Fluorimetric determination of cerium with paracetamol

A simple, sensitive and selective method for determination of cerium(IV), based on the oxidative reaction between cerium(IV) and paracetamol, has been developed. The fluorescent species is an oxidation product of paracetamol and has excitation and emission maxima at 265 and 360 nm, respectively. The fluorescent intensity of the system is linear over the range 2.0 x 10(-7)-8.0 x 10(-6)M Ce(IV). The method has been applied in the determination of Ce(IV) in synthetic mixtures and ores with good accuracy being achieved.     

Fluorimetric determination of lithium with dibenzothiazolylmethane

Lithium is determined by measuring the fluorescence produced on reaction with dibenzothiazolylmethane; zinc is the only other metal that fluoresces. The practical limits for the determination of lithium in salts are from 0.5 to 20 μg although 0.01 μg can be determined in pure solutions.     

Fluorimetric determination of zinc with dibenzothiazolyl-methane

Dibenzothiazolylmethane produces a specific fluorescence with zinc in ethanolwater solutions. Zinc is determined quantitatively in solutions containing 0.05 to 50 mg of zinc/l. One part of zinc can be detected in the presence of 20,000 parts of cadmium and quantitative determinations of zinc in cadmium salts are readily done. The method can be applied to the analysis of non-ferrous alloys such as Dowmetals.     

Fluorimetric determination of zirconium with morin

Zirconium can be determination fluorimctrically with morin in 2M hydrochloric acid in the presence of such elements as Al, Be, Ga, Sb, Sn, Th and U, which fluorcsce much less strongly under the conditions, by measuring the fluorescence intensity before and after adding ethylenediaminetetraacetic acid. This substance destroys the fluorescence of zirconium only and the difference in fluorescence intensities corresponds to the concentration of zirconium in solution. The determination of zirconium in the presence of aluminum has especially been studied. Satisfactory accuracy can be obtained even when Al/Zr = 10,000, if the proper morin concentration is used. Iron docs not interfere if reduced to the ferrous state with mercap oacetic acid, Zirconium can be determined in silicate rocks without any separations except those made automatically in tlie sodium carbonate decomposition. Niobium and tantalum should not exceed 0.05%.     

酪氨酸作试剂荧光光度法测定亚硝酸根

亚硝酸盐广泛存在于土壤、食品及天然水中 ,是水体中氮循环的重要中间物。亚硝酸盐可引起急性中毒 ,还可以与仲胺和酰胺等结合成致癌的亚硝胺化合物 ,是造成环境污染的主要原因之一。因此 ,亚硝酸盐的含量是环境监测和食品分析的重要指标。荧光法测定亚硝酸根常用的试剂是 2 ,3 二氨基萘[1] ,但需用有机溶剂萃取 ,操作繁琐 ,而且由于试剂本身有毒 ,易造成二次污染。近年来有人报道了荧光猝灭法测定亚硝酸根[2 ,3] 。本文以亚硝酸根与酪氨酸反应产物在碱性介质中呈现强的荧光 ,其激发波长和发射波长分别为 31 8.0ｎｍ和 398.4ｎｍ ,建立了水…     

Fluorimetric determination of nitrite

A sensitive and rapid fluorimetric method for the determination of nitrite is described. The method is based on the reaction of nitrite with tryptophan to form a highly fluorescent compound in alkaline medium. The method has been applied in the determination of nitrite in water and food samples.     

Fluorimetric determination of ascorbic acid with o-phenylenediamine

A simple and sensitive fluorimetric method for the determination of ascorbic acid (AA) is described. The method is based on the condensation reaction between AA and o-phenylenediamine (OPDA) in the absence of the oxidant. The fluorescence intensity is measured at excitation and emission wavelengths of 360 and 430 nm, respectively. Under optimum condition, a linear relationship is obtained between the fluorescence intensity and the concentration of AA in the range of 0.05-40 μg ml⁻¹. The detection limit is 0.006 μg ml⁻¹, which is obviously lower than that of other fluorimetric methods reported.     

Fluorimetric determination of lactate with immobilized lactate dehydrogenase

In measuring inter-phase distribution coefficients (k_{$\text{1}\text{11}$})it is often convenient, and sometimes necessary, to obtain all of the analytical data from one phase. A rigorous formula, applicable to both low and high k_{$\text{1}\text{11}$} values has been derived; measurements of the distribution of mercury, methylmercury and ⁶⁷Cu²⁺ between various pairs of phases with this formula gave k_{$\text{1}\text{11}$} values similar to those obtained from other approaches.     

Fluorimetric determination of beryllium with pyridoxal-5-phosphate

A simple, rapid and selective method for the determination of beryllium with pyridoxal-5-phosphate has been developed. The system is only fluorescent (lambda(ex) 360, lambda(em) 460 nm) in the presence of a nitrogenous base such as ammonia, ethylenediamine or pyridine, owing to the possible formation of a ternary complex. The calibration graph is linear over the range 8-60 ng ml . The high selectivity of the method permits the determination of beryllium in various types of alloys.     

The determination of reducing carbohydrates using a cation-exchange column and potentiometric detection with a metallic copper electrode

Summary A metallic copper electrode is employed as a potentiometric detector for reducing carbohydrates after their separation on a cation-exchange column. A post-column reactant solution comprising 1 mM copper (II) and 35 mM ammonia is mixed with the column effluent and the metallic copper electrode provides a steady baseline potential by responding in a Nernstian manner to the level of copper ions present. This in turn is affected by the presence of eluted reducing carbohydrates, leading to an indirect detection method for these species. The method is applied to the detection of maltose, lactose, xylose, glucose, sorbose, fructose and arabinose. The electrode response mechanism is discussed and detection limits in the low nanomole range are reported. The potentiometric detector is shown to be more sensitive than refractive index detection.     

Fluorimetric determination of nucleic acids with terbium and lutetium

In this paper, fluorescence-enhancement of Tb-nucleic acids [fish sperm DNA (fsDNA) and yeast RNA (yRNA)] by Lu³⁺ is studied in detail and is applied to determine nucleic acids. The experiments indicated that under the optimum conditions, a linear relationship was obtained between the fluorescence intensity (I_f) and the concentration of nucleic acids. The linear range is 1.2×10⁻⁸-1.0×10⁻⁴ g/ml for DNA and 3.0×10⁻⁸-8.0×10⁻⁴ g/ml for RNA. The detection limits (signal/noise=3) for DNA and RNA were 4.8×10⁻⁹ and 7.0×10⁻⁹ g/ml, respectively. The mechanism of the co-luminescence effect is also discussed.     

Fluorimetric determination of oleandomycins with nicotinamide and 3-acetylpyridine

The method is based on a fluorescence reaction of the epoxy group with nicotinamide and 3-acetylpyridine. Oleandomycin phosphate and triacetyloleandomycin can be determined in the ranges 1–80 μg ml^?1and 5–80 μg ml^?1, respectively, with relative standard deviations of 3–5%. The method can be applied to pharmaceutical preparations. Results obtained by this method and by bioassay in an examination of residual potency agreed well when degradation was done under neutral or alkaline conditions.     

Fluorimetric determination of boron with resacetophenone as a reagent

Summary A method has been developed for the fluorimetric determination of boric acid, which gives a blue fluorescence with resacetophenone in sulphuric acid or phosphoric acid medium. The method has the advantage that the reaction does not require much time, because the fluorescence intensity reaches its maximum immediately after mixing the reagents and does not also decrease with time. The intensity of fluorescence can be measured with a fluorimeter and the amount of boric acid determined from a calibration curve.     

Fluorimetric determination of aluminium in serum

A convenient fluorimetric method for the routine determination of aluminium in serum has been developed using lumogallion [4-chloro-3-(2,4-dihydroxyphenylazo)-2-hydroxybenzene-1-sulphonic acid]. Losses of aluminium during deproteinisation of the serum were prevented by treatment with a combination of 20 or 30% m/V trichloroacetic acid (TCA) and 5% m/VTCA. Iron(III) was removed by extraction into chloroform with capriquat (methyltrioctylammonium chloride) as an Fe3+-lumogallion-capriquat ternary complex. The interference from Cu2+ was eliminated by using thiosulphate as a masking agent. The detection limit was 3.6 ng ml-1 and the calibration graph was linear up to 1.4 micrograms ml-1 of aluminium. Using the proposed method, the average concentration of aluminium in the serum of healthy subjects was found to be 6.8 ng ml-1, in agreement with values reported in the literature.     

Fluorimetric determination of tetracycline and anhydrotetracycline

Summary A rapid fluorimetric method employing the complexes of Al³⁺ with tetracycline (TC) and anhydrotetracycline (ATC) has been used for the measurement of the concentrations of TC and ATC in about 10^–7–10^–6 mol/l. The assay offers simplicity and rapidly compared with other methods. The recoveries in the determination of synthetic samples are in the range of 95–103% for TC and 101–120% for ATC. Several determinations of TC and ATC in serum and urine have been carried out with satisfactory results.     

Fluorimetric determination of zinc with pyrocatechin-1-aldehyde 2-benzothiazolylhydrazone

A rapid procedure for the spectrofluorimetric determination of 0.25 to 7.5 μg of zinc with PABTH, in a 50% ($\text{v}\text{v}$) DMSO-water medium at apparent pH 7.5 of Tris-HClO₄ is described (λ_ex = 425 nm, λ_ex = 490 nm, corrected). Interferences have been evaluated and the procedure applied to the determination of zinc in zinc-containing alloys.     

Fluorimetric determination of aromatic aldehydes with 4,5-dimethoxy-1,2-diaminobenzene

A sensitive fluorimetric method for the determination of aromatic aldehydes is described based on their reaction in dilute acid with 4,5-dimethoxy-1,2-diaminobenzene to give a compound which fluoresces intensely in alkaline solution. The fluorescence is stabilized by β-mercaptoethanol. The method is simple, selective for aromatic and arylaliphatic aldehydes, and sensitive; almost all the aldehydes can be determined at concentrations of 10^-8–10^-7 M.