Trace analysis of mefenamic acid in human serum and pharmaceutical wastewater samples after pre-concentration with Ni–Al layered double hydroxide nano-particles

In this work, the nickel–aluminum layered double hydroxide (Ni–Al LDH) with nitrate interlayer anion was synthesized and used as a solid phase extraction sorbent for the selective separation and pre-concentration of mefenamic acid prior to quantification by UV detection at λ(max)=286 nm. Extraction procedure is based on the adsorption of mefenamate anions on the Ni–Al(NO(3)(−)) LDH and/or their exchange with LDH interlayer NO(3)(−) anions. The effects of several parameters such as cations and interlayer anions type in LDH structure, pH, sample flow rate, elution conditions, amount of nano-sorbent and co-existing ions on the extraction were investigated and optimized. Under the optimum conditions, the calibration graph was linear within the range of 2–1000 µg/L with a correlation coefficient of 0.9995. The limit of detection and relative standard deviation were 0.6 µg/L and 0.84% (30 µg/L, n=6), respectively. The presented method was successfully applied to determine of mefenamic acid in human serum and pharmaceutical wastewater samples.