Determination of phenols in natural and waste waters by capillary electrophoresis after preconcentration on magnetic nanoparticles coated with aminated hypercrosslinked polystyrene

An efficient sorbent for magnetic solid‐phase extraction was developed from Fe 3 O 4 nanoparticles covered with aminated hypercrosslinked polystyrene. The sorbent has a saturation magnetization of 47 emu/g and a surface area of 509 mg/g and was tested for the extraction of 11 phenols from aqueous media. The optimum conditions were as follows: pH 3; adsorbent mass, 20.0 mg; adsorption time, 30 min; eluent (acetone) volume, 0.5 mL; and desorption time, 5 min. The enrichment factor after desorption reached 1595‐1716 and the maximum adsorption capacity was 501‐909 mg/g. Capillary electrophoresis was applied successively to separate 11 phenols after solid‐phase extraction. The best separation was achieved using a fused silica capillary and borate buffer (pH 10.7) as a supporting electrolyte. After optimization, the linearity range was from 0.2 to 950 μg/L, and the limits of detection were 0.05‐0.2 μg/L. The relative standard deviation varied from 6.1 to 8.7% ( C  = 1 μg/L) and from 2.9 to 3.5% ( C  = 500 μg/L). The determination of phenols is complicated in eutrophic water and spring water with a high content of humic and fulvic acids.