Doping-induced detection and determination of propellant grade hydrazines by a kinetic spectrophotometric method based on nano and conventional polyaniline using halide ion releasing additives

Abstract

A kinetic spectrophotometric method is described for the detection and determination of propellant grade hydrazines and its derivatives based on their reaction with 1-chloro-2,4-dinitrobenzene (CDNB) incorporated in a solution matrix of polyaniline-Emaraldine Base (Pani-EB) to produce HCl. This strong acid protonates (dopes) Pani (EB-Blue) to form Pani Emeraldine salt (ES-Green). A kinetic study based on the gradual decrease in absorbance at 626 nm for both nano and conventional Pani–CDNB systems was carried out at 50 °C and 60 °C under optimized conditions in the dynamic concentration range of 0.1–0.004 M. Initial rate and fixed time methods were adopted for constructing calibration curves. Hydrazines were determined based on the linear relationship between percent absorbance change at 30 min. and their concentration. R.S.D. for five replicate determinations of each one of these hydrazines using both systems is less than 1.5%. Minimum detectable limits for hydrazines were found for both systems. This method was successfully applied for determination of hydrazines in tap water with satisfactory analytical results.