1227络合比色法测定工业循环水中聚天冬氨酸

The determination for the concentration of polyaspartic acid in circulating water system by the colorimetry of complex and 1227

聚天冬氨酸与十二烷基二甲基苄基氯化铵(1227)络合形成离子缔合物,在0~40 mg/L浓度范围内,聚天冬氨酸的浓度与离子缔合物溶液的吸光度值呈线性关系:A=0.019 3+0.013 2C(mg/L),R2=0.993 7,检出限为0.09 mg/L,RSD为3.8%。研究了1227的加入量、稳定时间、p H等对吸光度的影响。结果表明,最佳条件为在波长420 nm处,1227加入量300 mg/L,p H 8以及稳定时间30 min时,测定体系的线性较好。利用吸光度值的变化求得两组分的吉布斯自由能ΔG=-16.5 k J/mol、结合常数K=767。此研究可用来测定循环水中聚天冬氨酸的含量,测定结果准确可靠。

The colorimetry method is established to determine the concentration of polyaspartic acid in circulating water,which based on the formation of complex between polyaspartic acid and dodecyl dimethyl benzyl ammonium chloride（ 1227） being measured via spectrophotometer in visible light region. The linear range of polyaspartic acid was from 0 to 40 mg/L,the linear equation was A = 0. 019 3 ＋ 0. 013 2 C（ mg/L） with correlation coefficient 0. 993 7,the detection limit was 0. 09 mg/L,RSD was 3. 8%. Factors that effect the extent of reaction,such as the dosage of 1227,p H value and stabilization time were studied to obtain the optimal experimental conditions. At the same time influences coming from the existence of other substances were also discussed as well as the elimination of their effects. Moreover,the binding constant（ K = 767） and gibbs free energy（ ΔG =-16. 5 k J/mol） of 1227 and polyaspartic acid were measured. This method has been successfully applied to determine polyaspartic acid in water systems with satisfactory results.