极谱法测定牛奶中的三聚氰胺  

Detection of Melamine in Milk by Polarography

作　　者：吉喆[1] 陈文[1] 王铒[1] 杨捷 

机构地区：[1]成都理工大学材料与化学化工学院,成都610059

出　　处：《理化检验（化学分册）》2017年第9期1014-1019,共6页Physical Testing and Chemical Analysis(Part B:Chemical Analysis)

摘　　要：基于荧光素在pH 6.5的B-R缓冲溶液中可产生一灵敏的还原峰,而三聚氰胺的加入可降低其峰电流值,且降低值与三聚氰胺加入量呈显著相关性,采用极谱法测定牛奶中的三聚氰胺。依次将pH 6.5的0.2mol·L^(-1) B-R缓冲溶液7.5mL、1.0×10^(-4) mol·L^(-1)荧光素标准溶液2.5mL、三聚氰胺的标准溶液或适量样品溶液加入25mL比色管中,用水稀释至刻度,混匀后于45℃加热15min,采用极谱法测定体系还原峰电流的降低值。三聚氰胺的浓度在1.0×10^(-7)~1.0×10^(-5) mol·L^(-1)内与峰电流降低值呈线性关系,检出限(3s/k)为5.1×10^(-8) mol·L^(-1)。加标回收率为91.2%~99.1%,测定值的相对标准偏差(n=10)小于1.0%。用线性扫描极谱法研究了体系的电化学行为,证明了此极谱波为不可逆还原吸附波,电极反应物为荧光素。In a B-R buffer solution of pH 6.5,a sensitive polarographic reduction peak given by fluorescence（FRS）was observed,and the reduction peak current was lowered upon addition of melamine（MLM）.It was shown that significant correlationship was held between amount of co-existing melamine and the decrease of reduction peak current.Based on these facts,apolarographic method applied for determination of MLM in milk was proposed.0.2mol·L^-1 B-R buffer solution （pH 6.5,7.5mL）,1.0×10^-4 mol·L^-1 FRS solution （2.5mL） and definite amount of MLM standard solution or appropirate amount of sample solution were added successively to a 25 mL colorimetric tube and the mixed solution was diluted to mark with water.After thorough mixing,the solution was heated for 15 min at 45 ℃.The decrease of reduction peak current of the reaction system comparing with blank solution was measured by polarography.Linear relationship between values of decrease in peak current and mass concentration of MLM was obtained in the range of 1.0×10^-7-1.0×10^-5 mol·L^-1,with detection limit （3s/k） of 5.1×10^-8 mol·L^-1.Values of recovery were in the range of 91.2%-99.1%.Values of RSDs （n=10） were less than 1.0%.As shown by the results of linear sweeping polarography,the polarographic wave given by FRS at the electrode is irreversible reductive adsorptive wave and the electroactive compound is RFS.

关 键 词：极谱法 三聚氰胺 荧光素 牛奶 

分 类 号：O657.14[理学—分析化学]