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Visual fluorimetry of trace lead using ion-pair extraction onto an octadecylsilanized silica disk

Japan Society for Analytical Chemistry
Publication Date
  • Lead
  • Visual Fluorimetry
  • Ion-Pair Extraction
  • Ods Disk
  • Dbc 2.2.2
  • Eosin Y
  • Physics


A rapid and simple method has been developed for the determination of trace lead ion using an octadecylsilanized (ODS) silica disk cartridge. The ion-pair of a lead complex with 5,6-14,15-dibenzo-4,7,13,16,21,24-hexaoxa-1.10-diazabicyclohexacosane (DBC 2.2.2) and tetrabromofluorescein (Eosin Y) was extracted from a sample solution onto an ODS filter at pH7.0. It was found that the addition of 20 wt% ethanol to the sample solution significantly enhanced the solid phase extraction. The lead concentration was determined by visual fluorimetry under ultraviolet light in the dark. The ion-pair has excitation and emission maxima at 530 nm and 560 nm in the solid phase, respectively. When measured with a densitometer, the linear range of this method is up to 2.9×10^-8 mol dm^-3(6 ppb). The detection limit is 5.0×10^-10 mol dm^-3 (100 ppt) by visual determination and 3.4×10^-9 mol dm^-3 (700 ppt) by densitometry. The relative standard deviation for 1.2×10^-3 mol dm^-3 (2.3 ppb) of lead is 5.6% (n=7). The method is essentially free from matrix interference. The proposed method can easily be performed and provides good precision and accuracy.

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