DETERMINATION OF PRIMARY EXPLOSIVE AZIDES IN ENVIRONMENTAL-SAMPLES BYSEQUENTIAL INJECTION AMPEROMETRY

The application of flow injection methodology to the determination of trace concentrations of primary explosives is presented, The approach is demonstrated with a sequential injection amperometric method for th e determination of the azide ion (N-3(-)) The proposed method can be a pplied to the determination of sodium azide or lead azide, a primary e xplosive, without regard to other sources of lead in environmental sam ples, The sequential injection system used for the analysis forms the basis for a proposed field-portable instrument for the analysis of pri mary explosives, A microporous gas permeable membrane in a gas diffusi on unit (GDU) is used to separate the analyte from other anions that c an also be oxidized at the amperometric cell, The behaviour of the GDU was optimized with respect to the pH of the donor stream and the timi ng of the preconcentration step, A study of anions that are commonly f ound in environmental samples showed that the species that will interf ere with the analytical signal can be removed by the GDU, Results from three water samples that were spiked with 0.40 ppm of azide are prese nted, RSDs in the range 3-5% were typically obtained using the method, The useful working range of the method was linear up to 0.5 ppm and n on-linear up to 20 ppm (second-order model), The limit of detection wa s 24.6 ppb.