Spectrofluorometric Determination of Hydrogen Peroxide

A Spectrofluorometric method for microdetermination of H₂O₂ has been developed. The method is based on the oxidation of hydrogen peroxide with ceric ion in acid solution and measurement of the fluorescence during titration of the Ce(III) ions produced. The fluorescent species have excitation and emission maxima at 260 and 360 nm, respectively. The detection limit of measurement by this method was 0.1 ppm hydrogen peroxide.     

Spectrofluorometric method for determination of the total mercury content in environmental samples — Waste waters

A highly selective spectrofluorometric method for the determination of total mercury (Hg) in waste waters is described. Fluorescence quenching of rhodamine B with Hg(II) in the presence of iodide, after a concentration step, is the basis of this sensitive method. All forms of mercury, including organic compounds, are pre-oxidized to ionic mercury by acidic potassium permanganate. The final and complete oxidation is achieved by adding potassium persulphate and heating. Hg(II) was reduced by tin(II) chloride and Hg vapour driven by an air stream into an absorption solution containing potassium permanganate and sulphuric acid, using a closed, recirculating air stream. In this solution fluorescence quenching of rhodamine B at an excitation wavelength of 485 nm and emission wavelength of 586 nm was measured. The recoveries were done by adding 3.0 g Hg/100 ml to each sample before the digestion. It was indicated that the recoveries for determining mercury in waste waters were 98.3%–102.7%. The method gives reliable results down to a concentration of 10 ng Hg/ml waste water.     

1,3-环己二酮荧光法测定食品中的痕量甲醛

甲醛与1,3-环己二酮-组胺在弱酸性缓冲介质中反应生成强荧光化合物,由此建立一种测定食品中痕量甲醛的荧光分光光度法.在优化的实验条件下,反应体系的相对荧光强度与甲醛浓度呈良好的线性关系,该方法的线性范围为0.02～1.00μg/mL,检出限为1.8×10-3μg/mL,对0.75μg/mL甲醛平行测定11次,其相对标准偏差为2.0%.该方法用于食品中甲醛的测定,回收率为81.2%～87.5%,与乙酰丙酮法对照,结果基本一致.     

1,3-环己二酮荧光法测定食品中的痕量甲醛

甲醛与1,3-环己二酮-组胺在弱酸性缓冲介质中反应生成强荧光化合物,由此建立一种测定食品中痕量甲醛的荧光分光光度法.在优化的实验条件下,反应体系的相对荧光强度与甲醛浓度呈良好的线性关系,该方法的线性范围为0.02～1.00μg/mL,检出限为1.8×10-3μg/mL,对0.75μg/mL甲醛平行测定11次,其相对标准...