Electronic Supplementary Material
Hybrid nanoparticles based on magnetic multiwalled carbon nanotube-nanoC18SiO2
composites for solid phase extraction of mycotoxins prior to their determination by LC-MS
Virginia Moreno1,2, Mohammed Zougagh2,3, Ángel Ríos1,2*
1Department
of Analytical Chemistry and Food Technology, University of Castilla-La Mancha, 13071
Ciudad Real, Spain
2Regional
Institute for Applied Chemistry Research (IRICA), 13071 Ciudad Real, Spain
3Castilla-La
Mancha Science and Technology Park, 02001 Albacete, Spain
____________________
*
Corresponding author. Tel.: +34 926 295232; fax: +34 926 295318. E-mail address: Angel.Rios@uclm.es
Optimization of HPLC-MS
Mycotoxin analysis is commonly based on the use of HPLC involving different columns
depending on the physical and chemical structure of the mycotoxin. Therefore, the
optimization of the HPLC-MS method was the first task. First, different types of
columns were tested for the separation of the group of mycotoxins. A C18 column
working in the reverse phase mode was the best choice, with a particle size of 2.7 μm
of
diameter.
Moreover,
different
mobile
ternary
phases,
containing
acetonitrile/methanol/water and with different concentrations of ammonium acetate
were tested. A water / methanol / acetonitrile (H2O: MeOH: ACN = 35:55:10, v / v, 15
mM ammonium acetate, pH 7.4) was selected as the optimum mobile phase because
good retention times and sensitivity for the separation of the analytes were obtained.
Both retention time and peak width decreased as the flow-rate increased for all the
compounds. However, a lower resolution was observed for the higher flow-rates. Thus,
a flow-rate of 0.4 mL min-1 was chosen for further works. Under these experimental
conditions, the retention time values (min ± SD, n=10) were as follows: 13.8 ± 0.1 (β-
1
ZAL), 15.9 ± 0.2 (β-ZOL), 21.9 ± 0.1 (α-ZAL), 24.2 ± 0.2 (α-ZOL), 28.4 ± 0.2 (ZAN) and
31.0 ± 0.2 (ZON).
MS parameters were optimized by the direct introduction of the multiple standard
samples within the same run. This approach was used for the rapid optimization of MS
parameters such as drying gas flow, temperature and nebulizer pressure (which
depend on the mobile phase and flow rate, as well as the ionization mode) and
fragmenting voltage (which depends on the structure of the compound). The optimal
operating parameters in positive ion mode were: drying glass flow 13 mL min-1, drying
gas temperature 350 °C, nebulizer pressure 60 psi, and fragmenting voltage 3500 V.
Single ion monitoring (SIM) was used to quantify the target analytes using external
calibration. Previously, full scan mode (SCAN) was used to identify the analytes by
matching the retention time and mass spectra with standards. The main mass spectra
ions were 345.1 (α-ZAL and β-ZAL), 343.1 (α-ZOL and β-ZOL), 321.1 (ZAN) and 319.2
(ZON).
2