Papers by Keyword: Determination

Abstract: The paper presents a novel method for the separation/enrichment of trace Co2+ using microcrystalline phenolphthalein modified with 8-hydroxyquinoline (HQ) prior to the determination by spectrophotometry. The effects of different parameters,such as the dosages of phenolphthalein and HQ,various salts and acidity on the enrichment yield of Co2+ have been investigated to select the experimental conditions. The possible enrichment mechanism of Co2+ was discussed.The results showed that under the optimum conditions, Co2+ could be quantificationally adsorbed on the surface of microcrystalline phenolphthalein in the form of the chelate precipitate of Co(HQ)2 ,while K+,Na+,Ca2+,Mg2+,Cd2+,Zn2+,Mn2+,Fe2+ and Al3+ could not be adsorbed at all.Therefore,Co2+ was completely separated from the above metal ions in the solution. A new method for the spectrophotometric determination of trace cobalt after separation/enrichment using microcrystalline phenolphthalein modified with 8-hydroxyquinoline was established.The proposed method has been successfully applied to the determination of Co2+ in various environmental water samples, and the results agreed well with those obtained by FAAS method.

Abstract: The oxidation of phenanthrene, with peracetic acid and by means of reaction distillation, into 2,2’-diphenic acid, and determination of phenanthrene, phenanthrenequinone and diphenic acid in the oxidation reaction mixtures, with a HPLC, have been studied. For the determination of phenanthrene, phenanthrenequinone and diphenic acid, the experimental results showed that the concentrations of the three components and their corresponding peak area presented good linear relationship. And for the oxidation, main technical parameters optimized by orthogonal test. The optimum conditions were as follows: molar ratio of phenanthrene to acetic acid: 1.0:25.0; molar ratio of phenanthrene to H2O2: 1.0:8.0; dropping time of 30%H2O2: 9h; reaction time:18h；solvent: benzene; reaction temperature: about 90°C(boil).

Abstract: A sensitive method for the simultaneous determination of TCC and TCS in water, which involves enrichment with SPE and detection with HPLC-ESI-MS, was developed. The influence of the operational parameters,such as eluan, the acidity of the sample, were investigated and optimized. Under the optimum conditions, the limits of detection were 1.0 ng L-1and 2.5 ng L-1 for TCC and TCS, respectively. The method was successfully applied to the analysis of triclocarban and triclosan in real environmental water samples, including river water, lake water and tap-water. The spiked recoveries of TCC and TCS in these samples were achieved in the range of 89.5%–97.5%.

Abstract: This article mainly aims at the frame structure seismic identification and reinforcement, and example analyzed a middle school building structure of the framework aseismatic appraisal and reinforcement.

Abstract: In this study, our purpose was to establish a UPLC method for the simultaneous determination of Paeoniflorin and Paeonol in Houyinan Tablet. The separation was performed on Acquity BEH C18 column(2.1mm×100mm,1.7μm), the mobile phase was acetonitrile-water with gradient elution at a flow rate of 0.2 mL•min-1, the detection wavelength was 230nm, the column temperature was 30°Cand the injection volume was 2μL. Paeoniflorin and Paeonol reached effective separation with the other components in this chromatographic conditions. Paeoniflorin and Paeonol were linear within the range of 0.0406~0.4064μg(r=0.9999) and 0.0426~0.4256μg (r=0.9999), respectively. The average recovery was 99.82% and 100.6%. The results of method validation indicated that the method was simple,quick,accurate, specific and less solvent consumption. It can be used for the quality control of Houyinan Tablet.

Abstract: Objective: To establish a determination method for gliotoxin. Methods: Reverse-phase high performance liquid chromatography (HPLC) method was used：the column was Inertsil ODS-SP; detection wavelength set at 254 nm; mixed solution of menthol and water（50:50）was used as the mobile phase with flow rate of 1.0 mL/min. Results: The regression equation of gliotoxin content was y = 9E–08x–0.003. The linear range was 0.5-2.5mg/mL and the average recovery was 99.22%. Conclusion: This method is simple, effective and suitable for analysis of the gliotoxin. A reliable basis was provided for the determination of gliotoxin.

Abstract: A novel application of carbon nanotubes (CNTs) in the field of chromogenic reactions for recognizing aminophenol isomers was described. Among the three of aminophenol isomers, only p-aminophenol could form the chromogenic system. Comparative experiments proved that the absorption of the complex increased by 23.9% in the presence of CNTs due to the presence of the intact conjugated system. A selective determination of p-aminophenol was obtained

Abstract: The lactic acid bacteria to produce GABA and GABA determinations method were studied. Research results show that the strains isolated belong to Lactobacillus delbruckii for GABA with morphological and physiological and biochemical characterization. Paper chromatography for determination of GABA, which suitable conditions for developing agent (N-butanol: acetic acid: water) volume ratio were 4: 1: 3, under 30 min, 80 °C, 510nm detection wavelength respectively.

Abstract: Pumpkin is a widely cultivated vegetable used for human consumption and traditional medicine this investigation will provide much more information for the further exploration of pumpkin seeds. In the present study, the contents of total phenolics, phytosterols, squalene, α-tocopherol, polysaccharides and γ-aminobutyric acid (GABA) from the five types of pumpkin seeds cultivars were determined by established methods. The total phenolics contents of the pumpkin seeds ranged from 0.96 to 2.52 mg/g, total phytosterols contents ranged from 2.02 to 2.65 mg/g, while the levels of squalene and α-tocopherol detected ranged from 0.92 to 1.29 mg/g and 83.09 to 98.57µg/g, respectively. Polysaccharides were the most abundant constituents, ranging in concentration from 119.42 to 143.77 mg/g, GABA was also present in significant concentrations ranged from 3.71 to15.53 mg/g. Results indicated that bioactive ingredients from Baoku1 exhibited the relatively higher values in all the cultivars.

Abstract: Chitosan is a natural basic polysaccharide, currently which have no a very effective way to determine its content. In this paper, we used mixed acid and ultrasound-assisted with chitosan which hydrolyzed into glucosamine, under alkaline condition acetyl acetone may react with paradimethylaminobenzaldehyde acid alcohol solution to form red compound, which was measured at 525nm by spectrophotometry. More appropriate technological conditions have been determined. The results showed that the optimal conditions for quantity of chitosan was 2mg, 0.168mol/L hydrochloric acid was 0.8ml, 75% sulfuric acid was 3.5ml, in boiling water bath for 30min, supersonic for 60min at 50 °C, the average recovery was 96.9±3.24%, the content of chitosan was 87.89±1.02%, the production rate of chitosan was 84.79±0.99%. The results show that the mentioned method is easy and effective for the quantitative analysis of chitosan by spectrophotometry.