Fluorimetric determination of ultratraces of lead by ion-pair extraction with cryptand 2.2.1 and eosin.
A spectrofluorimetric study of the extraction of lead into 1,2-dichloroethane, as an ion-pair formed between the cryptand 2.2.1-lead complex and the eosinate counter-ion is described. Optimum conditions for the extraction have been established and a new spectrofluorimetric determination of ultratraces of lead is proposed (detection limit 0.8 ng/ml; relative standard deviation 2.4% at the 60 ng/ml level). The metal:ligand:counter-ion molecular ratio in the extracted mononuclear ion-pair is 1:1:1. The equilibrium constants involved in the extraction have been estimated and refined by the Letagrop-DISTR program.
Gomis
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Departamento de Química Física y Analítica, Facultad de Química, Universidad de Oviedo, Oviedo, Spain.
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Lobo
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Medel
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