Silica gel-immobilized-vanillin derivatives as selective solid-phase extractants for determination of chromium (III) in environmental samples by ICP-OES

A method is described for the selective extraction of chromium(III) from aqueous solutions and natural water samples, based on the use of two newly synthesized solid-phase extractors via silica gel-immobilized-vanillin derivatives (I,II). Experimental conditions for effective adsorption of trace levels of Cr(III) were optimized with respect to different experimental parameters using batch and column procedures in detail. The optimum pH values for the separation of Cr(III) simultaneously on the newly sorbents were both 4.0 and complete elution of Cr(III) from the sorbents surface was carried out using 2.0 mL of 0.5 mol L^− 1 HCl. The sorption capacity of phase I towards Cr(III) was found to be 0.700 mmol g^− 1 where the sorption capacity of phase II was 0.538 mmol g^− 1. The detection limits (3σ) of the method defined by IUPAC were found to be 0.87 and 0.64 ng mL^− 1 with enrichment factors of 100 and 75 for phases I and II, respectively. The method has been applied for the determination of Cr(III) in biological materials and water samples with satisfactory results.     

种子溶胀悬浮聚合法制备香草醛分子印迹聚合物微球

以分散聚合法制备的聚苯乙烯微球为种子,采用单步溶胀悬浮聚合法,香草醛为模板分子,甲基丙烯酸为功能单体,乙二醇二甲基丙烯酸酯为交联剂,在水相中成功制备了分子印迹聚合物微球,通过扫描电镜、静态吸附和高效液相色谱手段对其进行表征。结果表明,该微球对香草醛具有较高的吸附能力和良好的特异选择性,用于液相色谱固定相可将其与结构类似物阿魏酸快速基线分离。     

Combination of computational methods,adsorption isotherms and selectivity tests for the conception of a mixed non-covalent–semi-covalent molecularly imprinted polymer of vanillin

A novel molecularly imprinted polymer (MIP) for vanillin was prepared by photo initiated polymerization in dichloromethane using a mixed semi-covalent and non-covalent imprinting strategy. Taking polymerisable syringaldehyde as “dummy” template, acrylamide was chosen as functional monomer on B3LYP/6-31+G(d,p) density functional theory computational method basis with counterpoise. The binding parameters for the recognition of vanillin on imprinted polymers were studied with three different isotherm models (Langmuir, bi-Langmuir and Langmuir–Freundlich) and compared. The results indicate an heterogeneity of binding sites. It was found and proved by DFT calculations that the specific binding of vanillin in the cavities is due to non-covalent interactions of the template with the hydroxyphenyl- and the amide-moieties. The binding geometry of vanillin in the MIP cavity was also modelled. The obtained MIP is highly specific for vanillin (with an imprinting factor of 7.4) and was successfully applied to the extraction of vanillin from vanilla pods, red wine spike with vanillin, natural and artificial vanilla sugar with a recovery of 80%.     

Vanillin-coumarin hybrid molecule as an efficient fluorescent probe for trace level determination of Hg(II) and its application in cell imaging

An efficient Hg²⁺ selective fluorescent probe (vanillin azo coumarin, VAC) was synthesized by blending vanillin with coumarin. VAC and its Hg²⁺ complex were well characterized by different spectroscopic techniques like ¹H NMR, QTOF-MS ES⁺, FTIR and elemental analysis as well. VAC could detect up to 1.25 μM Hg²⁺ in aqueous methanol solution through fluorescence enhancement. The method was linear up to 16 μM of Hg²⁺. Negative interferences from Cu²⁺, Ni²⁺, Fe³⁺, and Zn²⁺ were eliminated using EDTA as a masking agent. VAC showed a strong binding to Hg²⁺ ion as evident from its binding constant value (2.2 × 10⁵), estimated using Benesi-Hildebrand equation. Mercuration assisted restricted rotation of the vanillin moiety and inhibited photoinduced electron transfer from the O, N-donor sites to the coumarin unit are responsible for the enhancement of fluorescence upon mercuration of VAC. VAC was used for imaging the accumulation of Hg²⁺ ions in Candida albicans cells.     

多元校正-光度法同时测定食品中的香兰素和乙基麦芽酚

香兰素、乙基麦芽酚在紫外区均有吸收,其吸收光谱严重重叠。在pH=2．87的B-R缓冲溶液中对香兰素和乙基麦芽酚两组分混合溶液进行光度测定,所得重叠光谱数据分别用经典最小二乘法(CLS)、偏最小二乘法(PLS)、主成分回归法(PCR)处理,并用于食品样品的测定,获得了较好的定量分析结果。香兰素和乙基麦芽酚的线性范围均为1．0～20．0mg／L;检出限分别为0．478mg／L和0．559mg／L。     

Bioconversion of vanillin to vanillyl alcohol in a two-phase reactor

One of the next challenges in the use of biocatalysts (enzyme or microbial cells) is the upgrading of biological reactions of oxidoreduction. The oxidoreductases need cofactors that must be regenerated. Practical experience shows that this is most readily achieved by using living cells of microorganisms. Living cells ofSaccharomyces cerevisiae are able to bioconvert vanillin to vanillyl alcohol (1). By working with a two-phase reactor (dodecanol—feeding medium) it has been possible to use higher vanillin concentrations without inhibiting the bioconversion (2).     

Preparation and characterization of vanillin thiosemicarbazone complexes with Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II)

Complexes of vanillin thiosemicarbazone (3-methoxy-4-hydroxybenzaldehyde thiosemicarbazone), (vtsch) with several divalent metal ions have been isolated. Structures have been assigned to these complexes based on electrical conductivity, magnetic susceptibility and spectroscopic measurements     

A highly uniform CuO@SiO2 porous sphere with improved electrochemical sensing performance for the accurate determination of vanillin in food samples

A porous sphere of CuO@SiO₂ was obtained by simple calcination of the copper silicate (CuSiO₃) sphere. The formation of the porous sphere was studied in detail with the support of various physical characterization techniques. The CuO@SiO₂ was coated on an electrode surface where it demonstrates high catalytic activity for the electro-oxidation of vanillin in phosphate buffer solution (PBS; pH 7.0). The modified electrode has good surface adsorption (1.861 × 10^?10 mol cm^?2) and rate constant (2.866 × 10⁵ cm³ mol^?1 s^?1) characteristics for vanillin detection. The CuO@SiO₂-modified surface exhibited good linear range (0.05 μM–1.2 μM and 6.2 to 111.2 μM), detection limit (53 nM), sensitivity (2.88 μA μM^?1 cm^?2), selectivity, stability, and reproducibility. The CuO@SiO₂-modified electrode was further examined for the determination of vanillin in real samples including biscuits and chocolates with satisfactory recoveries.     

生物膜电极反应器降解对氨基二甲基苯胺的研究

采用生物膜电极法降解对氨基二甲基苯胺, 并与生物法降解和电化学降解的效果进行了比较.