18-Methyl Mestranol;Levonorgestrel EP impurity V;Levonorgestrel Impurity V (Aromatic Levonorgestrel);Levonorgestrel Impurity 22(Levonorgestrel EP Impurity V);Levonorgestrel EP Impurity V (Aromatic Levonorgestrel);13β-ethyl-3-methoxy-17α-ethynyl-gona-1,3,5(10)-trien-17β-ol;Levonorgestrel EP IMP V;Levonorgestrel EP impurity