title: Direct determination of methyl parathion insecticide in rice samples by headspace solid-phase microextraction-gas chromatography-mass spectrometry.
abstract: BACKGROUND
  The organophosphorus insecticides, especially those based on methyl parathion as active principle, have been used extensively in the protection of rice in Maranhão State, in the north-east of Brazil. This paper describes the optimisation of a solid-phase microextraction (SPME) procedure in confined atmosphere (headspace, HS) for the determination of methyl parathion in rice organic samples by gas chromatography with mass spectrometry detection (GC/MS).
  
  
  RESULTS
  The proposed HS-SPME-GC/MS method has been shown to be appropriate for direct analysis of the insecticide in polished rice, with satisfactory results for the following parameters: linearity (correlation coefficient 0.9985), sensitivity (LOD and LOQ of 0.026 and 0.078 µg kg(-1) respectively), precision (coefficients of variation between 6.1 and 22.4%) and accuracy (recoveries varying from 73.2 to 90.0%). Although the efficiency of the proposed GC/MS does not differ statistically (P < 0.05) from the conventional GC/NPD method, given its low cost, speed and also the fact that a minimum volume of toxic effluent is generated, this method can be considered an on-line procedure based on green chemistry.
  
  
  CONCLUSIONS
  Thus, the analytical methodology satisfies the minimum requirements for control of residues of such insecticides in rice samples destined for human consumption.
authors.affiliation: Núcleo de Análise de Resíduos de Pesticidas - NARP, Departamento de Tecnologia Química, CCET, Universidade Federal do Maranhão, Bacanga, São Luís, Maranhão, Brazil.
authors.forename: Darlan Ferreira
authors.initials: DF
authors.lastname: da Silva
authors.affiliation: Núcleo de Análise de Resíduos de Pesticidas - NARP, Departamento de Tecnologia Química, CCET, Universidade Federal do Maranhão, Bacanga, São Luís, Maranhão, Brazil.
authors.forename: Francisco Eduardo
authors.initials: FE
authors.lastname: Paiva Silva
authors.affiliation: Núcleo de Análise de Resíduos de Pesticidas - NARP, Departamento de Tecnologia Química, CCET, Universidade Federal do Maranhão, Bacanga, São Luís, Maranhão, Brazil.
authors.forename: Fernanda Gabrielle S
authors.initials: FG
authors.lastname: Silva
authors.affiliation: Núcleo de Análise de Resíduos de Pesticidas - NARP, Departamento de Tecnologia Química, CCET, Universidade Federal do Maranhão, Bacanga, São Luís, Maranhão, Brazil.
authors.forename: Gilvanda Silva
authors.initials: GS
authors.lastname: Nunes
authors.affiliation: Faculty of Medicine, Transilvania University of Brasov, Braşov, Romania.
authors.forename: Mihaela
authors.initials: M
authors.lastname: Badea
mesh_terms: D002800:Cholinesterase Inhibitors / Q000032:analysis; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D007306:Insecticides / Q000032:analysis; D008743:Methyl Parathion / Q000032:analysis*; D012275:Oryza / Q000737:chemistry*; D010573:Pesticide Residues / Q000032:analysis*; D052617:Solid Phase Microextraction / Q000379:methods*
chemical_list: D002800:Cholinesterase Inhibitors; D007306:Insecticides; D010573:Pesticide Residues; D008743:Methyl Parathion
keywords: GC/MS; methyl parathion; organophosphorus pesticides; solid-phase microextraction