2-ethylisonicotinonitrile;2-Ethyl-4-pyridinecarbonitrile;2-Ethylpyridine-4-carbonitrile;4-Cyano-2-ethylpyridine;4-Pyridinecarbonitrile, 2-ethyl-;Ethionamide EP Impurity D;2-ethylisonicotinonitrile ISO 9001:2015 REACH;Ethionamide Impurity 4 (Ethionamide EP Impurity D)