Layered double hydroxides: a novel nano-sorbent for solid-phase extraction

The nickel–aluminum layered double hydroxide (Ni–Al LDH) was synthesized by a simple co-precipitation method with controlled pH and followed by hydrothermal treatment. The obtained nano-structured inorganic material was employed, for the first time, as a new solid-phase extraction (SPE) sorbent for the extraction and pre-concentration of trace levels of fluoride ions from aqueous solutions. An indirect method was used for monitoring of extracted fluoride ions. The method is based on the quenching effect of extracted fluoride ions upon the fluorescence intensity of Al–oxine complex via the forming of AlF₆³⁻, which was determined spectrofluorometrically at λ_em = 510 nm with excitation at λ_ex = 404 nm. The effect of several parameters such as type of interlayer anion in Ni–Al LDH structure, pH, sample flow rate, elution conditions, amount of nano-sorbent, sample volume and co-existing ions on the extraction efficiency of the analyte were investigated. The results showed that fluoride ions could be retained on the Ni–Al (NO₃⁻) LDH at pH 6.0 and stripped by 1.2 mL of 3.0 mol L⁻¹ NaOH. In the optimum experimental conditions, the limit of detection (3 s) and enrichment factor were 9.0 ng mL⁻¹ and 50, respectively. The optimized method was successfully applied to the determination of fluoride concentration in various water samples. The results obtained from the proposed method were successfully compared with those provided by standard SPADNS method.     

稀土混合共发光效应的研究——(铽-钆-钇)-铕-噻吩甲酰三氟丙酮-氯化甲基三烷基铵-Triton X-100荧光体系

本文研究了铽(Tb)、钇(Y)、钆(Gd)及它们的混合物对铕(Eu)-噻吩甲酰三氟丙酮(TTA)-氯化甲基三烷基铵(N_(263))-Triton X-100体系的共发光效应,发现稀土离子混合物的共发光效应具有线性加和性,用混合共发光体系不仅能保持单个稀土离子的共发光体系的增敏性,而且抗干扰能力增强,并经过实际样品分析的验证,结果令人满意。     

Fluorescence spectroscopy applied to the optimisation of a desalting step by electrodialysis for the characterisation of marine organic matter

The isolation and characterisation of marine dissolved organic matter (DOM) are still not readily achieved today. The study of this chemically complex material is particularly difficult, especially as it is hindered by the high salinity of seawater. It is therefore essential to develop a method in which a sufficient quantity of marine organic matter can be collected for structural analyses. Reverse osmosis (RO) is often used for the concentration of DOM from freshwaters, due to the fact that DOM is not modified during RO and that DOC recoveries are high (about 80%). Unfortunately, RO cannot be used directly to isolate marine DOM, since both salts and organic matter are concentrated during the process. Therefore, marine samples have to be desalted before their concentration by RO.     

烟酸诺氟沙星和乳酸诺氟沙星的荧光特性及应用

研究了烟酸诺氟沙星和乳酸诺氟沙星在不同介质中的荧光特性。采用荧光分光光度法测定了烟酸诺氟沙星和乳酸诺氟沙星的含量。烟酸诺氟沙星和乳酸诺氟沙星分别在0.025—2.5μg/mL和0.01—2μg/mL范围内,其荧光强度与浓度线性关系良好。     

鬼臼毒素及其衍生物的光谱研究

本文对鬼臼毒素及其衍生物的吸收光谱进行了详细研究，分别运用了紫外法，荧光法，脉冲辐解法，激光光解法。对一些瞬态中间体进行理论和实验的推测，从而对鬼臼素及其衍生物的抗肿瘤活性和毒性的研究提供了有力证据，为进一步合成具有高抗肿瘤活性，低毒性的新物质指明了方向和提供了理论基础。     

Fluorescence Quenching Method for the Assay of Three Cephalosporins Using the Combined Trigonometric Function of Fuorier Series

Three cephalosporins (CS), namely, Cefadroxil, Cephalexin and Cephradine were assayed in their pharmaceutical preparations through the utility of mercurochrome fluorescence quenching phenomenon proceeding the alkaline degradation of cephalosporins. The decrease in mercurochrome fluorescence intensity was directly proportional to the degraded cephalosporins (DCS) in concentration range of 0.01–0.05 mg%. The parameters for the applications of the combined trigonometric function of Fourier series (Δt method) were investigated aiming a t cancelling the systematic error appsared during the use of the differential spectrofluorometric method (ΔF-method). The results of Δt′ method was statistically compared with those of the orthogonal function method (ΔP, method). Both methods were found of equal potential in correcting for the interferences. The Stern-Volmer equation was here derived. using ΔF. Δt′ and ΔP2 i n order to assess the quenching power of DCS t o mercurochrome compared with CS. The quenching constant ratios of DCS to CS were extremely high and decreasing in the order of cefadroxil, cephradine and ephalexin.     

香草醛缩氨基硫脲-铅高灵敏荧光反应的研究及其应用

合成了新荧光试剂香草醛缩氨基硫脲 ,并研究了此试剂与铅荧光反应的最佳条件。在λex em=368 45 0nm处 ,测定铅的线性范围为 3.0～ 45 .0 μg L ,检测限为 0 .72 μg L ,该方法已用于猪肝粉和小麦粉中痕量铅的测定。     

Kinetic Spectrofluorometric Determination of Thioctic Acid in Bulk and Pharmaceutical Preparations via its Oxidation with Cerium(IV)

A highly simple and sensitive kinetic spectrofluorometric method was developed for the determination of thioctic acid. The method is based on the oxidation of the studied drug with cerium(IV) ammonium sulfate in acidic medium. The fluorescence of the produced Ce(III) was measured at 365 nm after excitation at 255 nm. The different experimental parameters affecting the development and stability of the reaction product were carefully studied and optimized. The method is applicable over the concentration range of 0.02 to 0.12 μg/mL with a detection limit of 6.06 × 10^?3 μg/mL and a quantification limit of 0.02 μg/mL. The method was successfully applied for the assay of the studied drug in pharmaceutical formulations. The results obtained were in good agreement with those obtained with the reference method.     

一种新型炭化装置的研制及其在单质硒检测中的应用

本文研制了一套新型装置,该装置可用于单质硒与其他氧化态硒的分离。整套装置采用硼硅酸盐玻璃材质,由玻璃杯底座和上盖腔体两部分组成,上盖腔体顶部连接空气冷凝管。当炭化温度设为300℃,时间设为30min时,玻璃杯底座样品中的单质硒挥发并在空气冷凝管内壁冷凝,用Na2S溶液收集后经氧化还原反应得到具有荧光的硒衍生物,采用荧光光谱法定量检测硒衍生物。方法测定单质硒的线性范围为0.0~1.6μg,相关系数R2=1.0000。5份硒粉的回收率实验表明:平均回收率为97.77%~103.34%,相对标准偏差为0.95%。将上述装置应用于Z0206细菌发酵的富硒多糖样品单质硒的检测,5份样品分析结果表明,单质硒的平均含量为1923.23μg/g。     

Investigation on the supramolecular recognition behaviour of sulfonatocalix[6]arene with amino benzoic acid isomers

The formation of the complexation behaviour of host molecules water-soluble p-sulfonatocalix[6]arene (C6AS) with amino benzoic acid (ABA) isomers including o-amino benzoic acid (OABA), m-amino benzoic acid (MABA), and p-amino benzoic acid (PABA) – three guest molecules – has been studied by fluorescence spectrophotometric and nuclear magnetic resonance (NMR) spectroscopy. Experimental conditions including the concentration of C6AS and medium acidity were investigated in detail. The results showed that C6AS forms 1:1 complexes with amino benzoic isomers in water. Their stability constants determined by steady-state fluorescence measurement showed that C6AS has stronger recognition with PABA than with OABA or MABA. Moreover, their stability constants of C6AS complexing with three kinds of guest molecules were the largest at pH = 4.0, indicating C6AS has the strongest recognition ability with the dipolar ion of amino benzoic isomers. In addition, to obtain information about the binding model of the interaction, ¹HNMR studies were carried out. The related mechanism is proposed to explain the complexation processes.