Flame Atomic Absorption Spectrometric Determination of Ultra Traces of Thallium(I) ion after Solid Phase Extraction by Octadecyl Silica Membrane Disk Modified by a New Schiff Base

摘要

A simple and reliable method has been developed to selectively separate and concentrate trace amounts of thallium ion from real samples for the subsequent measurement by flame atomic absorption spectrometry (FAAS).Thallium ions are absorbed quantitatively during passage of aqueous real samples through an octadecyl bonded silica membrane disk modified by 4-(4-Chloro-phenylazo)-2-[(4-hydroxy-phenylamino)-methylj-phenol.The retained Tl+ ions are then stripped from the disk quantitatively with a minimal amount of thiosulfate solution as eluent.The proposed method permitted large enrichment factors of about 130 and higher.The relative standard deviation for ten replicate extraction of thallium from 1 L samples containing 5 ug thallium is 1.2%.The break through volume for 5 mug thallium is 1000 mL.The limit of detection of the proposed method is 11.2 ng of Tl+ per 1000 mL.The effects of various cationic interferences on the recovery of thallium in binary mixtures were studied.The method was applied to the recovery of Tl~+ ions from natural water and human hair samples.