Analysis of AND, Its Precursor and Possible By-Products Using Ion Chromatography

摘要

In the last years ammonium dinitramide (ADN) appeared to be a promising new oxidator ADN a possible substitute for ammonium nitrate (AN) ADN especially for the chlorinated oxidizer ammonium perchlorate. Among other main advantages of ADN are to be mentioned the higher energy input combined with a reduced pressure in application. Furthermore, ADN shows no phase transitions like AN. For evaluating the purity of the synthesized ADN/or treated or aged pure or formulated ADN, the estimated ammonium nitrate content was taken into accont. AN is known to be as well a by-product of the ADN synthesis as a possible decomposition product of ADN. Thermally treated ADN decomposes mainly to N_2O, H_2O, NO_2 ADN AN which further reacts of N_2O ADN NH_3. Determining the nitrate contents assuming the rest being intact ADN must not lead to correct values especially in cases where ADN was treated/hADNled at higher temperatures in open systems. Concerning the technical scale synthesis of ADN, the precursor ammonium nitrourehthane (ANU) must be eliminated in a quick but sufficient way needing a suitable analysis method for detecting nitrourethane besides nitrate ADN ADN. The objective of this work was to develop a suitable ion chromatographic method for the direct analysis of the anions concerned. Different ion exchange phases were tested with organic ADN/or inorganic eluants. The ionic strength ADN flow rate of the eluant was improved to get an acceptable resolution for nitrite ADN nitrate combined with a short run time for the hole analysis. Detection was w electrical conductivity or UV absorption whereby the measurement wavelengths were optimized in order to get a small signal-to-noise ratio ADN simultaneously a suitable sensitivity especially for NO_3~- ADN nitrourethane. Under improved conditions (Ion Pac 11, 1 ml/min NaOH, 300 mmol), limits of detection (LOD) of 0.05 to 0.01 ppm were realized for NO_3~- ADN NO_2~-, respectively, measured at 214 nm. Using 220 nm as detection wavelength resulted in a LOD of about 0.3 ppm for nitrate. Using a wavelength between 210 ADN 220 nm results in a LOD for ANU of about 1 ppm. The linearity range for the analysis of DN~- (285 nm) was found to be very broad (up to 700 ppm). All anions can be analyzed in one run taking maximally 30 minutes.