Papers by Keyword: Determination

Abstract: The paper presents a novel method for the flotation separation of Cu²⁺ using microcrystalline adsorption system and the determination of trace Cu²⁺ in water samples by spectrophotometry. The effects of the dosages of KI, ascorbic acid (AA) and cetyl pyridinium chloride (CPC),various salts and acidity on the flotation yield of Cu²⁺ have been investigated. The possible flotation separation mechanism of Cu²⁺ was discussed.The results showed that under the optimum conditions, CPC cation (CPC⁺) reacted with I^- to produce the microcrystalline matter (Ms-M) of (CPC⁺·I^-),Cu²⁺ could be reduced to Cu⁺ by ascorbic acid,and then Cu⁺ reacted with I^- to form the precipitation of CuI.The precipitation of CuI was quantificationally adsorbed on the surface of Ms-M of (CPC⁺·I^-) and was floated above salt-water phase. While Zn²⁺、Ni²⁺、Co²⁺、Mn²⁺ and Fe²⁺ could not be floated.Therefore, Cu²⁺ was separated completely from the above metal ions. The proposed method has been successfully applied to the determination of trace Cu²⁺ in various environmental water samples after flotation separation using microcrystalline adsorption system, and the results agreed well with those obtained by GFAAS method.The recoveries were 97.9%~100.7%, and the RSD is 0.8%~1.3%.

Abstract: To examine the extraction method and chromatographic conditions that affect the determination of cinnamaldehyde in Baoyuanqingxue granules and make clinical evaluation about the determination of cinnamaldehyde.Ultrasonic methanol extraction was used before the detemination of cinnamaldehyde in Baoyuanqingxue granules. High Performance Liquid chromatography (HPLC) method was applied to detect samples. The SB-C18 column (Agilent, ZORBAX, 4.6×150mm, 5μm) was adopted, the mobile phase was acetonitrile-water (35:65) at the flow rate of 1.00mL•min-1 with DAD detection wavelength at 290nm, the volume of injection was 20μL and the column temperature was 30°C. The resolution between cinnamaldehyde and other peaks was good. The calibration curve was linear in the range of 0.5035~50.35μg•mL-1(r=0.99976). The average recovery (n=6) of cinnamaldehyde was 99.2% with RSD of 0.5%. The HPLC-DAD method to detect the content of cinnamaldehyde in Baoyuanqingxue granules is simple and accurate. It can be used for quality control of cinnamaldehyde in Baoyuanqingxue granules.

Abstract: A novel and sensitive method has been successfully developed for quantitative detection of invA gene of Salmonella. The surface of sensor chip was modified and then target sequence and probe-2 were induced, which formed a sandwich structure. Under optimal conditions, the SPR-based DNA sensor displayed a linear range of 200 pM - 10 nM and a low detection limit of 200 pM for synthetic target sequence. The excellent sensitivity and high stability of the designed biosensor, make this strategy a promising tool for Salmonella screening.

Abstract: A new fluorescent reagent, 2-hydroxy-1-naphthaldehydene-p-aminotoluene, was synthesized. The fluorescent reaction of this reagent with molybdenum was studied. Based on this chelation, a highly sensitive spectrofluorimetric method was developed for determination of trace amounts of molybdenum in a water-ethanol medium at pH 6.8. Under these conditions, the Mo-HNA complex has excitation and emission maxima at 300 and 380 nm, respectively. The linear range of the method is 0-2μg/L and the detection limit is 0.62μg/L. Interference of other ions was studied. It is necessary to remove the interfering cations through cation exchange. The procedure can be carried out easily and affords good precision and accuracy. This method has been successfully applied to the determination of molybdenum in pig liver and mussels.

Abstract: The compounds, which extracted from Equisetum arvense, Crataegus pinnatifida Bunge, Rosa maximowicziana Regel and Physalis alkekengi, were selected to determine the content of flavonoids and polysaccharides by a visible light spectrophotometry, and the antioxidant activity was determined by a chemical method. The results showed that the content of flavonoids in our compounds was 0.204 mg/g and the polysaccharides was 2.498 mg/g. In scavenging experiments, the levels of hydroxyl radicals and superoxide anion were lower compared with negative control, but the levels were still higher than positive control. The ability to scavenge superoxide anion was more powerful than hydroxyl radicals. This determined that our compound preparation extract have the ability to scavenge hydroxyl radicals and superoxide anion.

Abstract: Under the actions of dissolved oxygen, temperature, electric field, electric arc, moisture, impurities and metal catalysts, transformer oil in operation will undergo oxidation and cracking, which may result in production of large quantities of peroxides, alcohols, aldehydes, ketones and acids. To improve the oxidation stability of oil, the antioxidants should be added into the transformer oil before operation. This paper mainly introduced the oxidation process of transformer oil, the harm of transformer oil oxidation and the method for the determination of the T501 antioxidants content in transformer oil. It also forecast the development trend of the electrochemical test in the determination of T501 antioxidants content.

Abstract: Abstract: In this study we present a method for the determination of free polyethylene glycol in a gel. We detect the PEG residues of cross-linked sodium hyaluronate gel by spectrophotometry. The pretreatment of cross-linked sodium hyaluronate gel is special and the plot of working curve is unconventional. The precision, the recovery rate with marker, the reliability and repeatability of this method are tested and verified. The results indicated that the method has an excellent linear relationship in the range of 0-40.5µg mL^-1. The regression equation is Y=0.0108X+0.2047 (R2=0.9994). The standard deviation of the detection method is 1.10% (n=9). The recovery rate with marker is 97.8% and the repeatability is perfect. In conclusion, the method possesses the properties of simple operation, quickness, excellent stability. Moreover this method can be applied for the quality control of gel products cross-linked by PEG and liquid samples containing PEG.

Abstract: A specific, sensitive, and reliable analytical method involving homogenate extraction, solid phase extraction (SPE), and detection by high-performance liquid phase chromatography electrospray tandem mass spectrometry was developed in this study for the determination of triclocarban (TCC) in aquatic plants. Key factors that could affect the extraction, including the extraction solvent and its volume, the length of time of homogenate extraction, were examined and optimised. Under optimum conditions, the linearity of the method ranged from 0.2 ng/g to 200 ng/g, with correlation coefficients (r²) >0.999. The limit of detection was 0.05 ng/g, based on the ratio of the chromatographic signal to baseline noise (S/N = 3). Spiked recoveries of TCC in real aquatic plant samples ranged from 91.8% to 106.1%. The proposed method was successfully applied to analyse TCC in aquatic plant samples collected from a natural water environment.

Abstract: The paper presents a novel method for the flotation separation of Cu²⁺ using microcrystalline adsorption system and the determination of trace Cu²⁺ in water samples by spectrophotometry. The effects of different parameters,such as the dosages of KI, ascorbic acid (AA) and cetyl trimethyl ammonium bromide (CTMAB),various salts and acidity on the flotation yield of Cu²⁺ have been investigated. The possible flotation separation mechanism of Cu²⁺ was discussed.The results showed that under the optimum conditions, CTMAB cation (CTMAB⁺) reacted with I^- to produce the microcrystalline matter (Ms-M) of (CTMAB⁺·I^-), Cu²⁺ could be reduced to Cu⁺ by ascorbic acid,and then Cu⁺ reacted with I^- to form the precipitation of CuI.The precipitation of CuI was quantificationally adsorbed on the surface of Ms-M of (CTMAB⁺·I^-) and was floated above water phase. While Zn²⁺,Ni²⁺,Co²⁺, Mn²⁺, Fe²⁺ and Al³⁺ could not be floated.Therefore, Cu²⁺ was separated completely from the above metal ions. The proposed method has been successfully applied to the determination of trace Cu²⁺ in various environmental water samples by spectrophotometry after flotation separation using microcrystalline adsorption system, and the results agreed well with those obtained by GFAAS method.The recoveries were 98.4%~106.8%, and the RSD was 1.1%~1.6%.

Abstract: High performance capillary electrophoresis (HPCE) was used in this text to determine the content of ferulic acid in “SHI-QUAN-DA-BU” Pills. Electrophoretic separation conditions: Uncoated fused silica capillary column(75um×49/58cm), injection height 7.5cm, 30mmol•L^-1 borax solution, separation voltage 20kV, injection time 15s, detection wavelength 315 nm, experimental temperature 20°C. Linearity was kept in the concentration ranging from 1~31.25 mg·L^-1 of ferulic acid with correlation coefficient of 0.970. The average recovery was 97.56% and RSD value was 6.4%. The content of ferulic acid was 0.0855 mg/g (n=6).