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Tang H.,Kunming University of Science and Technology | Geng W.,Kunming Productivity Promotion Center | Wang Q.,Kunming University of Science and Technology | Yang C.,Kunming University of Science and Technology | And 2 more authors.
Asian Journal of Chemistry | Year: 2012

A precise and reliable fluorimetric method for the determination of four sulfonamide antibiotics (sulfadiazine, sulfaguanidine, sulfamethoxazole, sulfamethazine) in milk samples has been developed. Sulfonamide in presence of o-phthalaldehyde produces an isoindole derivative, which can produce strong fluorescence. N-butanol was used for the extraction of the derivative to bring down the detection limit largely. Optimum conditions for the determination of sulfonamides were also investigated. Fluorimetric detection was carried out at λ ex of 295 nm and λ em of 425 nm. Linear ranges for sulfonamides determination were 5-500 mg/L. The developed method is practical and can be successfully applied to determine the content of sulfonamides residues in milk samples with satisfactory results.


Qin H.,Kunming University of Science and Technology | Yu G.,Kunming Productivity Promotion Center | Chen M.,Kunming University of Science and Technology | Zou Y.,Kunming University of Science and Technology | Yang Y.,Kunming University of Science and Technology
European Food Research and Technology | Year: 2012

A novel approach, ultrasonic-thermostatic-assisted cloud point extraction (US-CPE) combined with high-performance liquid chromatography and ultraviolet detection, is developed for the analysis of adrenalines (beclometasone dipropionate, hydrocortisone butyrate and nandrolone phenylpropionate) in milk samples. It is based on the induction of micellar organized medium by using a non-ionic surfactant TMN-6 (polyether-type organic silicon surfactant; structure: (CH 3)3C(CH 2)8(OC 2H 4)XOH; average of X = 6) to extract the target adrenalines. In this experiment, phase diagrams were used to study the cavitation and mass transfer behaviors of the two phases on micelles of TMN-6. The main advantages of this system were that it had no ultraviolet absorption and had higher extraction efficiency. In addition, the phase diagram of US-CPE was determined contrast with ultrasonic-thermostatic-cloud point system. The effects of other operating parameters, e. g., concentration of salt and centrifugation time on extraction of US-CPE system, have also been studied in detail. © 2012 Springer-Verlag.


Tang H.-N.,Kunming University of Science and Technology | Geng W.-D.,Kunming Productivity Promotion Center | Liu M.-S.,Kunming University of Science and Technology | Yang Y.-L.,Kunming University of Science and Technology
Chemical Research in Chinese Universities | Year: 2011

A simple sensitive spectrofluorimetric method was developed for the determination of amoxicillin. Amoxicillin in the presence of formaldehyde produces a fluorescent pyrazine derivative, whose fluorescence intensity can be enhanced by forming an inclusion complex with β-cyclodextrin. Optimum conditions for the determination of amoxicillin were also investigated. Fluorimetric detection was carried out at λex=365 nm and λem=445 nm. The linear range of this method for the determination of amoxicillin is 0.1-10 mg/L and the limit of detection is 0.03 mg/L (IF=102.16ρ-9.6, r=0.9994). The developed method is practical and can be successfully applied to determine the content of amoxicillin in capsules and tablets with satisfactory results.


Xu X.,Kunming University of Science and Technology | Geng W.,Kunming Productivity Promotion Center | Song J.,Kunming University of Science and Technology | Yang Y.,Kunming University of Science and Technology | Liu M.,Kunming University of Science and Technology
Asian Journal of Chemistry | Year: 2011

A new adsorbent for heavy metal ions removal was obtained by modifying bagasse with epichlorohydrin and cysteine. Bagasse was reacted with epichlorohydrin then grafted with cysteine to produce modified-bagasse. Adsorption behaviours of original-bagasse and modified-bagasse for Cd 2+ and Cu2+ were studied. The cysteine modification was effective at introducing carboxyl and sulfhydryl groups into bagasse. SEM, XPS and FTIR were used to determine the characteristics of original-bagasse and modified-bagasse. The results showed that modified-bagasse had a porous and loose surface covered with carboxyl and sulfhydryl groups, which was beneficial to removing Cd2+ and Cu2+ from wastewater. In the range of experiments, modified-bagasse can reach a maximum saturated adsorption capacity (Qmax) of 1.092 and 1.122 mmol/g, compared with 0.233 and 0.272 mmol/g of original-bagasse for Cd2+ and Cu2+ at 25 °C, respectively. Lower temperature was favourable for the process of adsorption of modified-bagasse. The results indicated that the adsorption property of modified-bagasse had been enhanced obviously, which could be utilized as a potential and promising metal ion adsorbent.


Zou Y.,Kunming University of Science and Technology | Geng W.,Kunming Productivity Promotion Center | Liu M.,Kunming University of Science and Technology | Yang Y.,Kunming University of Science and Technology
Asian Journal of Chemistry | Year: 2011

In presence of the HOAc-NaOAc buffer solution and heating condition, leucomalachite green (LMG) can reacts with I3- to form an ionassociation complex. It made a significant enhancement of resonance Rayleigh scattering (RRS), second-order scattering (SOS) and frequency doubling scattering (FDS). The increments of scattering intensity (DI) were directly proportional to the concentration of leucomalachite green in a certain range. The detection limits were 1.2 ng mL-1 for resonance Rayleigh scattering method, 1.5 ng mL-1 for second-order scattering method and 1.5 ng mL-1 for frequency doubling scattering method, respectively. This result indicates that these methods exhibited high sensitivities. And they were simple and feasible. Three new highly sensitive and simple methods of determination leucomalachite green have been developed. With the reducing action of potassium borohydride, over 85 % of malachite green (MG) can be converted to leucomalachite green. So these can be applied to determine the malachite green in aquatic products.


Li Z.,Kunming University of Science and Technology | Yu G.,Kunming Productivity Promotion Center | Song J.,Kunming University of Science and Technology | Wang Q.,Kunming University of Science and Technology | And 2 more authors.
Water Science and Technology | Year: 2013

A new, simple and rapid method based on dispersive liquid-liquid microextraction (DLLME) was developed for extracting and preconcentrating copper (Cu), nickel (Ni), lead (Pb) and cadmium (Cd) in water samples prior to flame atomic absorption spectrometry (FAAS) analysis. 1-(2-thiazolylazo)naphthol (TAN) was used as chelating reagents, and non-ionic surfactant Triton X-114 and CCl4 as disperser solvent and extraction solvent, respectively. Some influential factors relevant to DLLME, such as the concentration of TAN, type and volume of disperser and extraction solvent, pH and ultrasound time, were optimized. Under the optimal conditions, the calibration curve was linear in the range of 10-800 μg L-1 for Cu and Ni, 10-500 μg L-1 for Pb, and 10-1,000 μg L-1 for Cd, respectively. The limits of detection for the four metal ions were below 0.5 μg L-1, with the enhancement factors of 105,66,28 and 106 for Cu, Ni, Pb and Cd, respectively. The relative standard deviations (RSD, n = 6) were 2.6-4.1%. The proposed method was applied to determination of Cu, Ni, Pb and Cd in water samples and satisfactory relative recoveries (93.0-101.2%) were achieved. © IWA Publishing 2013.

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