应用酸性铬蓝K的A_N=0双波长补偿系数光度法测定铜(Ⅱ)

Determination of Copper(Ⅱ) with Acid Chrome Blue K by A_N=0 Dual-wavelength Compensation Coefficient Spectrophotometry

在pH=12.7的NaOH介质中,铜（Ⅱ）与酸性铬蓝K（ACBK）形成深红色配合物,应用该配合物生色对试剂ACBK褪色产生100%相消干扰的波长533 nm作为负峰波长,建立了ACBK测定铜（Ⅱ）的AN=0双波长补偿系数光度法。该法能消除显色剂ACBK褪色对生成物Cu（ACBK）生色的相消干扰,测得生色法真实吸光度,消除生成物生色对有色剂ACBK褪色的相消干扰;测得褪色法近似真实吸光度,其灵敏度是上述两法之和。于波长λp573 nm,λN533 nm测得信号吸光度补偿系数fs为4.135,信号摩尔吸光系数为4.56×10^4L.mol^-1.cm^-1,是经典光度法的3.73倍。方法线性范围为0.02-1.60 mg.L^-1,配合物的摩尔比为Cu∶ACBK=1∶1。测定了某些水样中的铜（Ⅱ）,并对方法进行了检验,回收率为96%-104%。

An AN=0 dual-wavelength compensation coefficient spectrophotometric method has been established for the determination of copper（Ⅱ） using 533 nm as the discoloring peak s wavelength.The method was based on the red dark chelate formation between copper（Ⅱ） and acid chrome blue K（ACBK） in the NaOH medium（pH=12.7）.This method could determine the real absorbance of the chromogenic Cu（ACBK） through eliminating the destructive interference of discolored ACBK on Cu（ACBK） and could also determine the similar real absorbance of the ACBK through eliminating the destructive interference of Cu （ACBK） on the discoloration of ACBK. This method provided 2-fold increase in sensitivity compared with the conventional spectrophotometric methods. The compensation coefficient fs of absorbance signal is 4. 135 at wavelength of 1p 573 nm and ,λN 533 nm and the signal molar absorptivity is 4. 56×10^4 L · moL^-1·cm^-1 , which is 3. 73 times greater than that obtained by traditional method, and the linear range is 0.02-1.60 mg.L^-1 Cu（ II ）. The developed method has been applied for the determination of Cu（ II ） in water samples with recovery in the range of 96%-104%.