Ion pair-based dispersive liquid–liquid microextraction combined with UV-Vis spectrophotometry as a circuitous assay for nitrite
This paper proposes a fast and reliable dispersive liquid–liquid microextraction (DLLME) method for the determination of trace levels of nitrite by UV-Vis spectrophotometry. The method relies on the reaction of nitrite with excess iodide in an acidic medium to form triiodide, and then its extraction into CCl4 using trioctylmethylammonium chloride (Aliquat 336) as a dispersing agent. Some important parameters such as reaction conditions and the type and volume of extraction solvent and dispersant were investigated and optimized in detail. Under the optimum conditions, the calibration graph was linear over the range of 5.0 to 300.0 ng mL−1 with a limit of detection of 0.4 ng mL−1. The relative standard deviations (RSD) for ten replicate determinations of nitrite at concentrations of 20 and 75 ng mL−1 were calculated to be 1.6 and 0.7%, respectively. The developed method was validated via the Griess method and successfully applied to the determination of nitrite in water, vegetable and meat product samples.