Apelblat equation and λh equation were used to correlate the experimental solubility data. The calculated solubility of tricin shows good agreement with the experimental results. Additionally, the estimation of thermodynamic properties including the activity coefficients, dissolution enthalpy, and entropy were obtained from the experimental data. Within the studied temperature range the dissolution process of tricin is endothermic, and the driving force is the entropy.     

Nanostructured Hexacyanoferrate Intercalated Ni/Al Layered Double Hydroxide Modified Electrode as a Sensitive Electrochemical Sensor for Paracetamol Determination

An electrochemical sensor for paracetamol (PC) based on the hexacyanoferate(III) intercalated Ni−Al layered double hydroxide (Ni−Al−HCF) was presented. The as‐prepared LDH structurally and morphologically was characterized by scanning electron microscopy, X‐ray diffraction, and Fourier transform IR. Electrochemical studies revealed that Ni−Al−HCF film modified glassy carbon (GC) electrode exhibited remarkable electrocatalytic activity toward the oxidation of paracetamol. The electrochemical behavior of PC on the Ni−Al−HCF film was investigated in detail. Under optimum experimental conditions, the electrocatalytic response of the modified GC electrode was linear in the PC concentration range 3×10⁻⁶⁻–1.5×10⁻³ mol L⁻¹, with a detection limit of 8×10⁻⁷ mol L⁻¹ (S/N=3), using hydrodynamic amperometry. In addition, the modified electrode exhibited good reproducibility, long‐term stability and anti‐interference property. The fabricated sensor was successfully applied to determination of PC in various pharmaceutical preparations such as tablets, oral solution, and oral drops. Finally, the method was validated by the analysis of paracetamol spiked human serum samples, and good recoveries were obtained in the range of 99.2–103 %.     

Second-order and higher-order multivariate calibration methods applied to non-multilinear data using different algorithms

We discuss and evaluate the current state of second-order and higher-order multivariate calibration methods devoted to the determination of compounds in non-multilinear data systems. We examine possible causes of multilinearity deviations:

(1)

a non-linear relationship between signal and analyte concentration;

(2)

a signal for a given sample that is non-multilinear; and,

(3)

component profiles that are not constant across the different samples.

We discuss the advantages and the limitations of the algorithms available to cope with these different situations.The review covers relevant analytical problems found in samples of environmental and biological interest, highlighting some significant examples, and evaluating the advantages and the limitations of the different algorithms available.