酚试剂法测定室内空气中甲醛的实验条件优化

为了提高酚试剂法测定室内空气中甲醛的准确性,优化实验条件,系统研究了盐酸介质浓度、显色剂加入量、显色时间、显色反应温度和稀释液类型等因素对吸光度的影响,研究结果表明,采用0.1 mol/L盐酸配制的硫酸铁铵显色剂,显色剂加入量对吸光度影响不显著,最佳加入量为0.4 mL;显色反应温度对吸光度影响明显,最佳温度应控制在25～35℃范围内;稳定的显色反应时间应控制在18～30 min内,以20 min为宜;当甲醛质量浓度较高时,可选用去离子水或酚试剂吸收液进行适当的稀释。在较优的实验条件下,测定的甲醛质量浓度与吸光度在0～2.0μg/mL范围内呈良好的线性关系,r=0.999 9。

Study on optimal experimental conditions of phenol reagent method for determining formaldehyde in indoor air

For improving the accuracy of the phenol reagent spectrophotometric determining formaldehyde in indoor air and obtaining the optimal experimental conditions, in this paper the effects of the concentration of hydrochloric acid, the color reagent usage, color reaction time, temperature on the absorhance and the diluent were studied. The results show that the new color reagent, ammonium ferric sulfate solution, is prepared by 0.1 mol/L hydrochloric acid; the effect of clout reagent usage on the absorbance is not significant, and the best addition is O. 4 mL; the effects of temperature on the absorbance is significant, and the best color reaction temperature should be controlled at within 25-5℃; the stable color reaction time should be controlled at within 18-30 min, and 20 min is most appropriate. When the concentration of formaldehyde in air is relatively high, phenol reagent or deionized water should be selected to dilute the absorption solution to appropriate volume. Under the optimal experimental conditions, the concentrtion of formaldehy is linear with the absorbance over the range from 0 to 2.0 μg/mL,r=0. 999 9.