Mixed Micelle-mediated Extraction and Preconcentration for Spectrophotometric Determination of Trace Amounts of 1,1-Dimethylhydrazine in Water and Soil Samples

A new micelle-mediated phase separation method using mixed micelles of anionic surfactant sodium dodecyl sulfate and non-ionic surfactant Triton X-114 has been developed for preconcentration of ultratrace amounts of 1,1-dimethylhydrazine (UDMH) as a prior step to its spectrophotometric determination. The method was based on extraction of dimethylhydrazone - the coloured product of reaction of UDMH with p-nitrobenzaldehyde in the presence of electrolyte as phase separation inducing agent. Dimethylhydrazone concentrated in a surfactant-rich phase was then determined spectrophotometrically at 404 nm. Optimal extraction and reaction conditions (e.g. surfactant and reagent concentrations, temperature) were studied and analytical characteristics of the method (e.g. limit of detection, linear range, preconcentration and enhancement factors) were determined. Linearity was observed in the range 10-500 ng mL(-1) UDMH and detection limit of the method was 5.0 ng mL(-1). Interfering effects from some cations, anions, and organic compounds were also investigated. The proposed method was successfully applied to the determination of UDMH in water and soil samples.