title: Highly selective ionic liquid-based microextraction method for sensitive trace cobalt determination in environmental and biological samples.
abstract: A simple and rapid dispersive liquid-liquid microextraction procedure based on an ionic liquid (IL-DLLME) was developed for selective determination of cobalt (Co) with electrothermal atomic absorption spectrometry (ETAAS) detection. Cobalt was initially complexed with 1-nitroso-2-naphtol (1N2N) reagent at pH 4.0. The IL-DLLME procedure was then performed by using a few microliters of the room temperature ionic liquid (RTIL) 1-hexyl-3-methylimidazolium hexafluorophosphate [C(6)mim][PF(6)] as extractant while methanol was the dispersant solvent. After microextraction procedure, the Co-enriched RTIL phase was solubilized in methanol and directly injected into the graphite furnace. The effect of several variables on Co-1N2N complex formation, extraction with the dispersed RTIL phase, and analyte detection with ETAAS, was carefully studied in this work. An enrichment factor of 120 was obtained with only 6 mL of sample solution and under optimal experimental conditions. The resultant limit of detection (LOD) was 3.8 ng L(-1), while the relative standard deviation (RSD) was 3.4% (at 1 microg L(-1) Co level and n=10), calculated from the peak height of absorbance signals. The accuracy of the proposed methodology was tested by analysis of a certified reference material. The method was successfully applied for the determination of Co in environmental and biological samples.
authors.affiliation: Analytical Chemistry Research and Development Group (QUIANID), (LISAMEN-CCT-CONICET-Mendoza), Av. Ruiz Leal S/N Parque General San Martín, M 5502 IRA Mendoza, Argentina.
authors.forename: Paula
authors.initials: P
authors.lastname: Berton
authors.forename: Rodolfo G
authors.initials: RG
authors.lastname: Wuilloud
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003035:Cobalt / Q000032:analysis* / Q000302:isolation & purification; D005618:Fresh Water / Q000737:chemistry; D052578:Ionic Liquids / Q000737:chemistry*; D057230:Limit of Detection; D000432:Methanol / Q000737:chemistry; D010573:Pesticide Residues / Q000032:analysis; D010936:Plant Extracts / Q000737:chemistry; D012015:Reference Standards; D012997:Solvents / Q000737:chemistry; D013054:Spectrophotometry, Atomic; D014131:Trace Elements / Q000032:analysis*
chemical_list: D052578:Ionic Liquids; D010573:Pesticide Residues; D010936:Plant Extracts; D012997:Solvents; D014131:Trace Elements; D003035:Cobalt; D000432:Methanol