A new magnetic functionalized material based on graphene oxide magnetic nanoparticles (MGO)
was designed and characterized in order to develop a magnetic solid phase extraction method
(MSPE) to enrich both inorganic and organic arsenic species in environmental waters. A FIA system
is used to preconcentrate the arsenic species simultaneously, while the ultra-trace separation and
determination of arsenobetaine (AsBet), cacodylate, As(III) and As(V) species have been achieved
by high performance liquid chromatography coupled to inductively coupled plasma mass
spectrometry (HPLC-ICP-MS) technique. The sample is introduced in the FIA system where the
MSPE takes place, and 1 ml of eluent is collected in a chromatographic vial. After preconcentration,
the vial is introduced in the autosampler of HPLC-ICP-MS. Therefore, preconcentration and
separation/determination processes are automatic and conducted separately (Figure 1). The
strategy of this work was focused on the compatibility between the MSPE eluent and the mobile
phase of HPLC column system, resulting in an efficient and reliable semiautomatic
preconcentration and detection of inorganic and organic arsenic speciation. To the best of our
knowledge, this is the first method combining an online MSPE and HPLC-MS, and one of the first
using a magnetic nanomaterial based on MGO for online MSPE. Under the optimized conditions,
the preconcentration factors obtained for AsBet, cacodilate, As(III) and As(V) with 12 mL sample
solution were 4, 12, 6 and 19, respectively. The LODs for the arsenic species were AsBet 7 ng L -1,
cacodylate 0.4 ng L-1, As(III) 1.0 ng L-1 and As(V) 0.2 ng L-1 and RSDs < 5%. The developed method
was validated by analyzing tap water, well water and seawater samples, and Certified Reference
Materials; fortified lake water TMDA 64.3 and seawater Cass-6 NRC, promising for routine
monitoring of arsenic species in environmental water
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