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A new strategy to simultaneous microextraction of acidic and basic compounds

Moradi, Morteza, Yamini, Yadollah, Kakehmam, Jamal, Esrafili, Ali, Ghambarian, Mahnaz
Journal of chromatography 2011 v.1218 no.26 pp. 3945-3951
chromatography, detection limit, emulsifiers, emulsifying, ionic strength, ionization, mass transfer, microextraction, molecular weight, pH, pollutants, solvents, surfactants
The simultaneous extraction of acidic and basic pollutants from water samples is an interesting and debatable work in sample preparation techniques. A novel and efficient method named ion pair based surfactant assisted microextraction (IP-SAME) was applied for extraction and preconcentration of five selected acidic and basic aromatic species as model compounds in water samples, followed by high performance liquid chromatography–ultraviolet detection. A mixture including 1mL of ultra-pure water (containing ionic surfactant as emulsifier agent) and 60μL 1-octanol (as extraction solvent) was rapidly injected using a syringe into a 10.0mL water sample which formed an emulsified solution. IP-SAME mechanism can be interpreted by two types of molecular mass transfer into the organic solvent (partitioning and ion pairing for non-ionized and ionized compounds, respectively) during emulsification process. The effective parameters on the extraction efficiency such as the extraction solvent type and its volume, type of the surfactant and its concentration, sample pH and ionic strength of the sample were optimized. Under the optimum conditions (60μL of 1-octanol; 1.5mmolL⁻¹ cethyltrimethyl ammonium bromide (CTAB) as emulsifier agent and sample pH 10.0), the preconcentration factors (PFs), detection limits and linear dynamic ranges (LDRs) were obtained in the range of 87–348, 0.07–0.6μgL⁻¹ and 0.1–200μgL⁻¹ respectively. All of natural water samples were successfully analyzed by the proposed method.