Multivariate optimisation of norfloxacin precocentration in surface water samples: A case of polysulfone-based polymer inclusion membranes (PIMs)

Norfloxacin belongs to a group of contaminants of emerging concern and its levels should be monitored in the environment. However, most conventional instruments struggle to detect trace levels of this contaminant in environmental samples. In this case, a polysulfone-based polymer inclusion membrane method was developed to enrich and separate norfloxacin in surface waters, followed by detection with HPLC UV–VIS. To achieve this, MODDE 13.1 software was used to optimise the variables crucial for the enrichment and separation of norfloxacin using a surface response methodology model with 30 experimental runs. The optimal operating conditions were predicted as pH 8.5, source solution concentration of 70 µg/L and receiver solution concentration of 0.7 M NaCl. The model predicted a maximum enrichment factor of 87.43. A test in the optimal operational conditions was conducted and the obtained experimental enrichment factor of ∼ 88.14 verified the reliability and validity of the proposed model. The limit of detection for the proposed method was found to be 8.71 µg/L. Lastly, application in surface waters indicated that polysulfone PIMs have the potential to enrich, separate and monitor fluoroquinolones antibiotics.