title: [Determination of nineteen organonitrogen pesticides in Paeoniae Radix Alba by capillary electrophoresis-mass spectrometry].
abstract: OBJECTIVE
  To establish a capillary electrophoresis-mass spectrometry(CE-MS) method for the analysis of nineteen organonitrogen pesticides in Paeoniae Radix Alba.
  
  
  METHODS
  CE-MS analysis was performed on a 70 cm X 50 μm fused-silica capillary. The optimal buffer was composed of 1 % formic acid and 15 % methanol(V/V, pH 2.2). The temperature of capillary was controlled at 25 degree. The separation voltage was +20 kV. The optimal MS parameters were as follows: ESI-MS analysis was performed in the positive mode; 90 % methanol containing 0.2 % formic acid with a flow rate of 8 μl·min(-1) was selected as the sheath liquid; the flow rate and temperature of drying gas were 6 L·min(-1) and 250 degree, respectively; The nebulizing gas pressure was set at 5 psig; The optimal values of fragmentor and ESI voltage were 100 V and 5 000 V, respectively.
  
  
  RESULTS
  The nineteen pesticides had good linearity over the testing ranges. The average recoveries were in the range of 80.1 %-108.4 % with RSDs less than 20 % (except ethoxyquin and spiroxamine, those of which were 29.2 % and 22.3 % at 0.01 mg.kg(-1) concentration level). The LODs of nineteen pesticides were 0.503 ≊10.1 μg.kg(-1).
  
  
  CONCLUSIONS
  The method can be used effectively to analyze the nineteen organonitrogen pesticides residue in Paeoniae Radix Alba.
authors.affiliation: College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China.
authors.forename: Xue-chun
authors.initials: XC
authors.lastname: Du
authors.forename: Yi-min
authors.initials: YM
authors.lastname: Xu
authors.forename: Shen
authors.initials: S
authors.lastname: Ji
authors.forename: Xiu-hong
authors.initials: XH
authors.lastname: Mao
authors.forename: Ke
authors.initials: K
authors.lastname: Wang
authors.forename: Shu-Fang
authors.initials: SF
authors.lastname: Wang
mesh_terms: D019075:Electrophoresis, Capillary / Q000379:methods*; D013058:Mass Spectrometry / Q000379:methods*; D029596:Paeonia / Q000737:chemistry*; D010573:Pesticide Residues / Q000032:analysis*
chemical_list: D010573:Pesticide Residues