title: Revisiting quick, easy, cheap, effective, rugged, and safe parameters for sample preparation in pesticide residue analysis of lettuce by liquid chromatography-tandem mass spectrometry.
abstract: A new analytical method using a quick, easy, cheap, effective, rugged, and safe (QuEChERS) procedure for multi-residue determination of 16 multiclass pesticides in five different types of lettuce was developed using high-performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry. The QuEChERS procedure was optimized in terms of extractor solvent, partitioning salts and clean-up salts, through recovery, gravimetric analysis and matrix-effect studies. Microwave extraction and the use of disposable pipette extraction in the clean-up step were also tested, providing interesting alternatives to the traditional QuEChERS method, depending on the pesticides properties. The use of a laboratory-made phenyl-type sorbent, based on silica and poly(2-phenylpropyl)methylsiloxane, was studied in the clean-up step, presenting promising results as a substitute for primary secondary amine (PSA). The optimized QuEChERS method was defined employing acetonitrile, citrate buffer and clean-up with PSA, MgSO4and graphitized carbon black. The method developed was validated according to Document SANTE/11945/2015 and proved to be selective, accurate and precise, obtaining limits of quantification from 5μgkg-1and recoveries in the range of 70-120% with relative standard deviation≤20%. The method was applied on 14 real samples from commercial markets in Brazil and 21% of the samples analyzed presented irregularities, according to local pesticides regulations.
authors.affiliation: Instituto de Química, Universidade Estadual de Campinas, Caixa Postal 6154, CEP 13084-971 Campinas, SP, Brazil.
authors.forename: Fernanda
authors.initials: F
authors.lastname: Ribeiro Begnini Konatu
authors.affiliation: Instituto de Química, Universidade Estadual de Campinas, Caixa Postal 6154, CEP 13084-971 Campinas, SP, Brazil.
authors.forename: Márcia Cristina
authors.initials: MC
authors.lastname: Breitkreitz
authors.affiliation: Instituto de Química, Universidade Estadual de Campinas, Caixa Postal 6154, CEP 13084-971 Campinas, SP, Brazil. Electronic address: icsfj@iqm.unicamp.br.
authors.forename: Isabel Cristina
authors.initials: IC
authors.lastname: Sales Fontes Jardim
mesh_terms: D000097:Acetonitriles; D001938:Brazil; D002851:Chromatography, High Pressure Liquid; D018545:Lactuca / Q000737:chemistry*; D010573:Pesticide Residues / Q000032:analysis*; D012822:Silicon Dioxide; D012833:Siloxanes / Q000737:chemistry*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D000097:Acetonitriles; D010573:Pesticide Residues; D012833:Siloxanes; C000620391:poly(2-phenylpropyl)methylsiloxane; D012822:Silicon Dioxide; C032159:acetonitrile
keywords: Lettuce; Liquid chromatography; Pesticides; QuEChERS; Tandem mass spectrometry