A new method for the determination of the nitrogen content of nitrocellulose based on the molar ratio of nitrite-to-nitrate ions released after alkaline hydrolysis

Elodie Alinat (1, 2, 3, 4) , Nathalie Delaunay (2, 3, 1) , Xavier Archer (4) , Jean-Maurice Mallet (2, 3) , Pierre Gareil (2, 3)

1 PECSA - Physicochimie des Electrolytes, Colloïdes et Sciences Analytiques
2 UPMC - Université Pierre et Marie Curie - Paris 6
3 PSL - Université Paris Sciences et Lettres
4 LCPP - Central laboratory of police prefecture

A new method was proposed to determine the nitrogen content of nitrocelluloses (NCs). It is based on the finding of a linear relationship between the nitrogen content and the molar ratio of nitrite-to-nitrate ions released after alkaline hydrolysis. Capillary electrophoresis was used to monitor the concentration of nitrite and nitrate ions. The influences of hydrolysis time and molar mass of NC on the molar ratio of nitrite-to-nitrate ions were investigated, and new insights into the understanding of the alkaline denitration mechanism of NCs, underlying this analytical strategy is provided. The method was then tested successfully with various explosive and non-explosive NC-containing samples such as various daily products and smokeless gunpowders. Inherently to its principle exploiting a concentration ratio, this method shows very good repeatability in the determination of nitrogen content in real samples with relative standard deviation (n = 3) inferior to 1.5%, and also provides very significant advantages with respect to sample extraction, analysis time (1 h for alkaline hydrolysis, 3 min for electrophoretic separation), which was about 5 times shorter than for the classical Devarda's method, currently used in industry, and safety conditions (no need for preliminary drying NC samples, mild hydrolysis conditions with 1 M sodium hydroxide for 1 h at 60 °C).

Mots clés: Smokeless gunpowder; Nitrogen content; Alkaline hydrolysis; Nitrocellulose

Domaines: Matériaux

Elodie Alinat, Nathalie Delaunay, Xavier Archer, Jean-Maurice Mallet, Pierre Gareil. A new method for the determination of the nitrogen content of nitrocellulose based on the molar ratio of nitrite-to-nitrate ions released after alkaline hydrolysis. Journal of Hazardous Materials, 2015, 286, pp.92-99. ⟨10.1016/j.jhazmat.2014.12.032⟩. ⟨hal-01110232⟩