Verapamil Impurity H;2-(3,4-dimethoxyphenyl)-5-[2-(3,4-dimethoxyphenyl)ethyl-methylamino]-2-ethylpentanenitrile;Benzeneacetonitrile, α-[3-[[2-(3,4-dimethoxyphenyl)ethyl]methylamino]propyl]-α-ethyl-3,4-dimethoxy-;Verapamil EP Impurity H HCl;Verapamil Impurity N12