title: On-line lab-in-syringe cloud point extraction for the spectrophotometric determination of antimony.
abstract: Most of the procedures for antimony determination require time-consuming sample preparation (e.g. liquid-liquid extraction with organic solvents), which are harmful to the environment. Because of the high antimony toxicity, a rapid, sensitive and greener procedure for its determination becomes necessary. The goal of this work was to develop an analytical procedure exploiting for the first time the cloud point extraction on a lab-in-syringe flow system aiming at the spectrophotometric determination of antimony. The procedure was based on formation of an ion-pair between the antimony-iodide complex and H(+) followed by extraction with Triton X-114. The factorial design showed that the concentrations of ascorbic acid, H2SO4 and Triton X-114, as well as second and third order interactions were significant at the 95% confidence level. A Box-Behnken design was applied to obtain the response surfaces and to identify the critical values. System is robust at the 95% confidence level. A linear response was observed from 5 to 50 µg L(-1), described by the equation A=0.137+0.050C(Sb) (r=0.998). The detection limit (99.7% confidence level), the coefficient of variation (n=5; 15 µg L(-1)) and the sampling rate was estimated at 1.8 µg L(-1), 1.6% and 16 h(-1), respectively. The procedure allows quantification of antimony in the concentrations established by environmental legislation (6 µg L(-1)) and it was successfully applied to the determination of antimony in freshwater samples and antileishmanial drugs, yielding results in agreement with those obtained by HGFAAS at the 95% confidence level.
authors.affiliation: Centro de Energia Nuclear na Agricultura, Universidade de São Paulo, P.O. Box 96, 13400-970 Piracicaba, SP, Brazil.
authors.forename: Rejane M
authors.initials: RM
authors.lastname: Frizzarin
authors.affiliation: Laboratory of Environmental Analytical Chemistry, University of the Balearic Islands, Carretera de Valldemosa km 7.5, 07122 Palma de Mallorca, Spain.
authors.forename: Lindomar A
authors.initials: LA
authors.lastname: Portugal
authors.affiliation: Laboratory of Environmental Analytical Chemistry, University of the Balearic Islands, Carretera de Valldemosa km 7.5, 07122 Palma de Mallorca, Spain.
authors.forename: José M
authors.initials: JM
authors.lastname: Estela
authors.affiliation: Centro de Energia Nuclear na Agricultura, Universidade de São Paulo, P.O. Box 96, 13400-970 Piracicaba, SP, Brazil.
authors.forename: Fábio R P
authors.initials: FR
authors.lastname: Rocha
authors.affiliation: Laboratory of Environmental Analytical Chemistry, University of the Balearic Islands, Carretera de Valldemosa km 7.5, 07122 Palma de Mallorca, Spain. Electronic address: victor.cerda@uib.es.
authors.forename: Victor
authors.initials: V
authors.lastname: Cerdà
keywords: Antileishmanial drugs; Antimony; Cloud point extraction; Lab-in-syringe; Waters