Hongyan Shan

Residue analysis of tetracyclines in milk by HPLC coupled with hollow fiber membranes-based dynamic liquid-liquid micro-extraction

A novel hollow fiber membranes-based dynamic liquid-liquid micro-extraction (HF-DLLME) coupled with HPLC-UV detection has been developed for the residue analysis of tetracyclines in milk samples without deproteinization and degreasing. The influences of experimental parameters were investigated and optimized. The method showed a good performance. The limits of detection (LOD) are in the range of 0.95-3.6μg/L. The recoveries in spiked samples range from 92.38 to 107.3%. The relative standard deviations (RSDs) are lower than 8.66%. The advantages of this method are simple operation, high efficiency, absence of sample carryover and low cost.

A novel UV-visible chemosensor based on the 8-hydroxyquinoline derivative for copper ion detection

A novel UV-visible chemosensor, 4-methyl-2-((quinolinyl-8-amino)methyl)phenol (MQAMP), was designed and synthesized. The spectral properties of its free and Cu2+-coordinated forms were characterized. Under the optimized conditions, MQAMP showed selective and sensitive sensing for copper ions in an ethanol solution. The binding of Cu2+ to MQAMP caused a marked enhancement of the absorbance, and an about 100 nm red-shift of the maximum absorption wavelength. Other ions including Mo6+, Li+, Cs+, As3+, Ca2+, Na+, Cd2+, K+, Mg2+, Pt2+, Sr2+, Ba2+, Al3+, Cr6+, Be2+, Fe3+, Ni2+, F−, CH3COO−, SO42−, NO3−, Cl−, CO32−, and SO32− displayed no significant interference in this detection of Cu2+. The chemosensor exhibited a dynamic response range for Cu2+ from 1.0 × 10−6 to 1.0 × 10−5 mol L−1 with a detection limit of 1.1 × 10−7 mol L−1 (3σ).

A novel 2-(2-Formyl-4-methyl-phenoxy)-N-phenyl-acetamide-based fluorescence turn-on chemosensor for selenium determination with high selectivity and sensitivity

A novel turn-on fluorescent chemosensor, 2-(2-Formyl-4-methyl-phenoxy)-N-phenyl-acetamide (FMPPA) was designed and synthesized, and its photophysical properties were characterized. Upon coordination with Se (IV), the chemosensor showed incredible fluorescence enhancement (turn-on), other alkali, alkaline earth, transitional metal ions, and common anions including Li(+), Na(+), K(+), Rb(+), Cs(+), Be(2+), Mg(2+), Ca(2+), Sr(2+), Ba(2+), Ni(2+), Cu(2+), Cd(2+), Zn(2+), Mn(2+), As(3+), Pt(4+), V(5+), Fe(3+), Mo(6+), Al(3+), CO3(2-), Cl(-), SCN(-), AC(-), NO3(-), F(-), SO4(2-) had no significant interference on Se (IV) determination. The chemosensor exhibits a dynamic response range for Se (IV) from 3.32 × 10(-7) to 2.63 × 10(-6)M, with a detection limit of 9.38 × 10(-9)M (3σ).

Water-soluble porphyrin as temperature sensor based on fluorescent enhancement

A novel water-soluble porphyrin[5,10,15,20-tetra(3-ethoxy-4-hydroxy-5-sulfonate)phenyl porphyrin, H2TEHPPS]_was designed and synthesized, which could be used as a potential fluorescence sensor to detect temperature changes. The studies were performed in solution phase and the concentration of H2TEHPPS was 2.0×10−5 mol/L. The optical properties of H2TEHPPS were investigated based on the UV and fluorescence spectra. The results show that the fluorescence intensity of H2TEHPPS is directly proportional to temperature in the range of 293–353 K. So H2TEHPPS can be used as a molecular temperature sensor in biomedical and other fields.

Conjugated polymer with carboxylate groups-Hg2+ system as a turn-on fluorescence probe for label-free detection of cysteine-containing compounds

In this work, a turn on fluorescent sensor, based on Hg2+ coordination conjugated polymer, was developed to detect cysteine-containing compounds. The fluorescence of conjugated polymer (poly(2,5-bis (sodium 4-oxybutyrate) -1,4 - phenylethynylene-alt-1,4-phenyleneethynylene; PPE-OBS) would be quenched by Hg2+ because of the coordination-induced aggregation and electron transfers of PPE-OBS toward Hg2+. When there were some cysteine-containing compounds in PPE-OBS-Hg2+ system, the fluorescence of PPE-OBS would be recovered. It indicated that the PPE-OBS-Hg2+ system could be used to detect cysteine-containing compounds. Under the optimized conditions, the experiment results showed that there were particularly linear range, high sensitivity and selectivity over other amino acids. The limit of detection (LOD) of cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) were 0.725μmolL-1, 0.982μmolL-1 and 1.21μmolL-1 by using this sensor. In addition, Cys standard recovery in several green tea drink and honey samples was also demonstrated. The recovery of Cys was range from 96.3 to 105.0% and RSD was less than 3.25%. The satisfactory results demonstrated that the proposed method could be as a potential fluorescent method for determining cysteine-containing compounds in real samples.

A facile fluorescent chemosensor based on a water-soluble porphyrin for Mo(6+) in aqueous solution.

A novel water-soluble porphyrin (5,10,15,20-tetra(3-ethoxy-4-hydroxy-5-sulfonate) phenylporphyrin, H2TEHPPS) was synthesized. H2TEHPPS exhibited high sensitivity and selectivity towards Mo(6+). The enhanced fluorescence response of H2TEHPPS after titration with Mo(6+) in aqueous solution at pH3.5 was attributed to the formation of an inclusion complex between the porphyrin ring and Mo(6+), which R(2)=0.999 from 10 to 1000μgL(-1), providing a detection limit of 1.5μgL(-1). The fluorescence response of H2TEHPPS towards Mo(6+) showed excellent selectivity over other transition metal cations.

Quantitative Near-infrared Spectroscopic Analysis of Trimethoprim by Artificial Neural Networks Combined with Modified Genetic Algorithm

A novel method for rapid, accurate and nondestructive determination of trimethoprim in complex matrix was presented. Near-infrared spectroscopy coupled with multivariate calibration(partial least-squares and artificial neural networks) was applied in the experiment. The variable selection process based on a modified genetic algorithm with fixed number of selected variables was proceeded, which can reduce the training time and enhance the predictive ability when coupled with artificial neural network model.

A selective and sensitive fluorescence probe for Se(IV) based on fluorescence quenching of gatifloxacin

A novel high selective and sensitive fluorescence probe termed gatifloxacin was discovered based on fluorescence “on-off” phenomenon in the presence of Se(IV). In the Tris-HCl/acetonitrile(3:7, volume ratio, Tris-HCl 0.05 mol/L, pH=7.3) system, the fluorescence intensity of gatifloxacin was linearly decreased with the concentration increase of Se(IV) in a range of 1.0×10–5―5.0×10–5 mol/L with a correlation coefficient of 0.9979(R2=0.9958) and in a range of 5.0×10–5―1.0×10–4 mol/L with a correlation coefficient of 0.9973(R2=0.9946). The detection limit of Se(IV) was 1.70×10–6 mol/L.

An Improved Pneumatic Nebulization Gas–Solid Microextraction Device Used to Detect Triazine Herbicides in White Spirit

The pneumatic nebulization gas-solid microextraction device fascinating us is because it directly atomized organic samples to cross a solid-phase microextraction (SPME) cartridge without any pretreatment. In this work, both the spray chamber and SPME column of the extraction device were heated. We found that this would significantly improve the extraction efficiency of this method. Then, this method was used to detect seven triazine herbicides (atraton, desmetryn, atrazine, terbumeton, terbuthylazine, terbutryn, and dipropetryn) in drinking alcohol samples. The experimental results indicated that this extraction procedure could conveniently, efficiently and accurately concentrate any triazine herbicides from drinking alcohol samples. The limits of detection (LODs) were from 0.08 to 0.23 μg L(-1), the limits of quantification (LOQs) were from 0.27 to 0.78 μg L(-1). We used this method to detect triazine herbicides in five white spirit samples. Four concentrations were chosen (5, 25, 50 and 100 μg L(-1)) as the amounts of spikes to investigate the recovery and precision of the present PN-GSME method. The recoveries ranged from 95.91 to 106.67%. The relative standard deviations were not more than 6.51%. Also this method matches the requirement of the maximum residue limits of the European Union.

A Novel Copper(II) Sensor Based on a Unique Water-soluble Porphyrin.

A unique water-soluble porphyrin [5,10,15,20-tetra(3-ethoxy-4-hydroxy-5-sulfonate)phenyl porphyrin, H2TEHPPS] was designed and synthesized, which could be used as a potential sensor for the determination of Cu(2+). Studies were performed in the solution. The concentration of H2TEHPPS was 5 μmol L(-1). The optical properties of H2TEHPPS were investigated based on the absorption spectra. The results show that the absorbance of H2TEHPPS at 417 nm is directly proportional to the concentration of Cu(2+) in the range of 0 - 2.5 μmol L(-1). H2TEHPPS can thus be used as a novel class of Cu(2+) sensors.