On-line packed magnetic in-tube solid phase microextraction of acidic drugs such as naproxen and indomethacin by using Fe3O4@SiO2@layered double hydroxide nanoparticles with high anion exchange capacity.

The authors describe a 3-component nanoparticle system composed of a silica-coated magnetite (Fe3O4) core and a layered double (Cu-Cr) hydroxide nanoplatelet shell. The sorbent has a high anion exchange capacity for extraction anionic species. A simple online system, referred to as "on-line packed magnetic-in-tube solid phase microextraction" was designed. The nanoparticles were placed in a stainless steel cartridge via dry packing. The cartridge was then applied to the preconcentration acidic drugs including naproxen and indomethacin from urine and plasma. Extraction and desorption times, pH values of the sample solution and flow rates of sample solution and eluent were optimized. Analytes were then quantified by HPLC with UV detection. Under optimal conditions, the limits of detection range from 70 to 800 ng L-1, with linear responses from 0.1-500 μg L-1 (water samples), 0.6-500 μg L-1 (spiked urine), and 0.9-500 μg L-1 (spiked plasma). The inter- and intra-assay precisions (RSDs, for n = 5) are in the range of 2.2-5.4%, 2.8-4.9%, and 2.0-5.2% at concentration levels of 5, 25 and 50 μg L-1, respectively. The method was applied to the analysis of the drugs in spiked human urine and plasma, and good results were achieved. Graphical abstract Fe3O4@SiO2@CuCr-LDH magnetic nanoparticles were synthesized and packed in to a stainless steel column. The column was applied to solid phase microextraction of acidic drugs from biological samples.