酚试剂分光光度法测定饮用水中甲醛的改进

Improving Phenol Reagent Spectrophotometry for Determination of Formaldehyde in Drinking Water

目的：通过对试验条件的研究与改进,提高方法灵敏度,确保测定饮用水中甲醛的酚试剂分光光度法更加完善和稳定。方法：利用甲醛与酚试剂反应生成嗪,嗪在酸性溶液中被高铁离子氧化生成蓝绿色化合物,颜色深浅与甲醛含量成正比[1],据此可测定饮用水中甲醛含量。文章对入射波长、显色剂酸度、显色剂浓度、显色剂用量、酚试剂用量、加酚试剂后静置时间、显色温度和显色时间等影响因素进行了全面研究;并对改进后方法的灵敏度、精密度、准确度和检出限进行了探讨。结果：方法经改进后,甲醛浓度在0~0.20 mg/L范围内与吸光度呈良好线性关系,相关系数为0.9997,灵敏度为0.96 A/（mg/L）,检出限为3×10-3 mg/L,RSD为1.0%~2.3%,加标回收率为97%~102%。结论：该法经过改进,用于测定饮用水中甲醛含量更加稳定,提高了方法灵敏度,检出限更低,精密度和准确度更好;优于原法和国标方法,是一个简便、快速、准确、可行的测定饮用水中甲醛含量的方法。

Objective： Through the study of experimental condition and improvement, and improve the method of sensitivity, ensure that the determination of formaldehyde in the drinking water of phenol reagent spectrophotometry is more perfect and stable. Methods： using formaldehyde and phenol reagent reaction, lamictal in acid solution by high iron oxide generated blue-green compounds; color depth is proportional to the content of formaldehyde in, on the basis of determination of formaldehyde content in drinking water. In the paper, the incident wavelength, acidity of chromogenic agent, chromogenic agent concentration, dosage of chromogenic agent, the dosage of phenol reagent, the incubation time after phenol reagent, color temperature and color rendering time and so on influence factors in the comprehensive study; And the sensitivity of the improved method, precision, accuracy and detection limit are discussed in the paper. Results： the method after improvement, the formaldehyde concentration in 0~0.20 mg/L range and had good linear relationship between absorbance, the correlation coefficient is 0.9997, the sensitivity is 0.96 A/（mg/L）, the detection limit is 3 x 10.3 mg/L, RSD is 1.0 %-2.3 %, standard addition recovery is 97 %-102 %.Conclusion： the method is improved for the determination of formaldehyde content in drinking water is more stable, the method to improve the sensitivity and lower detection limit, precision and accuracy is better; it is better than the original method and gb method, it is a simple, rapid, accurate and feasible method of determination of formaldehyde content in drinking water.