Abstract
Carbamazepine (CBZ) is one of the most widely used antiepileptic drugs in Malaysia, so, it was detected in wastewater frequently. The electrochemical treatment process has been applied for the degradation of CBZ using graphite-PVC as an anode. However, two main by-products, namely, 10,11-dihydro10-hydroxy carbamazepine (HDX-CBZ) and 10,11-epoxycarbamazepine (EPX-CBZ) have been analysed and quantified using liquid chromatography-time of flight/mass spectrometry (LC-TOF/MS). HDX-CBZ and EPX-CBZ were analysed in positive ionisation mode and were separated chromatographically using 5 mm, 2 mm´150 mm C18 column at a flow rate of 0.3 mL/min. To improve sensitivity and detectability, SPE was applied as a pre-concentration step for the treated carbamazepine samples to extract and pre-concentrate HDX-CBZ and EPX-CBZ. However, three different solvents, namely, methyl tertiary butyl ether, acetone and methanol, have been optimized to enhance the recovery. The recovery was 85% and 92% for HDX-CBZ and EPX-CBZ, respectively, in the presence of methanol. The limit of quantification (LOQ) was 0.588 and 0.109 µg/L for both by-products, respectively. The concentration of HDX-CBZ and EPX-CBZ was 343 and 144 μg/L, respectively, after 20 min of treatment, then, it was decreased to 17.2 and 9.8 μg/L at 40 min. Finally, both by-products were eliminated after 60 min.
Elucidation and Characterization of New Chlorinated By-Products after Electrochemical Degradation of Hydrochlorothiazide Using Graphite–Poly Vinyl Chloride Electrode