葡萄糖氧化酶催化荧光测定的非酶体系研究

多数氧化酶及其底物都是重要的临床检验指标[1]，目前普遍采用酶荧光法或酶显色法，通过氧化酶催化氧化底物生成H刃。，过氧化物酶（HRP）催化H刃2氧化生成荧光／生色底物，实现间接测定［’j．酶法测定的缺点是体系不稳定、反应条件苛刻、费用较高．最近Mitani等［’j报道了非酶法化学发光测定葡萄糖氧化酶，灵敏度高，但需要特殊试剂，且测定时间较长．我们用Fenton反应［‘j将H。O。转化为羟基自由基（“OH），进而氧化对苯二甲酸生成荧光物质，建立了荧光测定葡萄糖氧化酶的非酶法，详细研究了荧光指示剂的选择、Fenton试剂的改进…     

荧光法测定碱性磷酸酶及其标记物

本文研究了以４－甲基伞形酮磷酸酯（４－ＭＵＰ）为底物测定碱性磷酸酶（ＡＬＰ）活性的高灵敏荧光法及其应用于人血清ＩｇＧ的含量测定。通过纯化４－ＭＵＰ，优化分析条件，使方法的灵敏度有较大提高，实用性也得到改善，测定ＡＬＰ的线性范围为１．７×１０＾－５￣１．７×１０＾－８ＩＵ／ｍＬ，检出限为４．０×１０＾－９ＩＵ／ｍＬ，本法已成功地应用于血清样品ＡＬＰ的测定。作为一个例子，通过测定免疫标记物ＨｕＩｇＧ－     

Highly sensitive and selective optical chemosensor for determination of Cu2+ in aqueous solution

A highly selective and sensitive rhodamine-based colorimetric chemosensor (1) for quantification of divalent copper in aqueous solution has been investigated in this work. It was designed using salicylaldehyde hydrazone and rhodamine 6G as copper-chelating and signal-reporting groups, respectively. In environmentally friendly media (50% (v/v) water/ethanol and 10 mM NaAc–HAc neutral buffer (pH 7.0)), the sensor exhibited selective absorbance enhancement to Cu²⁺ over other metal ions at 529 nm, with a dynamic working range of 0.05–5.00 μM and a detection limit of 10 nM Cu²⁺, respectively. To achieve fluorometric determination of Cu²⁺, the Cu²⁺-induced absorbance enhancement of 1 was efficiently converted to fluorescence quenching by fluorescence inner filter effects using rhodamine B (RB) as a fluorophore. The selectivity and sensitivity of fluorescence analysis were similar to those of absorptiometric measurement. Both absorptiometric and fluorometric methods were successfully applied to the detection of Cu²⁺ in three water samples.     

Speciation of Cr(VI)/Cr(III) in environmental waters by fluorimetric method using central composite, full and fractional factorial design

In this approach a fluorometric technique has been developed to study chromium speciation, based on optimised conditions using chemometric methods of experimental design and central composite design. Full and fractional factorial design was used for evaluation of the effective factors in determination of Cr(VI) by fluorometric using Rhodamine-6G in the presence of H₂SO₄. Theory and methodology of a central composite design as a chemometric method for the optimisation of analytical procedures were developed in this approach. It was found that the analytical performance for measurement at the point of optimum in this technique is superior and more accurate than that of one variable at a time. Cr(VI) and Cr(III) were measured in a wastewater sample using the proposed technique. The results confirm the selective determination and speciation of Cr(VI)/Cr(III).     

Fluorometry of singlet oxygen generated via a photosensitized reaction using folic acid and methotrexate

A method for the fluorometry of singlet oxygen (¹O₂) using less fluorescent folic acid and its analogue, methotrexate (MTX), was examined. Folic acid and MTX were decomposed into a strongly fluorescent pteridine compound via a photosensitized reaction by ¹O₂-generating photosensitizers in a deuterium oxide solution. The fluorescence intensity increased in proportion to the irradiation time or the number of photons absorbed by the photosensitizer. This method using the fluorescence enhancement of these folic acid analogues can be applied to determine the quantum yield of ¹O₂ generated through a photosensitized reaction in deuterium oxide. The background fluorescence of MTX is quite smaller than that of folic acid, indicating that MTX can be used for the more sensitive detection of ¹O₂. Figure (DOC 37.0 KB)     

Fluorometric Characteristics of a Wave‐Guide Cell with Low Refractive Index

Recently, Teflon AF2400 (AF 1600, and AF 1601) was commercialized (DuPont Fluoroproducts, Wilmington, DE, U.S.A), that has a refractive index (1.29) lower than water (1.33), and which means that the wave‐guiding of light is possible in water. In this study, we used Teflon AF 2400 as a waveguide capillary longpath cell for fluorometry. He‐Cd and Ar⁺ lasers were used as the excitation source, at 325 nm and 514.5 nm respectively. The length of the capillary wave‐guide cell was 18.70 cm. The was wound twice on a flat surface (loop diameters: 2 cm and 3 cm). The excitation was executed through the wave‐guide cell and the fluorescence from the wound capillary cell wall was collected in a perpendicular direction to the loop. With excitation at 325 nm, the fluorescence intensity at 450 nm emitted from the cell wall decreased along with the increase in the refractive index of the solvent. This can be caused by attenuation of the source light due to absorption by the solvent. In our experiment, the solvent of higher refractive index has the higher absorption at 325 nm. On the other hand, the fluorescence intensity at 590 nm, with excitation at 514.5 nm, increases with increased refractive index of the solvent. This result shows that an increase in the refractive index of the solvent is preferable for maintaining the wave‐guiding of the source light. Here, the characteristics of fluorescence spectrometry are discussed in terms of the collection of fluorescence from the wave‐guide capillary cell wall.     

荧光法测定水样中的硒(Ⅳ)、硒(Ⅵ)和有机硒

本文提出了水样中硒（Ⅳ）、硒（Ⅵ）和有机硒的荧光测定方法。基于酸性介质中２,３－二氨基萘与硒（Ⅳ）的选择性反应,直接测定硒（Ⅳ）;利用盐酸还原硒（Ⅵ）和ＨＮＯ３－ＨＣｌＯ４消化有机硒后,用差减法分别测出硒（Ⅵ）和有机硒。检出限０．０７μｇ／Ｌ,线性范围０～１０μｇ／Ｌ。硒（Ⅳ）、硒（Ⅵ）和有机硒的相对标准偏差与回收率分别为２．４％和９８．５％～１０１．５％、３．１％和９４．８％～１０３％、４．０％和９４．５％～９８．８％。     

A Comparison of Fluorescent Pigments From Flavobacterium and Sphingobacterium Species

Abstract

An extraction procedure was developed for the isolation of fluorescent pigments from species of Flavobacterium and Sphingobacterium. This procedure was conducted at room temperature. Thereby the possibility of thermal degradation of the fluorescent pigments present in these organisms was reduced compared to previously reported extraction methods in which pigments were extracted after heating with strong base. Extracts from strains of eight species of these two genera have been evaluated using a video fluorometer (VF). This instrument rapidly provides a two-dimensional fluorescence spectrum of each extract. Data from replicate extracts of the organisms have been compared in order to evaluate the potential for identification of these microorganisms on the basis of their fluorescent pigment content. Similarities between the fluorescence spectra of two of the Flavobacterium species and Sphingobacterium mizutae support earlier studies which have shown that these organisms are related on the basis of their content of menaquinones and cellular fatty acids.