Synthesis of cellulose nanofibers-based ImSalophen@Fe3O4 as a green sorbent for magnetic solid-phase extraction of chlorophenols followed by quantification via high-performance liquid chromatography-ultraviolet detection

Abstract

An effective, sensitive, relatively-fast and cost-effective method was developed to determine four types of selected chlorophenols (CPs) including 4-cholorophenol, 2,4-dicholorophenol, 2,5-dicholorophenol and 2,4,6-tricholorophenol in several kinds of honey, black tea and bovine milk samples through applying Cellulose Nano-Fiber (CNF)-ImSalophen@Fe3O4. CNF-ImSalophen@Fe3O4 has been synthesized using a very simple, easy, cost-effective, efficient and fast method. First, a magnetic CNF was used as the substrate. Next, imidazole was created on the surface of the magnetic CNF. Thereafter, the Cl-Salophen Schiff base was accommodated on the prepared magnetic CNF-Im. The prepared sorbent was used for the extraction of selected analytes. The extracted analytes were desorbed via organic solvent and analyzed through high-performance liquid chromatography-ultraviolet detection (HPLC-UV). The strong interactions between the sorbent and the selected analytes (intermolecular hydrogen bonding, and π-π interactions) made this sorbent capable of high extraction performance and capacity. Under the optimized condition, the method linearity was in the range of 0.2–500 µg/L for the selected analytes in water. The calibration curves showed a determination of coefficient higher than 0.9986. The limits of detection and limits of quantification were calculated to be between 0.05–0.14 µg/L and 0.16–0.46 µg/L, respectively. In order to calculate the method precision, the inter-day and intra-day relative standard deviations were determined to be between 3.2 and 4.7 % in three selected concentrations. Furthermore, the enrichment factors were found to be 36, 31, 33 and 37 for 4-cholorophenol, 2,4-dicholorophenol, 2,5-dicholorophenol and 2,4,6-tricholorophenol, respectively. Moreover, the calculated absolute recoveries were between 62 and 74 %. The proposed method was also employed for the analysis of various real samples such as honey, bovine milk and black tea. The obtained recoveries indicated that the method was useful and applicable in complicated real samples.