Yu Ruqin

Accuracy criteria and optimal wavelength selection for multicomponent spectrophotometric determinations

Abstract The most important criteria for evaluation of the precision and accuracy of multicomponent spectrophotometric determinations are compared. The basic statistical characteristics of these criteria and their logical relationship are discussed in detail. Two new algorithms based on the determinant criterion are proposed for selection of an optimal set of analytical wavelengths. The branch/bound algorithm can be used if the number of analytical wavelengths is predetermined, while the forward stepwise selection algorithm is preferable for overdetermined measurements.

Intercalation of Pharmorubicin Anticancer Drug to DNA Studied by Cyclic Voltammetry with Analytical Applications

ABSTRACT Variations of the cyclic voltammetric behavior of pharmorubicin in an aqueous medium upon addition of DNA were studied and utilized for the determination of DNA. It was observed that the redox waves of pharmorubicin after binding to the large and slowly diffusing DNA almost disappeared. The anodic peak currents of pharmorubicin, when the concentrations were fixed at 2.0 x 10−5 and 2.0 x 10−4 mol/L, decreased linearly correlated to the concentration of DNA added in the range of 0 - 30.7 and 0 - 260.3 μg/ml, with the detection limits of 1.2 and 20.8 μg/ml, respectively. The proposed method exhibited good recovery and reproducibility for the determination of DNA. Furthermore, the binding constant and binding site size of the pharmorubicin-DNA interaction were also calculated.

Determination of carboxylic acid vapour by a thickness-sheer-mode acoustic wave sensor coated with crown ethers

The frequency response sensitivities for 39 organic vapours by thickness-sheer-mode (TSM) acoustic wave sensors coated with monobenzo-15-crown-5 (B15C5), monobenzo-18-crown-6 (B18C6) and dibenzo-30-crown-10 (DB30C10) have been reported. It shows that crown ethers are the most efficient adsorptively active material for sensing carboxylic acid vapour, particularly B15C5 can be used for sensing formic acid vapour. The B15C5 based sensor possesses good reproducibility, high stability and short response time with wide linear detection range and a low detection limit down to 0.0201 mg l(-1) (about 5.70 ppm, V/V) of formic acid vapour while coating with 12 mug of B15C5. There is no significant interference from other organic vapours except for some nitrogen containing compounds such as diethylamine, pyridine and N,N-dimethylformamide, and carboxylic acid homologues such as acetic and propionic acids. The effect of humidity is easily controllable. Compared with acid-base titration method, the sensor can be used for the determination of HCOOH vapour with recovery rate of 98.4 approximately 103.8%, the analytical results are in good agreement with those obtained by the more time consuming acid-base titration method.

Polymer agglutination-based piezoelectric immunoassay for the determination of human serum albumin

Abstract Based on the detection of agglutination of antibody- or antigen-bearing polymer by an immunoreaction using a piezoelectric quartz crystal, a piezoelectric immunoassay technique was developed for the determination of human serum albumin (HSA). The effect of experimental conditions including the polymer concentration, the antibody dilution ratio and the reaction temperature on the frequency response were investigated. The frequency responses were linearly correlated to the concentrations of HSA in the range of 112 – 878 μg ml−1. Other antigens present in serum did not interfere significantly with the determination of HSA. Analytical results of five clinical specimens obtained using the developed technique were in satisfactory agreement with those given by the rate diffusion turbidimetry.

A sensitive nicotine sensor based on molecularly imprinted electropolymer of o-aminophenol

A sensitive nicotine sensor based on a molecularly imprinted electropolymer of o-aminophenol is proposed and its configuration and performance are studied in detail. On the condition of weak acidity, the sensitive layer was prepared by electropolymerization of o-aminophenol on a gold electrode in the presence of the template (nicotine). The sensor exhibits good selectivity and sensitivity to nicotine. The determination limit is 2.0×10−7 mol/L and a linear relationship between the current and concentration is found in the range of 4.0×10−7 ∼ 3.3 ×10−5 mol/L. The sensor has also been applied to the analysis of nicotine in tobacco samples with recovery rates ranging from 99.0% to 102%.

A new alternating weighted quadrilinear decomposition algorithm with application for analysis of non-quinquelinear five-way data arrays

In the work, a new method based on firstly expanding before processing was proposed to investigate the non-quinquelinear five-way data produced in the study. The five-way data array was firstly rearranged into an expanded four-way data array along the non-linear way, then it was decomposed by four-way calibration based on four way-PARAFAC, alternating weighted residue constraint quadrilinear decomposition (AWRCQLD) and newly presented alternating weighted quadrilinear decomposition (AWQLD). Before processing real data, a simulated fluorescence data and a simulated chromatographic data were used to verify the proposed method. It was found that the results of AWQLD were similar to or ever better than the ones of PARAFAC and AWRCQLD. These results indicated that the developed method possessed great potential to deal with non-multilinear multidimensional data.

Simple algorithm for selection of the optimal sequence of chromatographic columns

Abstract A computationally efficient scanning algorithm is proposed for selecting the optimal sequence of chromatographic columns. No approximations are involved.

Chapter 7 Classification of materials

Publisher Summary This chapter discusses classification of materials by using cluster analysis. Cluster analysis as an unsupervised pattern recognition method is an important tool in exploratory analysis of chemical data. Simulated annealing (SA), which derives its name from the statistical mechanics simulating the atomic equilibrium at a fixed temperature, belongs to a category of stochastic optimization algorithms. A modified clustering algorithm based on a combination of simulated annealing with the K-means algorithm (SAKMC) can also be used for classification. In this procedure, the initial class labels among k classes of all n samples are obtained by using the K-means algorithm instead of random assignment. In the study given in the chapter, the algorithm is firstly tested on two simulated data sets and then used for the classification of calculus bovis samples and Chinese tea samples. The results show that the algorithm that is guaranteed in obtaining a global optimum with shorter computation time compares favorably with the original SAC and K-means algorithm.