Tạp chí Phân tích Hóa, Lý và Sinh học

    Pyrolusite ore from Cao Bang province was denatured to adsorb fluoride in waste water.There were 3 methods studied for denaturing Pyrolusite in this paper to be: temperature,HNO3 acid and Al2 (SO4)3. The method using HNO3 acid (0,5 M, shaking time for 4 hours) wasthe best for denaturing Pyrolusite (adsorbing efficiency: 44 %; adsorbing capacity: 0.15mg/kg). The best conditions for adsorbing fluoride of denatured Pyrolusite were pH to be 2and shaking time to be 4 hours.Two waste water samples were applied to investigate fluoride adsorbed ability of denaturedPyrolusite. The efficiency for adsorbing fluoride ranged from 16.9 to 19.6 % and adsorbingcapacity was 0.12 mg/kg.Keywords: Denatured Pyroluxite ore, adsorb, fluoride, waste water

    This paper developted a method for the identification and quantification of phenol and intermediate products of phenol ozonation include hydroquinone, catechol, benzoquinone in aqueous using High Performance Liquid chromatography (HPLC) analysis. Optimum conditions for analysis have been investigated. Chromatographic separation was performed by a reversed phase C18 column with a mobile phase consisting of methanol and aqueous 0.1% phosphoric acid in a ratio (10:90). The calibration curves showed excellent coefficients of determination (R2 ≥ 0.999) within the concentrations tested. The recoveries were 87.92% to 99.25% for spiked samples.Keywords: phenol, catechol, benzoquinone, hydroquinone, HPLC

A method based on ultra high performance liquid chromatography coupled with tandem mass spectrometry (UPLC/MS/MS) as development for simple and rapid determination of the residues of tinopal CBS - X in rice products. The sample were extracted by 4 % phosphoric acid in acetonitrile and then analyzed in multiple reaction monitoring (MRM) mode. The mobile phase was composed of solvent A (water) and solvent B (acetonitrile). Gradient program was performed as follows: 0 - 0.5 min, 80% A; 0.5 - 4.0 min, 20% A and at initial condition. Total run time is 8 min. The flow rate was settled at 0.3 ml/min with an injection volume of 10 μl. Under the optimized conditions, the linear range for tinopal CBS - X is 1.0 – 10 ng/g, the linear correlation coefficients are more than 0.99. The limits of quantification of tinopal CBS - X are 2.20 ng/g. The recoveries of tinopal CBS - X ranged from 93.50 % - 118.3 % with relative standard deviation (RSD) between 0.96 – 12.06 %. The method was validated according to the Directive 2002/657/EC and subsequently applied to 18 samples of rice products.

Development of an effective electrochemical sensor for the sensitive detection of antibiotics in food, pharmaceutical formulations and biological liquids is of current interest. We have looked at possibility of rapid detecting sulfamethoxazole (SMZ), an antibiotic of the sulfonamide family, using a composite of reduced graphene oxide, polydopamine and copper nanoparticles as a modified electrode. The important parameters for synthesis of the composite were identified. Using the modified sensor, linear range of SMZ concentration is 4 - 80 μM, with R2 = 0,9893 and LOD of 1.12 M. Furthermore, the modified electrodes were used for the examination of the SMZ content in a commercial product, with reasonable recover

The present work deals with the study of Nd-doped CoFe2O4 samples, which were prepared by a solution combustion method. The obtained samples were characterized by powder X-ray diffraction (XRD), scanning electronmicroscopy (SEM), transmission electronic microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray analysis, UV-Visible diffuse reflectance spectra (DRS). The effect of Nd3+ ions substitution on the structural, optical and photo-Fenton activity of CoNdxFe2−xO4 has been investigated. The addition of Nd3+ ions caused a decrease in the grain size of ferrites, the reduction of the optical bandgap energies and thus could be well exploited for the catalytic study. The photocatalytic activity of the synthesized CoNdxFe2-xO4 nanoparticles is investigated by using Rhodamine B dye under visible light and presence of H2O2. The efficiency of photocatalytic activity of cobalt ferrite increases with increase in Nd-doping. Due to effective separation and inhibition of e-/h+pair recombination, relatively higher photocatalytic of RhB was achieved for CoNdxFe2-xO4 (x = 0.01 ÷ 0.05) when compared to CoFe2O4. The first order rate constant for CoNdxFe2-xO4 (x = 0.01 ÷ 0.05) is faster than CoFe2O4.

Chlorogenic acids (CGAs) constitute a large family of esters and are present in many medicinal plants. CGAs play an important role in modern traditional medicine, but only some of this family’s pure compoundshave been thoroughly researched and shown good pharmaceutical effects. The green coffee beans (CFX)contained ~ 11% of CGAs depending on the species, cultivation and harvested conditions. The quatitativeanalysis could show the presence of separate CGA compounds. Instead of using expensive pure CGA compounds as analysis standard, the HRMS-QTOF detector could unequivocally assign the compound identity while the coupled HPLC could effectively separate the CGAs . In this study, the HPLC-QTOF technique was used to qualitatively determine the CGAs present in the green coffee beans. Ít showed that the CFX harvested in different times have the same CGAs profiling.

Công trình này khảo sát các đặc trưng của hiện tượng nhiễm bẩn màng lên hiệu quả hoạt động của hệ thống khử mặn trên cơ sở công nghệ lọc thẩm thấu xuôi sử dụng chất lôi cuốn Polyvinylpyrrolidone K17, thông qua đánh giá sự thay đổi của giá trị thông lượng nước thẩm thấu qua màng và giá trị thông lượng chất lôi cuốn thẩm thấu ngược qua màng, cũng như ảnh chụp kính hiển vi điện tử quét (SEM). Kết quả khảo sát cho thấy, tồn tại những khác biệt đáng kể giữa tác nhân gây nhiễm bẩn tại phía bề mặt màng bán thấm tiếp xúc với dung dịch cần xử lý và tác nhân gây nhiễm bẩn tại phía bề mặt màng bán thấm tiếp xúc với dung dịch lôi cuốn. Bên cạnh đó, kết quả so sánh hiệu quả làm sạch giữa phương pháp rửa xuôi và phương pháp rửa ngược cũng giúp chứng minh sự tồn tại của tình trạng nhiễm bẩn xảy ra trong cấu trúc màng bán thấm. Điều này nhấn mạnh sự cần thiết của việc phải xác định được những phương pháp làm sạch mới nhằm cải thiện khả năng vận hành lâu dài và ổn định cho các hệ thống khử mặn trên cơ sở công nghệ lọc thẩm thấu xuôi sử dụng chất lôi cuốn Polyvinylpyrrolidone K17.xuôi sử dụng chất lôi cuốn Polyvinylpyrrolidone K17

The reverse phase - high performance liquid chromatography (RP-HPLC) method was developed to simultaneously determine three carotenoids, including lutein, lycopene, and β-carotene, in orange juice. Orange juice was extracted with n-hexane for 10 minutes, centrifuged for 5 minutes at 6000 rpm, and then evaporated under vacuum. A volume of 5 mL of the mobile phase was added, filtered through filter paper, and injected into the HPLC-PDA system under the following conditions: XBridge® C18 column (250 mm x 4.6 mm, 5 µm), mobile phase consisting of a mixture of acetonitrile: methanol: water: ethyl acetat = 70:9.6:0.4:20 (v/v/v/v) according to an isocratic program, detection wavelength 455 nm. The calibration curves for lutein, lycopene, and β-carotene determination had R² coefficients > 0.9997, and the validation parameters met AOAC standards. The method detection limits for lutein, lycopene, and β-carotene were 0.002 mg/L, 0.003 mg/L, and 0.006 mg/L, respectively. The validated method was applied to simultaneously determine lutein, lycopene, and β-carotene in 45 Vietnamese orange juice samples. Lycopene was not detected in the Vietnamese orange samples. The content of lutein and β-carotene varied depending on the orange variety and region. The β-carotene content in Citrus nobilis was much higher than in the other orange varieties in this study. The minimum and maximum contents of lutein in the collected samples were 0.018±0.008 mg/L and 0.221±0.039 mg/L, respectively, whereas these values for β-carotene content were 0.020±0.009 mg/L and 0.423±0.099 mg/L, respectively.

Schweinfurthin G, a stilbenoid, was originally identified and isolated from Macaranga alnifolia, which were also isolated from Macaranga tanarius growing in Vietnam in high yield. This compound exhibited a strong cytotoxicity against A549 and KB cell lines with the IC50 values of 0,80 μM and 0,6 μM, respectively. However, there are few papers reporting about total synthesis of this derivative. In this paper, we reported the synthesis of a new diamide derivative of schweinfurthin G from schweinfurthin G through six reaction steps and this compound exhibited a strong cytotoxicity against KB cancer cell line with an IC50 value of 4,4 μM.

In this article, SiO2 material was synthesized by sol-gel method in acidic environment and CeO2 material coated with SiO2 (CeO2@SiO2) was synthesized in alkaline environment. The structure of the powder was characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) was used to characterize the samples. The size of SiO2 and CeO2@SiO2 materials were uniform, small and the particles were distributed from 10 to 30 nm. The study showed that the adsorption capacity of NH4+ ions was consistent with the Langmuir adsorption isotherm model, the adsorption capacity of NO3 - was consistent with the Freundlich isotherm model. The research results showed that nano silica material made from rice husks has the ability to adsorb NH4+ and NO3- ions in aqueous environment. It is intended to be used in fertilizer products, supporting the immediate need for nitrogen for plants. fertilizer products, supporting the immediate need for nitrogen for plants.