2.4. Chemical analysis
To record chromatographic and spectrophotometric readings and to determine Panobinostat degree of OXA removal, the formation of oxidants and antimicrobial activity, samples were taken from the reactor at times 0, 1, 2, 3, 4, 5, 10, 15, 30, 45 and 60 min. 3 mL of sample were taken for readings of COD and TOC, at times 0, 60, 120, 240, 360 and 480 min. 300 mL of sample were required for BOD5 with sampling time at 0 and 480 min of reaction, which were obtained by performing the experiment several times to generate a composed sample. Sodium bisulfite was used to inactivate the oxidative species generated and then to stop the reaction.
OXA degradation was monitored under isocratic conditions using a Waters liquid chromatograph equipped with a 486 absorbance (UV–vis) detector set at 225 nm, and a LiChrospher® RP18 (250 × 4.6 mm ID) HPLC column. Optimum separation occurred using a mixture of phosphate buffer: Acetonitrile: Methanol (64:27:9 v/v) in isocratic mode, operating at a flow-rate of 0.6 mL min−1.