DETERMINATION OF MALEIMIDES IN THE FORM OF ACID SALTS Russian patent published in 2000 - IPC

FIELD: analytical methods. SUBSTANCE: low-concentration maleimide solutions in concentrated acetic acid are successively treated first with nitration mixture (10% potassium nitrate solution in concentrated sulfuric acid) and then, 10-12 min later, with 20% aqueous alkali solution, after which optical density of solutions is measured at characteristic wavelength. Following maleimides have been investigated: N-o-tolyl-, N-p-tolyl-, and N-1-naphthylmaleimides. Threshold of detectability is 0.5-0.7 mcg/ml, determination reproducibility of the order of 6%, and determination accuracy no higher than 4%. Determination time is 15-20 min. EFFECT: increased sensitivity and accuracy, and decreased determination time. 5 tbl