conjugated 17-oxosteroids are extracted with a sep-pak c18 cartridge , prelabelled with 2,4-dinitrophenylhydrazine in trichloroacetic acid-benzene solution and then separated by high-performance liquid chromatography on a reversed-phase c18 column using a mobile phase of 70 % methanol in a buffer consisting of 50 mm sodium acetate in 2 % ( v/v ) acetic acid .
C0142785
sodium acetate
C0000983
acetic acid