河南省城市居民消费结构比较研究

本文主要应用聚类分析方法 ,对河南省 17个地市级城市居民的消费结构进行了比较统计分析 ,从而得到了各城市居民消费结构的一些特点和规律 ,并进一步探讨了其消费结构、可支配收入与总消费支出之间的关系     

Biosensors based on highly sensitive acetylcholinesterases for enhanced carbamate insecticides detection

This paper presents the construction of amperometric biosensors for the highly sensitive detection of carbamate insecticides based on the inhibition of acetylcholinesterase (AChE). This enzyme was immobilised by entrapment in an optimised sol-gel matrix on TCNQ-modified screen-printed electrodes. The enzyme activity was estimated by measuring the thiocholine produced by the enzymatic hydrolysis of the acetylthiocholine using TCNQ as mediator. Wild and genetically engineered AChEs from Drosophila melanogaster (Dm) were chosen for their high sensitivity towards insecticides, which substantially improves the LOD compared with cholinesterases from other sources. The wild type and three mutant enzymes were tested against three carbamate insecticides: carbaryl, carbofuran and pirimicard. The best LOD were obtained with the Y370A mutant for carbaryl (1 × 10⁻⁸ M), the E69W mutant for pirimicarb (2 × 10⁻⁸ M) and the I161V mutant for carbofuran (8 × 10⁻¹⁰ M). The biosensors were applied to the analysis of two potable water samples.     

A Disposable Homemade Screen Printed Electrochemical Sensor for Vitamin B1 Determination in Multivitamin Ampoules: Potentiometric and Surface Morphology Studies

Thiamine chloride hydrochloride (TCH) is one of the B‐complex vitamins which resemble a very biologically important group of biomolecules. The first screen‐printed graphite ion‐selective sensor for the determination of TCH was prepared and characterized. The sensor is based on TCH‐tetraphenylborate as electrode material. A number of parameters such as the type of solvent mediator, weight percent of the ion‐exchanger, test solution temperature and possible interferences were extensively studied. Moreover, the surface morphology of the prepared sensor was studied using scanning electron microscopy. The sensor shows a Nernstian slope of 30.60±0.07 mV/decade, a low LOD of 5.08×10⁻⁶ mol/L and a wide applicability range of 5.96×10⁻⁶‐1.00×10⁻² mol/L. The sensing graphite ink remains usable for at least one month. Fast potentiometric response was obtained within 5 s and remains stable for at least 60 s. The sensor was applied to the analysis of TCH in pure solutions and multivitamin ampoules from the Egyptian market using the standard addition method and high recovery values of 97–102 % were obtained. Low %RSD values (0.27‐1.30) indicate high precision of the proposed sensor. Our sensor provides the advantages of disposability, simple preparation procedures, sensitivity and easy storage and transportation.     

Electrochemical Determination of the Effect of Caffeic Acid onto the Interaction between Idarubicin and DNA by Single‐use Disposable Electrodes

Now it is well known, antioxidant may affect the interaction of anticancer drugs and DNA. This study aims to investigate the interaction between Idarubicin and DNA and the effect of caffeic acid on this interaction. Disposable, inexpensive, easy handle electrodes were used in this study to investigate the interaction of idarubicin and DNA electrochemically. Idarubicin (IDR) is an anthracyline antitumor antibiotic, which used against one or more types of leukemia. Electrochemical behaviour of IDR was investigated by using cyclic voltammetry. The interaction between anticancer drug, IDR and calf thymus double‐stranded DNA (ctdsDNA) was investigated by using differential pulse voltammetry (DPV) technique in the absence and presence of caffeic acid.     

Disposable pipette tips extraction: Fundamentals,applications and state of the art

Disposable pipette tips extraction consists of a solid‐phase extraction in which the sorbent is poorly dispersed in a pipette tip, which allows a quick and dynamic contact between the aspirated analyte from the sample and the solid phase. It is a technique used particularly in food and forensic analysis, since it requires a small amount of sample and solvent. This article highlights the principles, advantages and disadvantages of the disposable pipette tips extraction method and reviews recent applications.     

Novel Enzymatic Potentiometric Approaches for Surfactant Analysis

The present study described a novel application of simple potentiometric enzymatic method for analysis of surfactants based on their inhibitory effect on acetylcholinesterase enzyme (AChE). The enzymatic activity was measured through monitoring hydrolysis of acetylcholine (ACh) with a disposable acetylcholine potentiometric sensor. Comprehensive investigations were carried out including the effect of incubation time, cholinesterase enzyme and the working calibration ranges. Based on inhibition of AChE, different cationic, anionic and nonionic surfactants were determined in the concentration range from 0 to 40 μg mL⁻¹ with detection limits reaching 0.07 μg mL⁻¹ depending on the nature of surfactants. The degree of AChE inhibition caused by different tested surfactants were as follows: cetylpyridinium chloride (CPC) > benzyldimethylhexadecyl ammonium chloride (BDHAC) > Hyamine (Hy)>cetyltrimethylammonium bromide (CTAB) > Triton X‐100 (TX‐100) > sodium dodecyl sulphate (SDS). The proposed method was applied for determination of surfactants in pharmaceutical formulation, detergents products and environmental samples with acceptable sensitivity and reproducibility.     

Measurement of Total Antioxidant Capacity by Electrogenerated Iodine at Disposable Screen Printed Electrodes

Total antioxidant capacity is an important parameter for the evaluation of the oxidative status in different kinds of biological samples such as plant extracts, or in food industry. We report a fast, easy, portable, cost‐effective electroanalytical method to measure total antioxidant capacity, based on the reaction of natural antioxidants with electrogenerated iodine using disposable platinum screen‐printed electrodes. This reaction can be measured by the increment of the electrochemical current signal of iodide oxidation to iodine during a voltammetric cycle. Iodine reacts with reducing compounds such as glutathione, ascorbate, gallic acid and NADH without interference of the corresponding oxidized counter‐parts. The addition of ascorbate oxidase also allows the concentration of ascorbate to be determined. The method was tested with real samples of plant extracts and the results correlated well with those obtained with a standard spectrophotometric method.     

Environmental monitoring using a conventional photographic digital camera for multianalyte disposable optical sensors

The primary interest of this study concerns the use of an inexpensive photographic digital camera as the detection system, using its own flash as the source of light to present a new analytical procedure to measure disposable multianalyte optical sensors for potassium, magnesium, hardness and conventional pH test strips. The camera arrangement was designed in a fixed position over an optical board with controllable ambient conditions. After acquiring the digital image, the analytical information contained in each test zone is analyzed using theRGB colour space. Reflectance measurements were developed to study the colourimetric and spectral characteristics of the test zones. We obtained the following application ranges and precision in terms of relative standard deviation (RSD %): for potassium from 3.2 × 10⁻⁷ to 0.1 M with a precision between 3.3 and 4.0%, for magnesium from 2.7 × 10⁻⁶ to 1.5 M showing a precision between 4.7 and 7.8% and finally for hardness from 4.3 × 10⁻² to 200,000 mg L⁻¹ CaCO₃ and between 5.1 and 7.0%. Moreover, the analytical characteristics of several optical procedures were compared with the results presented here. The proposed method was statistically validated against a reference procedure using samples of water from different sources and beverages, indicating that there are no significant statistical differences at a 95% confidence level.