Synthesis and Application of the Magnetic Nanocomposite GO-Chm for the Extraction of Benzodiazepines from Surface Water Samples Prior to HPLC-PDA Analysis

Nowadays, the interest in preparing new, cheap and simple adsorbents that are used in sample preparation is on the rise. Graphene oxide (GO) nanomaterials and nanocomposites have become increasingly popular due to the novel methods of syntheses that have been published. Owing to their vast specific surface area and their π-delocalized electron system they possess, they are appropriate for the adsorption of a variety of aromatic organic compounds, being utilized either as adsorbents in analytical methods or as filter materials for the removal of pollutants in water. Pharmaceutical compounds, such as benzodiazepines, end up in surface waters caused by consumption or their disposal through sewage, thus becoming pollutants. In the present study, an analytical method has been developed and validated for the determination of two model-analytes of benzodiazepines by HPLC-DAD and their sample preparation protocol which consists of the Stir bar magnetic solid phase extraction (SB-MSPE) method, evaluating therefore the nanocomposite material as a decent adsorbent. The separation took place with the usage of an analytical column C18 RP-HPLC in 10 min. For the alprazolam (ALP) and the flunitrazepam (FLT), the LODs and LOQs were 3 ng/mL and 10 ng/mL, respectively, while the relative recoveries ranged between 93.6–112.9% and the RSDs were 1.11–9.50%. Finally, the material was examined for its reusability and was found that it can be used for over eight cycles of extraction/elution.