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An improved ‘seed mediated growth’ method for preparing gold coated iron oxide nanoparticles is demonstrated herein. This method involves two steps. First, the seed gold nanoparticles were affixed to the surface of the iron oxide nanoparticles through amino groups. Second, by reducing HAuCl4 with glucose in the aqueous solution, the seed gold nanoparticles became larger, and a gold shell was formed on the surface of the magnetic nanospheres ultimately. These Au–Fe3O4 nanoparticles were characterised by X-ray powder diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy and vibration sample magnetometer. The characterisation results showed that this method can prepare gold shell coated iron oxide nanoparticles efficiently, and the prepared superparamagnetic hybrid Au–Fe3O4 nanoparticles possessed a saturation magnetisation of ∼27·9 emu g−1.

Fe3O4/CdSe/SiO2 bifunctional nanocomposites were successfully synthesised based on a feasible electrostatic self-assembly method at room temperature. Both the pH value of the system and the adsorption of cetyltrimethy ammonium bromide onto the Fe3O4 nanoparticles played essential roles in directing the structure of the bifunctional nanocomposites. Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, fluorescence spectroscopy and magnetometry were applied to fully characterise the prepared nanocomposites. The dispersion of the nanocomposites was stable, and the nanocomposites were found to exhibit fluorescent and magnetic properties favourable for a myriad of applications in guiding as well as fluorescent imaging and magnetic separation.

In this study, luminescent CdSe quantum dots (QDs) were modified with L-cysteine and used as a sensitive sensor for the detection of lead ion. The fluorescence of the water soluble QDs can be quenched only by Pb2+ in Kolthoff buffer solution. The optimum experimental conditions were as follows: pH=8·0, 8·0 × 10−4M L-cysteine, reaction time=3 min and reaction temperature=293 K. The fluorescence intensity of CdSe QDs was linearly proportional to lead ion concentration from 0 to 1·00 × 10−6M with a limit of detection of 8·39 × 10−8M. The fluorescence quenching mechanism was considered to be both dynamic and static quenching acting together as quenching model. The proposed method has been successfully applied to detect the content of Pb2+ in green tea, and the recoveries were found to be 102·9–108·3% with standard addition method.

In this study, a method for the separation and determination of basic analytes in aqueous capillary electrophoresis (CE) was developed based on high electric field strengths and ionic liquids (ILs). The resulting electric field strengths ranged from 500 to 1000 V/cm. Trishydroxymethylaminomethane (Tris) and sodium cholate (SC) were used as main electrolytes. The ionic liquids 1‐ethyl‐3‐methylimidazoium tetrafluoroborate (1E‐3MI‐TFB) and 1‐butyl‐3‐methylimidazoium tetrafluoroborate (1B‐3MI‐TFB) were used as modifiers to improve the separation efficiency and selectivity. It was shown that increasing the applied electric field strengths not only caused short analysis time, but also did not induce excessive Joule heating in the capillary when ionic liquids were used as modifiers. The susceptibility to high electric field of separation efficiency in capillary electrophoresis, with the effect of ionic liquids, was subsequently discussed, and the developed method was used to analyze three model analytes...

This paper presents a sequential injection spectrophotometric method for the determination of cationic surfactants (CS) on the basis of forming a coloured ion-associate complex of anionic dye, Bromophenol Blue (BB) with cationic surfactants, including zephiramine (Zeph), cyltrimethylammonium bromide (CTMAB) and cetylpyridinium bromide (CPB), and causing a red shift of λmax from 585 nm for Bromophenol Blue to 634 nm for CS+·BB− associate. The increased absorbance value is proportional to the concentration of cationic surfactant. Various chemical and physical parameters for the sequential injection spectrophotometric method were optimized. The linear ranges were 6.34–50.8 µg/mL for Zeph, 7.29–32.8 µg/mL for CTMAB and 7.50–40.0 µg/mL for CPB. The detection limits were 0.22 µg/mL, 0.29 µg/mL and 0.25 µg/mL for Zeph, CTMAB and CPB, respectively. The proposed system can be used to analyse 28 samples per hour with a relative standard deviation (RSD) lower than 4.1%. The method was applied to the determination of...

A kinetic method for measuring formaldehyde by sequential injection analysis (SIA) with spectrophotometric detection was developed for the first time. The method was based on the inhibitory effect of formaldehyde on the ethyl green (EG)–sulfite reaction. The linear range for formaldehyde was 1.0–20.0 µg mL−1; the detection limit was 0.020 µg mL−1. The measurement rate was 130 sec, thus allowing to analyze 27 samples per hour, the total reagent consumption in a cyclical procedure is only 240 µL. The method was applied to the determination of formaldehyde in fabric and air, and compared with acetyl acetone spectrophotometric method.

The synthesis of a new reagent, saturated fatty hydrocarbon substituting group compound N-n-hexyl-N ′-(sodium p-aminobenzenesulfonate) thiourea (HXPT), is described. The interactions between HXPT and bovine serum albumin or human serum albumin were studied by fluorescence spectroscopy. The binding constants of HXPT with BSA or HSA were determined at different temperatures under the optimum conditions. The binding sites were obtained and the acting force were suggested to be mainly hydrophobic. The effect of common ions on the binding constants was also investigated. A practical method was proposed for the determination of HXPT in bovine serum or human serum samples.

A simple and rapid capillary zone electrophoresis (CZE) method was proposed for the separation and quantitative analysis of atropine sulfate (AS), anisodamine hydrobromide (AH) and scopolamine hydrobromide (SH). The parameters affecting the migration behavior of these drugs were studied in detail, including the background electrolyte acidity and its concentration. In the optimized conditions, the method was used to determine the AS, AH and SH in various samples (Tablets, Injections and China herbal medicines of Hyoscyamus niger). The relative standard deviations of the migration time and the peak areas were 0.45–1.32% and 2.1–4.58%, respectively. The recovery of the three drugs ranges from 94.3 to 102.4%.

Based on the enhancement effects of Rayleigh light scattering (RLS) on Arsenazo-DBC, a novel quantitative method for the determination of proteins in aqueous solutions has been proposed. The reaction of Dibromochloroarsenazo (Arsenazo-DBC) and five proteins (BSA, HSA, egg albumin, human γ-IgG, Lysozyme) has been studied. Under optimal conditions the dynamic ranges for proteins were 2.5–60.0 μg·ml−1, and the detection limits for HSA and BSA were at 98.50 ng·ml−1 and 88.10 ng·ml−1, respectively. Comparing with other methods, the method is simple, practical and relatively free from interference from coexisting substances. The method was employed for the determination of total protein in human serum with satisfactory results.

A determination method of proteins with the limit of determination at nanogram levels is proposed by using a common spectrofluorometer to detect intensity of resonance light scattering (RLS). Under acidic conditions, the reaction between m-acetylchlorophosphonazo (CPA-mA) and proteins enhances the weak light scattering of CPA-mA drastically. The enhanced light scattering intensity is proportional to the concentration of proteins. The linear range of human serum albumin is 0.25–40.0 μg ml−1. The determination of human serum and urine by this method give the results comparable with those by the Coomassie Brilliant Blue G-250 colorimetry (CBB) with relative standard deviations of 1.7–2.54% (n = 6). There is almost no interference from amino acids and most of the ions tested.

Superparamagnetic Fe3O4 nanocrystals were prepared via chemical precipitation in reverse microemulsion at room temperature. The water-in-oil reverse microemulsion system was composed of Triton X-100 as a surfactant, n-butanol as a co-surfactant, cyclohexane as a continuous oil phase, and aqueous phase. Powder X-ray diffraction and transmission electron microscopy results demonstrated that the nanoparticles were pure Fe3O4 with a polyhedral spinel structure and with an average size of 15 nm. Moreover, the sizes of Fe3O4 nanoparticles did not change as water/surfactant mole ratios (W 0) increased from 5 to 60. From the magnetometer measurements data, the products exhibited superparamagnetic property with saturation magnetisations of 64·6 emu g−1 at room temperature. Such method was easy and mild, and could synthesise other metal oxide in such experiment situation.

Artificial Neural Networks (ANNs) with Extended Delta-Bar-Delta (EDBD) back propagation learning algorithm have been developed to predict the standard enthalpy and entropy of 87 acyclic alkanes. Molecular weight, boiling point and density of the compounds were used as input parameters. The network's architecture and parameters were optimized to give maximum performances. The best network was a 3-6-2 ANN, and the optimum learning epoch was about 1320. The results show that the maximum relative errors of enthalpy and entropy are less than 3%. They reveal that the performances of ANNs for predicting the enthalpy and entropy of alkanes are satisfying.

A simple, rapid, accurate, selective and reproducible capillary electrophoretic method was developed for the assay of oleanolic acid in traditional Chinese herb Ligustrum lucidum and its medicinal preparation. The buffer solution used in this method was 10% acetonitrile and 0.010 M borax solution adjusted to pH 7.50 with 0.10M hydrochloric acid. The Effects of pH value and modifier on the migration behavior of oleanolic acid was investigated and a simulated equation as well as the apparent dissociation constant were obtained. The linear calibration range was 0.040-1.50 mg/ml(r=0.9979). The relative standard deviation of the migration time of oleanolic acid was 0.46% under the optimized conditions. The content of it in Ligustrum lucidum and a kind of Ligustrum lucidum-containing Chinese medicinal preparation was succesfully determined within 4 min.

A new rapid, high sensitive and selective on-line microwave flow injection method has been developed for the determination of micro-amounts of ruthenium, based on its catalytic effect on the oxidation of dibromocarboxyarsenazo (DBM-AsA) by potassium periodide in acidic medium. The assay is performed in a microwave-induced flow injection analyzer by measuring the absorption of DBM-AsA at 538 nm spectrophotometrically.

A methodology based on the coupling of experimental design and artificial neural networks (ANNs) was proposed in the optimization of selectivity in capillary electrophoresis. The effect of the buffer composition, concentration, SDS concentration, ethanol percentage and the applied voltage on the separation of six choice solutes was examined by using orthogonal design. Feedforward-type neural networks with faster back propagation (BP) algorithm were applied to model the separation process, and then optimization of the experimental conditions was carried out in the modeled neural network with 5-7-1 structure, which had been confirmed to be able to provide the maximum performance. It was demonstrated that by combining ANN modeling with experimental design, the number of experiments necessary to search and find optimal separation conditions can be reduced significantly. Because of its general validity, the new proposed approach can also be applied in other separation conditions.

CdTe nanocrystals have been successfully synthesised by a simple and 'green' route using starch as a capping agent at room temperature. The prepared CdTe nanoparticles were characterised by XRD, TEM, UV-vis absorption and photoluminescence (PL) spectra. The XRD pattern and TEM images confirmed the formation of cubic structural CdTe nanocrystals (4–9 nm). The capped CdTe nanocrystals showed absorption peaks located within the visible range of 450–550 nm. The PL spectra indicated that their excitation and emission wavelength were located at 350 and 575 nm, respectively.

An on-line flow-injection-microwave oven system employed to accelerate chromogenic reactions is described. Effects of microwave on chromogenic reactions between Pt(II,IV) and 5-Br-PADAT in HOAc-NaOAc media are studied respectively, and a direct spectrophotometric flow-injection determination method for Pt(II) is established. The maximum absorption wavelength is 600nm for Pt(II), and 560nm for Pt(IV). This method is applied to the determination of platinum in fresh platinum catalyst with aluminum as support.