Ferrite nanospheres-based magnetic solid-phase extraction for determination of domoic acid in seawater samples using high-performance liquid chromatography with tandem mass spectrometry
A simple, rapid and sensitive method for determination of trace levels of domoic acid (DA) in seawater was developed, based on a magnetic solid-phase extraction (MSPE) followed by high-performance liquid chromatography with tandem mass spectrometry (HPLC–MS/MS). Five kinds of ferrite magnetic nanospheres (MFe 2 O 4 ; M = Fe, Co, Ni, Cu and Zn) were prepared and first used as sorbents for MSPE of DA and removal of salt interference. Under the same extraction and elution conditions, CuFe 2 O 4 magnetic nanospheres provided the best pretreatment performance, which were then characterized in detail. After further optimization of conditions, the developed method showed good linearity (r 2 = 0.9991) with the range of 5–1000 pg mL −1 , low limit of detection (2.5 pg mL −1 ; S/N = 3:1), low limit of quantification (5.0 pg mL −1 ; S/N = 10:1), and good recoveries (86.0–98.1%) with acceptable repeatability (RSD ≤ 6.5%; n = 3) in seawater samples. The results demonstrated that the ferrite magnetic nanospheres are promising sorbents for efficient extraction of highly polar analytes from high ionic strength solutions.
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