Ionic liquid based microextraction combined with derivatization for efficient enrichment/determination of asulam and sulfide

Abstract

This study reports 2 new simple derivatization-based dispersive liquid-liquid microextraction (DLLME) methods for spectrophotometric ultratrace determination of asulam and sulfide. 1-Naphthol (in the presence of nitrite) and N,N-diethyl-p-phenylenediamine (in the presence of Fe(III)) were used to derivatize asulam and sulfide, respectively. In the enrichment methods, the formed derivatives were preconcentrated into microdroplets of the in situ formed water insoluble ionic liquid (IL), 1-hexyl-3-methylimidazolium hexafluorophosphate. Monitoring was performed at 526 nm for asulam and at 664 nm for sulfide, after dissolution of the IL-rich phases into the basic ethanolic solution and ethanol for asulam and sulfide, respectively. Beer's law was obeyed in the ranges of 1.0-80.0 and 0.1-5.0 ng mL$^{-1}$ for asulam and sulfide, respectively. Limits of detection for asulam and sulfide determination by the DLLME methods were 0.18 and 0.019 ng mL$^{-1}$, respectively. Various foreign cations, anions, organics, and pesticides were tested to evaluate the selectivity of the DLLME methods. The methods were successfully applied to the determination of asulam and sulfide in various environmental, wastewater, and urine samples.