A supramolecular solvent made up of nano-sized inverted hexagonal aggregates of 1-octanol is proposed for the microextraction of diphenylamine and its mono-nitrated derivatives in unburned single-base propellants. The procedure included the extraction of sub-gram quantities (30 mg) of homogenized propellant with 1.5 mL of the supramolecular solvent. Several conditions affecting extraction efficiency, for example the concentrations of the major components of the supramolecular solvent (tetrahydrofuran and alkanol), alkanol type, solvent pH, and extraction time, were investigated and optimized. The main forces for the microextraction of analytes in the nanostructured supramolecular solvent include both dispersion and hydrogen bond interactions. This mixed-mode mechanism resulted in high extraction efficiencies reaching low method detection limits (0.005-0.012 mg/g) without the need for extract evaporation. Under the optimum conditions, recoveries in samples ranged between about 82.6 and 98.7%. Compared to the reference method, the proposed method is simple and rapid, delivering accurate and precise results, and can be applied for routine determination of diphenylamine and its derivatives in propellants. The precision of the method, expressed as relative standard deviation, was about 4.3-10.9%.
Keywords: Propellants; Stabilizers; Supramolecular solvents.
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