示波伏安法测定碘酸钾碘盐中碘
OSCILLO-VOLTAMMETRIC DETERMINATION OF IODINE IN TABLE SALT SPIKED WITH POTASSIUM IODATE
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摘要: 在0.2 mol·L-1 NaOH底液中,碘酸钾在示波图阴极支-0.6 V和-1.6 V(vs.SCE)处产生两个切口.其中-1.6 V处切口较为灵敏、稳定,根据这些示波特性,建立了测定碘酸钾碘盐中碘含量的二次微分简易示波伏安法.其二次微分简易示波伏安峰峰高随碘酸钾浓度增大在一定范围内线性增长,线性范围为3.5×10-6-6.4×10-5mol·L-1,回归方程为h(V)= 141.40+1.03×106 c(mol·L-1 ),相关系数为0.999 1,检出限为1.0×10-6mol·L-1.对5.0×10-6mol·L-1碘酸钾5次测定的RSD为2.2%,回收率为100.3%.方法仪器简单、快速、无需通氮除氧.Abstract: In a medium of 0.2 mol·L-1 NaOH solution,two incisions at -0.6 V and -1.6 V(vs.SCE) a simple,on the cathodic branch of oscillopolarogram due to the presence of iodate were observed.Based on this fact,a simple second derivative oscillo-voltammetric method was established for the determination of iodine in table salt spiked with potassium iodate.It was shown by experimental results that the peak height of the incision at -1.6 V was linearly increased with iodate concentrations in range of 3.5×10-6-6.4×10-5mol·L-1.The regression equation was h(V)=141.40+1.03×106 c(mol·L-1),with a correlation coefficient of 0.999 1.Detection limit was 1.0×10-6mol·L-1.RSD (n=5) was 2.2% at the level of 5.0×10-6mol·L-1 of KIO3.This method has the characteristic of needing no complex instrument,ease in operation and unnecessary of removal of oxygen by blowing with nitrogen.