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Abstract
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The nickel–aluminum layered double hydroxide (Ni–Al LDH) was synthesized by a simple coprecipitation
method and used as a solid-phase extraction (SPE) sorbent for separation and
pre-concentration of trace levels of salicylic acid (SA) from aqueous solutions. Extraction of analyte is
based on the adsorption of salicylate ions on the Ni–Al (NO3 −) LDH and/or their exchanging with LDH
interlayer NO3 − ions. The retained analyte on the LDH was stripped by 3 mol L−1 NaOH solution and its
concentration was subsequently determined spectrofluorometrically at em = 400nm with excitation at
ex = 270 nm. Various parameters affecting the extraction efficiency of SA on the Ni–Al (NO3
LDH, such as pH, amount of nano-sorbent, sample loading flow rate, elution conditions, sample volume and matrix
effects were investigated. In the optimum experimental conditions, the limit of detection (3 s) and enrichment
factor were 0.12gL−1 and 40, respectively. The relative standard deviation (RSD) for six replicate
determinations of 10gL−1 SA was 2.3%. The calibration graph using the pre-concentration system was
linear in the range of 0.3–45gL−1 with a correlation coefficient of 0.9985. The optimized method was
successfully applied to the determination of SA in blood serum, willow leaf and aspirin tablet.
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