Ion Chromatographic Determination of Iodide in Urine and Serum Using a Tubular Ion-Selective Electrode Based on a Homogeneous Crystalline Membrane

摘要

The use of a laboratory-made iodide ion-selective electrode with tubular configuration and based on a crystalline membrane (AgI/Ag2S) as the detector for ion chromatographic determination of iodide in urine and serum is described. A C18 reversed-phase column was coated with JV-cetylpyridinium chloride to prepare a low-exchange-capacity analytical column and with hexadecyltrimethylammonium bromide to prepare a concentrator pre-column. A 2.0 ml mkr1 flow rate of deionized water and 0.1 mol I-1 KNO3 solution was used for the pre-concentration and for the chromatographic separation, respectively. For optimum performance of the detector a background level of iodide was added into the column effluent. A linear relationship (r = 0.9997) between tubular electrode potential (as peak height) and iodide concentration in the range 5-400 ug I-1 and a detection limit of 1,47 |_Lg 1-1 were obtained. The method shows good reproducibility for both peak height (2.2% RSD) and retention time (1.3% RSD). Recoveries on its application to the samples were 93.0-100.9% for urine and 91.4-106.0% for serum.