Espectrometria de massas ambiente: novas abordagens para análise de pesticidas em alimentos

• Ano de defesa: 2018
• Autor(a) principal: Silva, Igor Pereira da
• Orientador(a): Vaz, Boniek Gontijo
• Banca de defesa: Vaz, Boniek Gontijo, Augusti, Rodinei, Lião, Luciano Morais, Kato, Lucilia, Nascimento, Abadia dos Reis
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Goiás
• Programa de Pós-Graduação: Programa de Pós-graduação em Química (IQ)
• Departamento: Instituto de Química - IQ (RG)
• País: Brasil
• Palavras-chave em Português: Espetrometria de massas ambiente; Pesticidas
• Palavras-chave em Inglês: Paper spray ionization; Leaf spray; Infrared laser ablation sample transfer; Pesticides; Ambient mass spectrometry
• Área do conhecimento CNPq: QUIMICA::QUIMICA ANALITICA
• Link de acesso: http://repositorio.bc.ufg.br/tede/handle/tede/9246

Pesticides are compounds used on fruits and vegetables to avoid damage by pests. Usually, pesticide residue determination in fruits and vegetables has been performed by using gas chromatography coupled to mass spectrometry (GC-MS) and liquid chromatography coupled to mass spectrometry (LC-MS). Both techniques demonstrate excellent analytical performance but require laborious steps of sample preparation prior to instrumental analysis. Ambient mass spectrometry (AMS) is a group of techniques that requires minimal or no sample preparation and emerges as an alternative for analysis of pesticides in food. This work shows three chapters using AMS techniques for analysis of pesticides in fruits or vegetables. In the first approach, paper spray ionization (PSI) and leaf spray (LS) were compared by analyzing the pesticides atrazine, diuron and methomyl in lettuce, kale, basil, cabbage and arugula. Both techniques showed similar analytical performances. The calibration curves were obtained with R2>0.99 and the limits of detection (LOD) and quantification (LOQ) were found in ppb range. In the second approach, a molecularly imprinted polymer (MIP) was coupled to PSI-MS to obtain a selective method. MIP membrane spray ionization was employed for the analysis of diuron and 2,4-dichlorophenoxyacetic acid (2,4-D) in apple, banana and grape extracts. This method demonstrated higher signal intensities for diuron and 2,4-D in comparison to the non-imprinted polymer (NIP). The calibration curves were obtained with R2>0.99 for the pesticides in all fruit extracts, and the LODs were found below 0.60 ppb and LOQs below 2 ppb. The accuracy and precision values were lower than 20% and the values of recovery ranged from 92.5% to 116.9%. In the next chapter, matrix-assisted laser desorption ionization (MALDI) imaging was combined with infrared laser ablation sample transfer (IR-LAST) ambient technique to verify the penetration of the fungicide imazalil in apples. MALDI imaging was used to obtain information on the spatial location of the compound, whereas IR- LAST with electrospray ionization (ESI) was used for quantification. The fungicide was detected in the inner part of the apple one day after its application. The concentration of imazalil in the apple skin was reduced over the days. Seven days after application of the fungicide, a concentration of 0.015 ppm was found six millimeters inside the apple. The penetration rate of imazalil was approximately 1 mm per day.