论文部分内容阅读
1 引言铬是水源和其他环境的污染物之一,铬的分析越来越受到人们的重视。我们曾研究了铈(Ⅳ)-对乙酰氨基酚体系,发现铬(Ⅵ)对于对乙酰氨基酚的荧光有猝灭作用,本文在此基础上,提出了以荧光熄灭法进行铬的定量分析。当铬的浓度在1.25×10~(-6)～1.5×10~(-4)mol/L的范围内与荧光强度的下降成线性关系。本文还研究了干扰离子的影响,并用此方法测定了铸铁及工业废水中铬的含量。2 实验部分2.1 仪器与试剂 RF-540型荧光分光光度计(日本岛津)。铬标准贮存液,0.01mol/L;对乙酰氨基酚贮存液,0.01mol/L;硫酸溶液,4mol/L。2.2 实验方法 在10ml比色管中,依次加入适量的铬(Ⅵ)标准溶液(5×10~(-4)mol/L),0.4ml对乙酰氨基酚溶液(5×10~(-4)mol/L),硫酸溶液2ml,以蒸馏水定容至刻度,摇匀,水浴加热15min,然后冷却至室温。在λ_(ex)=350nm,λ_(em)=400nm的条件下,以试剂空白为参比,测定荧光强度的降低。3 结果与讨论3.1 对乙酰氨基酚浓度的影响 实验结果表明,加入5×10~(-4)mol/L对乙酰氨基酚溶液的量为0.3～0.6ml时,荧光熄灭显著,本实验采用加入量为0.4ml。3.2 硫酸浓度的影响 当4mol/L硫酸加入量为2ml时,体系的荧光强度降低最大。另外,沸水浴加热时间为15min时,荧光熄灭显著。3.3 工作曲线 铬(Ⅵ)的浓度在1.25×1
1 Introduction Chromium is one of the pollutants of water sources and other environments. The analysis of chromium has drawn more and more attention. We have studied the cerium (IV) - acetaminophen system and found that chromium (VI) quenches the fluorescence of paracetamol. On this basis, we propose a quantitative analysis of chromium by fluorescence quenching. When the concentration of chromium in the range of 1.25 × 10 ~ (-6) ~ 1.5 × 10 ~ (-4) mol / L decreases linearly with the fluorescence intensity. This paper also studied the influence of interference ions and used this method to determine the content of chromium in cast iron and industrial wastewater. 2 Experimental 2.1 Instruments and reagents RF-540 fluorescence spectrophotometer (Shimadzu). Chromium standard stock solution, 0.01mol / L; paracetamol stock solution, 0.01mol / L; sulfuric acid solution, 4mol / L. 2.2 Experimental Methods In a 10ml colorimetric tube, add appropriate amount of chromium (Ⅵ) standard solution (5 × 10 -4 mol / L), 0.4 ml paracetamol solution (5 × 10 -4) mol / L), sulfuric acid solution 2ml, dilute to volume with distilled water, shake, water bath heating 15min, then cooled to room temperature. Under the condition of λ_ (ex) = 350nm and λ_ (em) = 400nm, the decrease of fluorescence intensity was measured by using the reagent blank as a reference. 3 Results and discussion 3.1 The effect of acetaminophen concentration The experimental results showed that the fluorescence quenching was significant when the amount of acetaminophen solution was 5 × 10 -4 mol / L was 0.3-0.6 ml. In this experiment, The amount of 0.4ml. 3.2 The effect of sulfuric acid concentration When 4mol / L sulfuric acid added amount of 2ml, the fluorescence intensity of the system to reduce the maximum. In addition, boiling water bath heating time of 15min, the fluorescence quench significantly. 3.3 working curve chromium (Ⅵ) concentration of 1.25 × 1