Figure 5:Typical chromatogram of standard mixture of sulfaquinoxaline sodium (1), vitamin K3 (2) and amprolium hydrochloride (3); Column, a ZIC-HILIC column (25.0 cm long 4.6 mm i.d.) with particle size of 5 m protected with a ZIC-HILIC guard column (20 mm 2.1 mm, 5 m); Mobile phase consisting of ACN and 0.2M NH4AC solution (85:15; v/v) at pH 5.7; flow rate 0.5 ml/min; ? at 263 nm; column temperature of 25C; Autosampler temperature of 15C. Peak 4 is due to sulfaquinoxaline impurity A.