P 1871 (OTTO) Picrylsulphonic acid solution, 5% (w/v) in H2O Cas no 2508-19-2 - used as a detonator for certain other explosive compounds. P 1871 (OTTO) Picrylsulphonic acid solution, 5% (w/v) in H2O Cas no 2508-19-2 - suitable for determination of primary amines.