Dispersive solid-phase extraction of selected nitrophenols from environmental water samples using a MOF-based nanosorbent

Metal-organic frameworks (MOFs) are a class of porous materials with great potentials in separation via extraction [1, 2]. Amongst the common extraction techniques, dispersive solid-phase extraction (d-SPE) as a rapid and simple technique has gained a great deal of interests in analysis of environmental samples [3, 4]. This study has centered on the establishment of an efficient and reliable analytical extraction method leading to an accurate trace determination of a class of compounds with high toxicity and extremely slow degradability, namely nitrophenols. In addition, an efficient extraction followed by determination of nitrophenols at trace level in environmental samples is of great importance for raising public health awareness and prevention of compounds-related human diseases. The above objectives was achieved via a four-stage route as follows: First, the synthesis a proper nano-adsorbent (UiO-66-NH2, metal–organic framework) through a number of chemical reactions. Second, the structure confirmation of the as-prepared sorbent using X-ray based analytical instruments was made. Third, the optimization of the dispersive solid phase extraction process for finding out the optimal extraction conditions was performed. Finally, the validation of the method of analysis followed by the implication of the method for analysis of the targets in real environmental samples including waste water, surface water was made. Under the optimal extraction conditions, the calibration curves for the analytes were linear over the concentration range of 1-250 ng/L. The accuracy of the method was tested by the relative recovery experiments on the fortified real samples with the results falling within the range of 90 to 116 %, while the corresponding precisions varied in the span of 3.9-12.5%. Based on a signal-to-noise ratio of 3 (S/N=3), the method detection limits were determined for the target analytes.