Precise assay of TATB by the determination of total amino and nitro functional groups

Methods have been developed for the precise assay of the explosive l,3,5-triamino-2,4,6-trinitrobenzene (TATB) using procedures that quantitatively measure total nitro and/or total amino functional groups. The method for the determination of total nitro groups is based on the dissolution of TATB in DMSO-NaOH, electrolytic reduction of -NO2 to -NH2, and measurement by controlled-potential coulometry. The reduction is carried out at a mercury pool electrode at −0.60 V versus standard calomel electrode (SCE) in a supporting electrolyte 1 M in H3PO4 and 3 M in HClO4. Background corrections are low, and samples containing 0.1 mg to 2 mg of TATB per ml can be analyzed with a precision and accuracy of 0.25% to 0.5%. The method for determining total amino groups is based on the conversion of -NH2 to NH3 in a Kjeldahl-type apparatus. The sample does not require an acid digestion step. The - NH2 groups are readily converted to NH3 and distilled from a solution of NaOH and dimethylsulfoxide (DMSO). Individual samples of 120 mg-170 mg of TATB can be conveniently assayed for amino groups with an accuracy and precision of about 0.25%.