title: Performance of dielectric barrier discharge ionization mass spectrometry for pesticide testing: a comparison with atmospheric pressure chemical ionization and electrospray ionization.
abstract: BACKGROUND
  The present study reports on the evaluation of dielectric barrier discharge microplasma ionization (DBDI) for liquid chromatography/high resolution mass spectrometry (LC/HRMS) analyses of pesticide residues in fruit and vegetables. Ionization, fragmentation, analytical performance and matrix effects displayed by LC/DBDI-MS were critically evaluated and compared with both atmospheric pressure chemical ionization (APCI) and electrospray (ESI), using a set of over 40 representative multiclass pesticides.
  
  
  METHODS
  Sample preparation was accomplished using standard QuEChERS procedure and the identification and quantitation of the pesticides tested accomplished by means of LC/MS with a hybrid linear quadrupole ion trap (LIT)-Fourier transform ion cyclotron resonance (FTICR) mass spectrometer operated in full-scan positive ion mode using DBDI, APCI and ESI sources.
  
  
  RESULTS
  The developed LC/DBDI-MS method allowed the screening of 43 pesticides in three different vegetable matrices: apple, orange and tomato. Minor matrix effects (i.e. signal suppression or enhancement ≤20%) were observed in most of the studied compounds: 95%, 70% and 81% of the studied compounds showed minor matrix effects in extracts of apple, orange and tomato, respectively. The results of the analysis of spiked orange extracts showed that the sensitivity obtained with LC/DBDI-MS is appropriate for multi-residue analysis of pesticide residues in fruit and vegetable samples. The limits of quantitation (LOQs) obtained for most of the studied pesticides were in compliance with the European Regulation 396/2005 (and subsequent updates) on food commodities (default maximum residue level of 10 µg kg(-1)).
  
  
  CONCLUSIONS
  Comparative studies with commercial sources demonstrate the suitability of DBDI as an ionization technique for residue analysis, because of the combination of the following two advantages: (1) the use of DBDI provides minimized matrix effects compared with APCI, and (2) improved the detection - in terms of sensitivity - of selected compounds that are not easily ionized by ESI, such as parathion.
authors.affiliation: Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V, Otto-Hahn-Str. 6b, 44227, Dortmund, Germany.
authors.forename: Bienvenida
authors.initials: B
authors.lastname: Gilbert-López
authors.forename: Helma
authors.initials: H
authors.lastname: Geltenpoth
authors.forename: Cordula
authors.initials: C
authors.lastname: Meyer
authors.forename: Antje
authors.initials: A
authors.lastname: Michels
authors.forename: Heiko
authors.initials: H
authors.lastname: Hayen
authors.forename: Antonio
authors.initials: A
authors.lastname: Molina-Díaz
authors.forename: Juan F
authors.initials: JF
authors.lastname: García-Reyes
authors.forename: Joachim
authors.initials: J
authors.lastname: Franzke
mesh_terms: D002851:Chromatography, High Pressure Liquid; D032084:Citrus sinensis / Q000737:chemistry; D005638:Fruit / Q000737:chemistry; D018551:Solanum lycopersicum / Q000737:chemistry; D027845:Malus / Q000737:chemistry; D013058:Mass Spectrometry / Q000379:methods*; D010573:Pesticide Residues / Q000032:analysis / Q000737:chemistry* / Q000302:isolation & purification; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014675:Vegetables / Q000737:chemistry
chemical_list: D010573:Pesticide Residues