Determination of selenium in serum in the presence of gadolinium with ICP-QQQ-MS.
Gadolinium (Gd)-based magnetic resonance imaging (MRI) contrasting agents interfere with the determination of selenium (Se) when analysed by single quadrupole inductively coupled plasma-mass spectrometry (ICP-MS). This paper demonstrates that an ICP-triple quadrupole-MS (ICP-QQQ-MS) with oxygen mass shift overcomes Gd(++) interference on Se(+) and mitigates typically encountered matrix and spectral based interferences. Normal human serum was diluted in a solution containing isopropanol, EDTA, NH4OH and Triton X-100. Samples were unspiked (control) serum; serum spiked with 0.127 μmol L(-1) Se or 127 μmol L(-1) Gd; and serum spiked with both 0.127 μmol L(-1) Se and 127 μmol L(-1) Gd. Consideration of collision/reaction gases and conditions for interference mitigation included helium (He); a 'low' and 'high' hydrogen (H2) flow, and oxygen (O2). The instrument tune for O2 was optimised for effective elimination of interferences via a mass shift reaction of Se(+) to SeO(+). The ICP-QQQ-MS was capable of detecting trace (>9.34 nmol L(-1)) levels of Se in serum in the presence of Gd in our simulated post-MRI serum sample. The multi-tune capabilities of the ICP-QQQ-MS may be adapted to eliminate other specific isobaric interferences that cause false positive results in other analyses where the analyte is confounded by doubly charged and/or polyatomic species.
Elemental Bio-imaging Facility, University of Technology Sydney, Broadway, New South Wales 2007, Australia. philip.doble@uts.edu.au.
David P
DP
Bishop
Dominic J
DJ
Hare
Fred
F
Fryer
Regina V
RV
Taudte
Barbara R
BR
Cardoso
Nerida
N
Cole
Philip A
PA
Doble
D001774:Blood Chemical Analysis / Q000295:instrumentation / Q000379:methods*; D005682:Gadolinium / Q000737:chemistry*; D006801:Humans; D013058:Mass Spectrometry / Q000295:instrumentation / Q000379:methods*; D010100:Oxygen / Q000737:chemistry; D012643:Selenium / Q000097:blood*
D005682:Gadolinium; D012643:Selenium; D010100:Oxygen