Azo dye degradation and metabolite formation were followedalong selected SBR cycles by HPLC with spectrophotometric detection at 220 nm using a LiChroCART Purospher STAR RP-18e column (250 mm × 4 mm). The eluent consisted of phosphate buffer (25 mM, pH 5.5) and acetonitrile. A gradient elution (0–50%acetonitrile for 30 min) was used with a flow of 0.7 mL min−1.2.3