Application of zinc/aluminum layered double hydroxide nanosorbent in a fixed-bed column for SPE-preconcentration followed by HPLC determination of diclofenac in biological and hospital wastewater samples

Abstract

A zinc/aluminum layered double hydroxide (Zn/Al LDH) with carbonate interlayer anions was synthesized by the co-precipitation method. The prepared sorbent was examined for the solid phase extraction (SPE) and high performance liquid chromatography (HPLC) determination of the trace amounts of diclofenac (DCF) in human serum, as a complex matrix, and hospital wastewater samples. The first step of the procedure was the extraction of DCF by the synthesized Zn/Al LDH via an anion exchange mechanism, in which the interlayer carbonate anions were involved. A univariate sequential optimization procedure was conducted to find the optimal value of the parameters affecting the extraction process. The second step was the elution of the adsorbed DCF by a sodium hydroxide solution (2 mol L−1), followed by HPLC analysis of DCF. Under the optimal experimental conditions, the calibration plots for the determination of DCF in hospital wastewater and human serum samples were linear in the ranges of 3–415 (R2 = 0.999) and 9–300 (R2 = 0.997) μg L−1, respectively. The corresponding limits of detection were found to be as 0.16, 1.5 μg L−1, and the evaluated preconcentration factors were 41 and 37. The stability of the studied LDH allowed using a column packed with this adsorbent for 185 adsorption-desorption cycles. The results demonstrated the potentials of the developed method for efficient preconcentration and thus precise trace analysis of DCF in real samples.