Ionic liquid-based, single-drop microextraction for preconcentration of cobalt before its determination by electrothermal atomic absorption spectrometry.

An effective and environmentally friendly single-drop microextraction method was developed for the preconcentration of ultratraces of cobalt before its determination by electrothermal atomic absorption spectrometry (ETAAS). A microdrop of 1-hexyl-3-methylimidazolium hexafluorophosphate, [C6MIM][PF6], was used to extract Co(II) ions as an ammonium pyrroldinedithiocarbamate (APDC) complex. The sensitivity was improved by increasing the volume of the suspended drop. Several variables affecting microextraction efficiency and the ETAAS signal-such as pyrolysis and atomization temperature, pH, APDC concentration, extraction time, drop volume, and stirring rate-were investigated and optimized. Under the optimum experimental conditions, the detection limit (3 SD) was 0.04 microg/L, and the enrichment factor was 120. The RSD for five replicate determinations of Co(II) at 0.5 microg/L was 4.5%. The developed method was validated by analysis of a Standard Reference Material and applied to the determination of cobalt in water samples.

Hollow fiber based-liquid phase microextraction using ionic liquid solvent for preconcentration of lead and nickel from environmental and biological samples prior to determination by electrothermal atomic absorption spectrometry.

A simple and effective hollow fiber based-liquid phase microextraction (HF-LPME) technique by using ionic liquid, 1-hexyl-3-methylimidazolium hexafluorophosphate, [C(6)MIM][PF(6)], coupled with electrothermal atomic absorption spectrometry (ETAAS) was developed for the determination of lead and nickel in environmental and biological samples. Ammonium pyrroldinedithiocarbamate (APDC) was used as chelating agent. Several factors that influence the microextraction efficiency and ETAAS signal, such as pH, APDC concentration extraction time, amounts of ionic liquid, stirring rate, pyrolysis and atomization temperature were investigated and the microextraction conditions were established. In the optimum experimental conditions, the detection limits (3 s) of the method were 0.03 and 0.02 microg L(-1), for Ni and Pb, respectively and corresponding relative standard deviations (0.5 microg L(-1), n=6) were 4.2% and 5%. The developed method was validated by the analysis of certified reference materials and applied to the determination of lead and nickel in real samples.

Ultra-trace determination of lead in water and food samples by using ionic liquid-based single drop microextraction-electrothermal atomic absorption spectrometry.

An improved single drop microextraction procedure was developed for the preconcentration of lead prior to its determination by electrothermal atomic absorption spectrometry. Ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate [C4MIM][PF6], was used as an alternative to volatile organic solvents for extraction. Lead was complexed with ammonium pyrroldinedithiocarbamate (APDC) and extracted into a 7-microL ionic liquid drop. The extracted complex was directly injected into the graphite furnace. Several variables affecting microextraction efficiency and ETAAS signal, such as pyrolysis and atomization temperature, pH, APDC concentration, extraction time, drop volume and stirring rate were investigated and optimized. In the optimum experimental conditions, the limit of detection (3s) and the enhancement factor were 0.015 microg L(-1) and 76, respectively. The relative standard deviation (RSD) for five replicate determinations of 0.2 microg L(-1) Pb was 5.2%. The developed method was validated by the analysis of certified reference materials and applied successfully to the determination of lead in several real samples.

Ionic liquid-based single drop microextraction combined with electrothermal atomic absorption spectrometry for the determination of manganese in water samples.

Room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate [C(4)MIM][PF(6)], was used as an alternative to volatile organic solvents in single drop microextraction-electrothermal atomic absorption spectrometry (SDME-ETAAS). Manganese was extracted from aqueous solution into a drop of the ionic liquid after complextaion with 1-(2-thiazolylazo)-2-naphthol (TAN) and the drop was directly injected into the graphite furnace. Several variables affecting microextraction efficiency and ETAAS signal, such as pyrolysis and atomization temperature, pH, TAN concentration, extraction time, drop volume and stirring rate were investigated and optimized. In the optimum experimental conditions, the limit of detection (3s) and the enhancement factor were 0.024 microg L(-1) and 30.3, respectively. The relative standard deviation (RSD) for five replicate determinations of 0.5 microg L(-1) Mn(II) was 5.5%. The developed method was validated by the analysis of a certified reference material (NIST SRM 1643e) and applied successfully to the determination of manganese in several natural water samples.