Banca de DEFESA: Denise Carvalho Mello

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : Denise Carvalho Mello
DATE: 12/09/2023
TIME: 14:00
LOCAL: Sala da Pós-Graduação da Faculdade de Medicina/Plataforma Zoom
TITLE:

Pesticide residues in vegetal herbs -validation of UHPLC-MS/MS methods and analysis

 

KEY WORDS:

dry herbs; pesticides; dithiocarbamates; EBDC; mancozeb; ethylenethiourea; UHPLC-MS/MS

PAGES: 100
BIG AREA: Outra
AREA: Defesa
SUMMARY:

Herbs are used for tea preparation, and as material for phytotherapy medicines, and both are largely used by the population. However, they may contain contaminants and residues that may pose a risk health to consumers, and their levels should be monitored. In this work, UHPLC-MS/MS methods for multiresidue analysis (MMR), ethylenebisdithiocarbamates (EBDC, mancozeb and metiram), a subclass of the dithiocarbamates fungicides, and its degradation product ethylenethiourea (ETU), responsible for chronic toxicity of the EBDC, were validated in different dry herbs. The extraction of samples in the MMR method is performed with acidified acetonitrile (ACN), magnesium sulfate (MgSO4), and sodium acetate (CH3COONa), followed by purification by dispersive solid-phase with secondary primary amine (PSA). Sample preparation for determination of EBDC includes complexation with EDTA in alkaline medium, derivatization to form EBDC-dimethyl using dimethyl sulfate solution in ACN, followed by addition of MgSO4, sodium chloride (NaCl), and PSA. In the ETU method, samples are extracted with ACN, adding L-cysteine, followed by MgSO4, NaCl, and PSA. A mixture of seven plants, which are composed by flower, leaf, stem and/or bark, was used as control for the validation of the methods, which were applied to analyze samples of 33 different herbs. MMR was validated for 65 pesticides, and the limit of quantification (LOQ) ranged from 0.05 to 0.025 mg/kg; 35% of the 75 samples analyzed were positive (≥ the limit of detection, LOD) for at least one pesticide, with carbendazim (up to 1.602 mg/kg), and imidacloprid being the most detected (38.7 and 30.7% of positive samples, respectively). Mancozeb was used to validate the EBDC method, with a LOQ of 0.03 mg/kg (0.02 mg/kg CS2); 16.5% of the 103 analyzed samples were positive (≥ LOD, up to 1.05 mg/kg or 0.59 mg/kg CS2). None of the 89 samples analyzed for ETU (LOQ of 0.03 mg/kg) were positive. Only two of the analyzed pesticides are registered in Brazil for use in the investigated herbs (linuron in chamomile, and methomyl in black mulberry), indicating that good agricultural practices are not being applied in herb cultivation. The daily intake of pesticides through the consumption of the dry herbs analyzed represent a maximum of 5% the pesticide acceptable daily intake (fenitrothion, arnica), which does not represent a potential risk to consumers. In this work, methods for the analysis of pesticide residues in dry medicinal herbs were satisfactorily validated and can be applied to the analysis of different herb types. 

COMMITTEE MEMBERS:
Externa à Instituição - IONARA REGINA PIZZUTTI - UFSM
Externo à Instituição - PETER REMBISCHEVSKI - ANVISA
Externa à Instituição - ANDREIA NUNES OLIVEIRA JARDIM
Interna - 2221666 - ELOISA DUTRA CALDAS
Externa ao Programa - 2865822 - PATRICIA DINIZ ANDRADE - null