Fengshan Yu

Development of Cloud Point Extraction for Simultaneous Extraction and Determination of Platinum and Palladium Using Inductively Coupled Plasma Optical Emission Spectrometry in Platinum-Palladium Spent Catalysts

A new on-line cloud point extraction system coupled to inductively coupled plasma optical emission spectrometry was designed for simultaneous extraction, preconcentration and determination of trace amounts of platinum and palladium in platinum-palladium spent catalysts. This was based on the complexation of the metal ions with 1,8-diamino-4,5-bis(hydroxyamino)anthraquinone reagent in the presence of non-ionic surfactant of Triton X-114. After phase separation, the surfactant-rich phase was diluted with concentrated HNO3 (70%, w/w); the analytes concentrations were determined by inductively coupled plasma-optical emission spectrometry. Several factors influencing the instrumental conditions and extraction were evaluated and optimized. Under the optimum conditions, the enhancement factors of the proposed method were 35.4 and 29 for platinum and palladium, respectively. The detection limits were 0.3 and 0.45 µ g L−1. Finally, the developed method was successfully applied to the extraction and determination of platinum and palladium in platinum-palladium spent catalysts samples and satisfactory results were obtained.

Fluorescence enhancement effect for the determination of DNA with calcein–cetyl trimethyl ammonium bromide system

A new spectrofluorimetric method was developed for the determination of trace amounts of DNA using the calcein as a fluorescent probe. In the presence of appropriate amounts of the cationic surfactant cetyl trimethyl ammonium bromide (CTAB), the anionic dye calcein dimerizes. The weak fluorescence intensity of the dimer was enhanced by adding DNA at pH 6-7. The interaction between calcein-CTAB and DNA was studied on the basis of this behavior and a new method was developed for determining DNA. Under the optimal conditions, the enhanced fluorescence intensity was in proportion to the concentration of DNA in the range of 4.0x10(-6) to 8.0x10(-5) g L(-1) for fsDNA and thermally denatured ctDNA (4.5x10(-6) to 9.0x10(-5) g L(-1)). The detection limits (S/N=3) were 2.0x10(-6) and 2.2x10(-6) g L(-1), respectively. This method was used for determining the concentration of DNA in synthetic samples with satisfactory results.

Sensitive Determination of Prulifloxacin by Its Fluorescence Enhancement on Terbium(III)-Sodium Dodecylbenzene Sulfonate System

Abstract A terbium-sensitized fluorescence spectrophotometry method using an anionic surfactant, sodium dodecyl benzene sulphonate (SDBS), was developed for the determination of prulifloxacin (PUFX). It was found that SDBS significantly enhanced the fluorescence intensity of the PUFX–Tb3+ complex (about 13-fold). The optimal experimental conditions were determined as follows: excitation and emission wavelengths of 290 nm and 545 nm, pH 8.0, 4.0 × 10−5 mol L−1 terbium(III), and 4.0 × 10−4 mol L−1 SDBS. The enhanced fluorescence intensity of the system (ΔF) showed a good linear relationship with the concentration of PUFX over the range 6.0 × 10−8 to 2.0 × 10−6mol L−1 with a correlation coefficient of 0.9991. The detection limit (S/N = 3) was determined as 8.5 × 10−9 mol L−1. This method has been successfully applied for the determination of PUFX in pharmaceuticals and human urine/serum samples. Compared with most other methods reported, the rapid and simple procedure proposed here offered higher sensitivity, wider linear range, and good stability. The luminescence mechanism of the system was also discussed in detail. In the fluorescence system of PUFX–Tb3+–SDBS, SDBS acted not only as the surfactant but also as the energy donor.

A Direct Chemiluminescence Method for the Determination of Prulifloxacin Using Tris-(4,7-Diphenyl-1,10-Phenanthrolinedisulfonic Acid) Ruthenium(II)–Cerium(IV) System

Abstract A simple, rapid, injection chemiluminescence method is described for the determination of prulifloxacin, a commonly used antibiotic. A strong chemiluminescence signal was detected when a mixture of the analyte and tris-(4,7-diphenyl-1,10-phenanthrolinedisulfonic acid)ruthenium(II) was injected into cerium(IV) sulfate. The chemiluminescence signal is proportional to the concentration of prulifloxacin in the range 4.0 × 10−8–9.0 × 10−6 mol L−1. The detection limit is 1.0 × 10−8 mol L−1, and the relative standard deviation is 2.2% (n = 11) for the determination of 8.0 × 10−7 mol L−1 prulifloxacin. The proposed method was successfully applied to the determination of prulifloxacin in pharmaceutical preparations in capsules, spiked serum, and urine samples.

Flow-Injection Chemiluminescent Determination of Piroxicam Using Tris (2,2′-bipyridyl) Ruthenium(II)—Potassium Permanganate System

Abstract A rapid and sensitive chemiluminescence method using flow-injection has been developed for the determination of an analgesic agent drug, piroxicam. The method is based on the chemiluminescence reaction of piroxicam with an acidic potassium permanganate and Ru(bipy)3 2+. The chemiluminescence intensity is greatly enhanced when quinine sulfate is used as a sensitizer. After optimization of the different experimental parameters, a calibration graph was obtained over a concentration range of 3.0 × 0−8–3.0 × 0−5 mol L−1 with the detection limit of 1.0 × 0−8 mol L−1. The relative standard deviation is 1.5% (n = 11) for the determination of 8.0 × 10−7 mol L−1 piroxicam. The proposed method was successfully applied to commercial tablets, spiked serum, and urine samples.

Chemiluminescence method for the determination of piroxicam by the enhancement of the tris-(4,7-diphenyl-1,10-phenanthrolinedisulphonic acid) ruthenium(II) (RuBPS)-cerium(IV) system and its application.

A simple, rapid chemiluminescence (CL) method was described for the determination of piroxicam, a commonly used analgesic agent drug. A strong CL signal was detected when cerium(IV) sulphate was injected into tris-(4,7-diphenyl-1,10-phenanthrolinedisulphonic acid) ruthenium(II) (RuBPS)-piroxicam solution. The CL signal was proportional to the concentration of piroxicam in the range 2.8 x 10(-8)-1.2 x 10(-5) mol/L. The detection limit was 2 x 10(-8) mol/L and the relative standard deviation (RSD) was 3.7% (c = 7.0 x 10(-7) mol/L piroxicam; n = 11). The proposed method was applied to the determination of piroxicam in pharmaceutical preparations in capsules, spiked serum and urine samples with satisfactory results.

Highly Sensitive Spectrofluorimetric Determination of Trace Amounts of Superoxide Dismutase Using a Prulifloxacin-Terbium(III) Probe

Abstract A new spectrofluorimetric method was developed for determining superoxide dismutase. The interactions between prulifloxacin (PUFX) –Tb3+ complex and superoxide dismutase had been studied by using UV-Vis absorption and fluorescence spectra. Using prulifloxacin–Tb3+ as a fluorescence probe, under optimum conditions, superoxide dismutase could remarkably enhance the fluorescence intensity of the prulifloxacin–Tb3+ complex at λ = 545 nm, and the enhanced fluorescence intensity was in proportion to the concentration of superoxide dismutase. Optimum conditions for the determination of superoxide dismutase were also investigated. The dynamic range for the determination of superoxide dismutase was 0.032 to 22.56 µg mL−1, and the detection limit (S/N = 3) was 1.5 ng 4 mL−1. This method was simple, practical, and relatively free of interference from coexisting substances and could be successfully used to determine superoxide dismutase in the plant and blood samples. The mechanism of fluorescence enhancement of prulifloxacin–Tb3+ complex by superoxide dismutase was also discussed.

Molecular Imprinting-Chemiluminescence Sensor for the Determination of Prulifloxacin

Abstract A selective molecular imprinting-chemiluminescence sensor is developed for the determination of prulifloxacin by using a prulifloxacin-imprinted polymer as recognition material and the cerium(IV)/sodium thiosulfate/prulifloxacin chemiluminescence reaction as the detection system. The linear response range of the sensor is from 8.0 × 10−8 to 7.0 × 10−6 mol L−1 with a detection limit of 2.0 × 10−8 mol L−1. The relative standard deviation for 5.0 × 10−7 mol L−1prulifloxacin solution is 1.3% (n = 7). This sensor has been applied to the determination of prulifloxacin in urine samples, and the results obtained are satisfactory.

Highly Sensitive Spectrofluorimetric Determination of Trace Amounts of Folic Acid using a Oxytetracycline-Terbium(III) Probe

Abstract A new spectrofluorimetric method was developed for the determination of trace amounts of folic acid using oxytetracycline–terbium ion complex as a fluorescent probe. In the buffer solution of pH 6.00, folic acid remarkably reduced the fluorescence intensity of the oxytetracycline–terbium complex at λ = 545 nm. The reduced fluorescence intensity of the Tb3+ ion was proportional to the concentration of folic acid. Optimum conditions for the determination of folic acid were investigated. This method was simple, practical, and relatively free of interference from coexisting substances. Furthermore, it was successfully applied to assess folic acid in tablet, injection, and urine samples.

Fluorescence Probe Enhanced Spectrofluorimetric Method for the Determination of Prulifloxacin in Pharmaceutical Formulations and Biological Fluids

Abstract Spectrofluorimetry for the determination of prulifloxacin (PUFX) was developed based on the strong fluorescence of PUFX after adding fluorescence probe yttrium in buffer solution (pH = 6.80), and various factors of influencing fluorescence have been researched. Under the optimum conditions, the liner range was 2.0 × 10−8 to 9.1 × 10−6 mol L−1 and the detection limit was 8.5 × 10−9 mol L−1. The relative standard deviation was 2.1% for 11 measurements of 5.0 × 10−7 mol L−1 PUFX standard solution. The mechanism of the sensitizing effect of probe was discussed. The method was applied for the determination of PUFX in actual sample; the result obtained was satisfactory.