Tạp chí Phân tích Hóa, Lý và Sinh học

Nghiên cứu kết tinh chọn lọc cấu trúc tinh thể amino acid glycine chất lượng cao đạt chuẩn dược điển của Mỹ (FDA) và Châu Âu (EMA) là việc làm cần thiết trong ngành công nghiệp dược trước khi được thương mại hóa trên thị trường thế giới. Trong nghiên cứu này, tinh thể glycine có ba dạng cấu trúc tinh thể khác nhau gồm α-glycine, β-glycine và γ-glycine có thể được hình thành đồng thời trong quá trình kết tinh. Các cấu trúc tinh thể này có độ hòa tan khác nhau nên có hoạt tính sinh học và công thức thuốc khác nhau. Kiểm soát quá trình kết tinh các tinh thể đa cấu trúc rất phức tạp khi phụ thuộc vào nhiều yếu tố công nghệ. Do vậy, nghiên cứu kết tinh chọn lọc cấu trúc tinh thể mong muốn là việc làm đầy thử thách trong ngành công nghiệp dược. Kết quả nghiên cứu cho thấy 100% tinh thể α-glycine được ưu tiên kết tinh tại chế độ thủy động lực 300 rpm, nồng độ ban đầu 300 g/L, tốc độ làm lạnh 5oC/min, và nhiệt độ cuối của quá trình kết tinh 30 oC. Ngược lại hỗn hợp hai cấu trúc tinh thể α-glycine và γ-glycine sẽ được ưu tiên kết tinh tại cùng nhiệt độ cuối 30 oC. Trong khi đó, hỗn hợp hai cấu trúc α-glycine và β-glycine được kết tinh ở nhiệt độ cuối rất thấp khoảng -30 oC.

Aflatoxin is the high toxicity group of mycotoxins that can lead to fatal if acute poisoning or liver cancer if accumulating at low levels in the body. In this study, an ultra-performance liquid chromatography-tandem trip-quadruple mass spectrometry (UPLC-MS/MS) method has been validated for simultaneous determination of aflatoxins group B and G in produced peanut samples. Under optimal experimental conditions, the method detection limit (MDL) for aflatoxin B1 (AFB1) and aflatoxin G1 (AFG1) are 0,1 µg/kg. MDL for aflatoxin B2 (AFB2) and aflatoxin G2 (AFG2) are 0,03 µg/kg. The correlation coefficient (R2) of all calibration lines are 0.999. The average method recovery (%) at three different levels and for all four aflatoxins range from 90,7 to 98%. At different concentrations of aflatoxins, the relative standard deviations (RSD%) of repeatability is lower than 1,1 %, and the intermediate precision is lower 3.8 %. Comparison with the requirements of the Viet Nam Ministry of Health, the validated method is very sensitive and accurate to determine the aflatoxin in peanut product sample, and can be used for quality control and food safety.

Cây bạch đàn rất phổ biến ở Việt Nam và nhiều quốc gia trên thế giới. Tinh dầu bạch đàn được sử dụng rộng rãi trong đời sống hàng ngày với nhiều công dụng hữu ích như điều trị cảm lạnh, ho, kháng khuẩn, trịvết thương do côn trùng cắn, bảo vệ da,… Trong bài báo này, chúng tôi nghiên cứu về thành phần hóa học, hoạt tính kháng khuẩn, kháng oxy hóa của tinh dầu lá và quả bạch đàn thu hái tại Đồng Tháp bằng cácphương pháp khác nhau. Kết quả cho thấy 2 loại tinh dầu có cùng thành phần một số hợp chất chính như αphellandrene, p-cymene, γ-terpinene, α-pinene. Tuy nhiên, eucalyptol, một hợp chất có hoạt tính sinh học mạnh chiếm 4.9% trong tinh dầu lá bạch đàn, lại không hiện diện trong tinh dầu quả. Cả 2 loại tinh dầu đều thể hiện khả năng ức chế 4 dòng vi khuẩn B. cereus, B. subtilis, P. aeruginosa and E. coli và hoạt tính kháng oxy hóa yếu trên gốc tự do DPPH và ABTS•+.

    Abstract: The KOH - modified rejected tea (KRT) was used as a adsorbent to removeefficiently Cr(VI) from aqueous solution in fixed-bed column. Scanning electron microscopy(SEM) images of KRT reveal a highly porous surface structure. Experiments were performedas a function of initial feed of Cr(VI) concentration, particle size, the amount of adsorbent. Atthe time of C = 0,001Co and C = 0,05Co, the maximum bed capacities is 1472.69 mg/L (7.36mg /g), downtime is 0.6526 h and 3917.86 mg/L (19.56mg/g), downtime is 0.6445h;respectively. KRT also was used as a adsorbent to remove efficiently Cr(VI) from waste waterof Minh Khai Lock Company (WWMK). This study indicated that the KRT can be used as aneffective and environmentally friendly adsorbent for the treatment of Cr(VI) ions in aqueoussolutions.Keywords: Adsorption; tea waste, fixed- bed column; heavy metals; KOH- modified rejected tea.

  In this article we have studied on the modification of rice husk with Diphenyl carbazite(DPC) as solid phase extraction material in combination with F-AAS method to determinetraces of Cr. SEM and FTIR results reveal that modified rice husk has small particle size,porous surface, which is attached with DPC molecules. Modified material has highadsorption capacity for both Cr(VI) and Cr(III), and specially high for Cr(VI). Optimumconditions for SPE procedure using this material for Cr enrichment such as pH, sampleloading rate, elution solution, elution rate,. have been investigated. The combination of thisSPE procedure with F-AAS method gives enrichment factor of 20. Analysis of total Cr in theCRM waste water gives high accuracy and precision that satisfy trace analysis requirement.SPE- FAAS method has been applied in determination of total Cr in several industrial wastewater samples taken at Hung Yen industrial park.

Vietnam is a major coffee exporter in the world with an estimated annual output of more than one million tons. From the production of green coffee, a large amount of defective green coffee beans arediscarded. The collection of these defective green coffee beans for medicinal purposes has made full use of natural resources, bringing great value in both economy and environment. The study was carried out with the following methods: Recovering of green coffee extract by impregnating in ethanol; Testing for antimicrobial activity; Syntheticing nano silver - green coffee AgNPs-GCB. The results showed that the high amount of extract obtained from discarded coffee beans reached 28.5-29.1%. Green coffee extract (GCB) has chlorogenic acid (CGA) reaching 6.7%, caffeine 2.7% and could be used in pharmaceutical chemicals and cosmetics. Green coffee extract, in addition to the known traditional medicinal effects, is also a biologically active substance, reducing sugar, a stable emulsifying support system in the production of nano-biomaterials to create nano-AgNPs-GCB for creating added value from waste for coffee production

    The investigation of pollution in the water wells of households living around the industry zone of Phu Hoi, Duc Trong District, Lam Dong Province has been carried out during the years of 2012-2013. The analytical result showed that the concentrations of As, Cd, Pb, Cu, Zn, Fe, Mn in samples of 15 water wells are lower than recommendation of QCVN 08:2008; however the contents of COD, BOD, Coliform, E.Coli in these sample are rather high, higher than that QCVN 08:2008 recommended.

Pomelo peel contains a lot of important bioactive compounds having benefits for human health. This pomelo peel (Citrus grandis L.) products have important health benefits, so pomelo peel tea has been produced in order to enhance this great value. In-vitro and in-vivo studies on Nam Roi pomelo peel tea extract combined with identified acute toxicity in white male mice at a single oral dose of 5000 mg/kg body weight suggests that this is a safe product and has a high antioxidant effect as well as helps reduce the activity of glucose in the blood. This kind of extract had reduced blood sugar to normal levels (126.00±16.89 mg/dL, 100% survival) at a dose of 400 mg/kg weight of male white mice. There was no significant difference with the physiological control mice, which were more effective than those treated with glucophage (187.2±11.87 mg/dL). This extract also exhibited moderate antioxidant activities with EC50 value of 80.81 ± 0.91; 93.61 ± 0.31; 106.52 ± 0017; 114.41 ± 1.01 μg/mL according to ABTS·+, FRAP, RP and DPPH methods, respectively. However, the exception of EC50values up to 349.31 ± 0.14 μg/mL when using the TAC method.

Viologens (V) are electroactive organic molecules bearing typical properties such as structural diversity, high electron transfer, and particularly the redox state dependent colloring. Therefore, study on the photoelectrochemcial properties of viologens is necessary to enlarge their applications in the fields of electrochemical sensing and electrochromics. In this work, we present such research results on the electrochemical properties of viologen molecules including dibenzyl viologen (DBV), diphenyl viologen (DPV) và diethyl viologen (DEV) deposited on indium tin oxide (ITO) in acidic media by cyclic voltammetry (CV) method. The DPV and DBV molecules undergo two subsequent redox processes (V2+ V+ V0), whereas the DEV only involves in single one (DEV2+ DEV+) within the potential range of 0.3 V  1.0 V vs Ag/AgCl (CKCl = 3M). Moreover, impact of the redox states on the optical property of DBV is characterized in detail using in-situ UV-Vis technique. At E = -0.2V vs Ag/AgCl, where the DBV2+ cation exists, the corresponding UV-Vis spectrum shows a featureless behavior. Contrarily, at E = -0.8V and E = -1.0 V vs Ag/AgCl, where the DBV+ and DBV0 moieties are generated, respectively, the corresponding UV-Vis spectra reveal such emerged absorption bands with their maximum peaks at 380 nm and 540 nm. The findings demonstrate that the optical properties of viologens can be tuned by the applied electrode potentials.

This study has come up with a method to treat a large amount of rice straw as agricultural by-products, reduce environmental pollution caused by burning straws, create new materials, which are of great significance in environmental protection, and increase the value of agricultural by-products. Along with the research and application of materials, the process of recovering and recycling used plastic packaging creates a new type of biodegradable nylon material and provides poly ethylene raw materials for production. The nano xenlulozo material was characterized by Fourier-transform infrared spectroscopy (FT-IR), and high resolution – transmission electron microscopy (HR-TEM).