title: Fast screening of pesticide multiresidues in aqueous samples by dual stir bar sorptive extraction-thermal desorption-low thermal mass gas chromatography-mass spectrometry.
abstract: A method for fast screening of pesticide multiresidues in aqueous samples using dual stir bar sorptive extraction-thermal desorption-low thermal mass gas chromatography-mass spectrometry (dual SBSE-TD-LTM-GC-MS) has been developed. Recovery of 82 pesticides - organochlorine, carbamate, organophosphorous, pyrethroid and others - for the SBSE was evaluated as a function of octanol-water distribution coefficients (log K(o/w): 1.7-8.35), sample volume (2-20 mL), salt addition (0-30% NaCl), and methanol addition (0-20%). The optimized method consists of a dual SBSE performed simultaneously on respectively a 20-mL sample containing 30% NaCl and a 20-mL sample without modifier (100% sample solution). One extraction with 30% NaCl is mainly targeting solutes with low K(o/w) (log K(o/w)<3.5) and another extraction with unmodified sample solution is targeting solutes with medium and high K(o/w) (log K(o/w)>3.5). After extraction, the two stir bars are placed in a single glass desorption liner and are simultaneously desorbed. The desorbed compounds are analyzed by use of LTM-GC-MS with fast temperature programming (75 degrees C min(-1)) using a 0.18 mm i.d. narrow-bore capillary column and fast scanning (10.83 scan s(-1)) using quadrupole MS. The method showed good linearity (r(2)>0.9900) and high sensitivity (limit of detection: <10 ng L(-1)) for most of the target pesticides. The method was applied to the determination of pesticides at nanograms per liter levels in river water and brewed green tea.
authors.affiliation: Gerstel K.K., 2-13-18 Nakane, Meguro-ku, Tokyo 152-0031, Japan. nobuo_ochiai@gerstel.co.jp
authors.forename: Nobuo
authors.initials: N
authors.lastname: Ochiai
authors.forename: Kikuo
authors.initials: K
authors.lastname: Sasamoto
authors.forename: Hirooki
authors.initials: H
authors.lastname: Kanda
authors.forename: Sadao
authors.initials: S
authors.lastname: Nakamura
mesh_terms: D001628:Beverages / Q000032:analysis*; D005591:Chemical Fractionation / Q000379:methods*; D005618:Fresh Water / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D010573:Pesticide Residues / Q000032:analysis*; D015203:Reproducibility of Results; D012965:Sodium Chloride / Q000737:chemistry; D013696:Temperature
chemical_list: D010573:Pesticide Residues; D012965:Sodium Chloride