A uniform magnetic field assisted automated magnetic micro solid-phase extraction for the determination of trace molinate in water and rice samples

In this work, dichlorodiphenylsilane (DCDPS)-modified Fe3O4@SiO2, as a nanomagnetic sorbent, was synthesized
and applied in a uniform magnetic field-assisted automated magnetic micro solid-phase extraction (UMFAMSPE)
procedure. In this regard, a different automatic strategy for magnetic solid-phase extraction was proposed
with the assistance of a uniform magnetic field of 0.5 T, produced by a pair of permanent magnets. To
demonstrate the potential of the method, a trace amount of molinate was determined by ion mobility spectrometry.
According to the data, the detection limit and dynamic range were assessed at 0.03 μg/L and 0.1–7.0
μg/L, respectively. The performance of the procedure was finally demonstrated for determining the analyte in
some real samples (seeded rice, river, and paddy water). The satisfactory relative recovery values in the range of
88 %–109 % reveal the capability of the introduced method. Due to the application of the completely uniform
field to the microcolumn, nanomagnetic sorbents are uniformly distributed throughout the inner surface of the
extraction microcolumn, without requiring frits. The significant achievement of this configuration procedure is
the distribution of the MNPs in microcolumns, creating a larger specific area for extracting analytes. The procedure
eliminates high back pressure, the agglomeration of MNPs, and the preferred pathway channels.