Shu Long

A simple gold plate electrode modified with Gd-doped TiO2 nanoparticles used for determination of trace nitrite in cured food

A simple gold plate electrode (GPE) based on a gadolinium-doped titanium dioxide (Gd/TiO2) ultrathin film was successfully constructed by using a surface sol-gel technique, and used for the detection of trace amounts of nitrite in cured foods. The Gd/TiO2 nanoparticles were synthesised and characterised via scanning electron microscopy (SEM) and X-ray diffraction (XRD), indicating that the Gd-doped TiO2 formed an anatase phase through roasting at 450°C, generating actively interstitial oxygen at the interface of the surface of TiO2 lattice surrounded by Gd3+. The electro-catalytic effect for oxidation of nitrite on the modified electrode was investigated by cyclic voltammetry in 0.10 mol l−1 sulfuric acid media solution, showing that the modified electrode exhibited excellent response performance to nitrite with good reproducibility, selectivity and stability. The catalytic peak current was found to be linear with nitrite concentrations in the range of 8.0 × 10−7 to 4.0 × 10−4  mol l−1, with a detection limit of 5.0 × 10−7 mol l−1 (S/N = 3). The modified electrode could be used for the determination of nitrite in the cured sausage samples with a satisfactory recovery in the range of 95.5–104%, showing its promising application for food safety monitoring.

Multi-wall carbon nanotubes film used for determination of salbutamol sulfate

A multi-walled carbon nanotubes (MWNTs) film modified glassy carbon electrode (GCE) has been fabricated and showed potent electrocatalytic activity toward the electrochemical oxidation of salbutamol sulfate in phosphate buffer solution (pH=7.4). The linear dependence between the oxidation peak current of salbutamol sulfate and its concentration was observed in the range from 5.0 – 25 µmol/L with a detection limit of 1.0 µmol/L. The electrode possessed a nice recovery of 97.2 – 104.4% with good reproducibility and stability for detection of salbutamol sulfate aerosol samples, indicating that it was a feasible method for determination of salbutamol sulfate in actually pharmaceutical samples.

Fabrication of Mercury Ion Selective Electrode Based on a Porphyrin Derivative with Plasticized PVC Membrane

An electrochemical sensing device with a plasticized polyvinyl chloride (PVC) membrane electrode based on a porphyrin derivative of p-amino tetraphenyl porphyrin (p-NH2TPP) for mercury ion (Hg2+) has been fabricated. The p-NH2TPP based PVC membrane electrode exhibited a nice linear potential performance for responding to Hg2+ in the range of 1.0×10-8 ~ 1.0×10-3 mol/L with a slope of 27.54 mV/-pC (25°C) in citrate buffer solution (pH=2.5). The detection limit was evaluated to be 7.5×10-9 mol/L. No obvious interferences were observed from Na+, K+, Ba2+, Mg2+, Ca2+, and Cr3+. The electrode possessed good stability and reproducibility. Comparing with atomic absorption spectroscopy (AAS), the electrode can be well applied to the determination of trace amount of Hg2+ in environmental waste water samples with a recovery rate of 94.83 ~ 104.78%. The sensing mechanism of the porphyrin derivative carrier for recognition of Hg2+has also been expounded by the formation of nice complexation effect between the lone pair electrons provided by four nitrogen atoms of the porphyrin molecule and unoccupied orbitals provided by the mercury ion.

Detection of Carbon Dioxide in Transformer Oil with Coated Piezoelectric Quartz Crystal Sensor

In this paper, a piezoelectric quartz crystal (PQC) sensor has been developed with a coating material of N, N, N’, N’-tetrakis (2-hydroxyethyl) ethylenediamine (THEED). The active compound was selected from fifty-one adsorptive coating materials and was the most efficient one for sensing of carbon dioxide gas. The coated PQC sensor possessed an excellent linear response range of 0.3738 ~ 31.85% with a sensitivity of 53.81 Hz/% to CO2 gas after coating with 91.62 μg of THEED. The detection limit for CO2 gas could reach 100.0 ppm. The sensor also possessed good reproducibility and stability. There were no significant interferences from other gases dissolved in transformer oil such as carbon monoxide, hydrogen, methane, ethane, ethylene, and ethyne. The THEED coated PQC sensor has been successfully applied to the determination of CO2 samples dissolved in transformer oil, showing its promising application for generation set’s safety evaluation in power industry.

Investigation on Electronic Signals for Detection of Target DNA Molecule Based on Extended Gate FET Sensing Chip

An electronic detection method for DNA molecules based on an extended gate field effect transistor (EGFET) sensing chip has been presented in this paper, which consists of one gold plate electrode for molecule recognition and FET part for signal transduction. The DNA probe was prepared by first immobilization of a thiolated single-stranded oligonucleotide (T1) and then an alkanethiol such as 6-hydroxy-1-hexanethiol (6-HHT) on the gold plate. A fast cyclic voltammetry (FCV) was applied to quantification of DNA molecules by using a cathodic peak around -1.3 V at a electrode reaction, corresponding to reductive desorption in strong alkali solution. By using a 70.7 mV DC voltage onto a Ag/AgCl reference electrode, the electronic signals of EGFET were applied to detection of DNA molecules and its hybridization, and the corresponding hybridization efficient was estimated to be about 37.5%. About 1 ~ 4 DNA molecules per 100 nm2 on the Au substrate of EGFET could be counted, showing a promising sensing technique for bio-molecule.

Synthesis of 2, 6-Deoxyfructosazine and its Decomposition of Incense Flavor in Tobacco Smoke

2, 6-Deoxyfructosazine (1) was synthesized from glucose and ammonium formate and isolated from the reaction mixture by membrane technology. The compound was characterized by HRMS, 1HNMR,and 13CNMR. Thermal analysis of the product showed that it began to decompose at 220 °C, and its weight loss was about 50 % at 320 °C. GC/MS analysis of the tobacco smoke showed that it decomposed to produce 2-methylpyrazine, 2, 6-dimethylpyrazine and 2-ethyl-6-methylpyrazine in the smoke upon smoking.

Determination of Mercury Ions by Using Nano Gold Plate Electrode Based on Amino Thiol Self-Assembled Film

The electrochemical behaviors and sensing application of 100nm-gold plate electrode based on 6-amino-1-hexanethiol (6-AHT) self-assembled monolayer (SAM) have been investigated in this paper. The 6-AHT assembled nano gold plate electrode exhibited a nice linear potential performance of responding to Hg2+ in the range of 1.0×10-8—1.0×10-6 mol/L with a slope of 42.57 mV/-pC (25°C) in Tris-HCl buffer solution (pH=5.0). No obvious interferences were observed from Na+, K+, Ba2+, Mg2+, Ca2+, and Cr3+. The detection limit can be evaluated to 8.0×10-9 mol/L. In addition, the electrode possessed good stability and reproducibility with a recovery rate of 96.50-103.67%, indicating that it can be used for the determination of Hg2+ content in environmental waste water samples. The sensing mechanism of 6-AHT monolayer has also been discussed by the formation of coordination structure between amino groups of the thiol molecules and the mercury ions.

Fabrication of Piezoelectric Thickness-Shear-Mode Acoustic Wave Sensing Device and its Application

The piezoelectric thickness-shear-mode (TSM) acoustic wave sensing device was fabricated by coating with a calixarene derivative on the surface of gold electrode of quartz crystal, then connecting with a transistor-transistor-logic (TTL) oscillator, a frequency counter and a computer. Among four coating materials, the compound of calixarene I was the most efficient active material for adsorption of carbinol molecule based on a host-guest recognition mechanism. In comparison with gas chromatography (GC) method, the calixarene based TSM device can be used for on-line determination of the poisonous carbinol vapor in the range of 0 ~ 3000 ppm around our living environment with good selectivity, reproducibility and high stability. The detection limit can be evaluated to be 1.41 ppm.

Fabrication of Gold Cap-Shaped Nano-Particle Films and Sensing Device for Bioanalytical Application

The nano biosensors based on gold cap-shaped nano-particles like polystyrene and silica nanospheres have been successfully prepared on the substrates of disposable plate (96 wells) and miniplate (72 wells). The sensing film of carboxymethyl dextran layer was modified on the gold surface of the cap-shaped nano-particles. The corresponding micro-device with four channel of optical sensing system has been well constructed and applied to detection of anti-avidin D protein and biotinylated DNA molecules. The DNA hybridization reaction has also been real-time and parallel monitored in four channels, showing that the device possessed a nice reproducibility, which opens a promising bioanalytical application in practice.