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 ‐NO 2 to ‐NH 2 , 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 H 3 PO 4 and 3 M in HClO 4 . 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 ‐NH 2 to NH 3 in a Kjeldahl‐type apparatus. The sample does not require an acid digestion step. The ‐ NH 2 groups are readily converted to NH 3 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%.