RESUMO
Dithiocarbamates are a class of fungicides widely used in many countries. In this study, methods for determining the ethylene-bis-dithiocarbamate (EBDC) subclass, and their degradation product ethylenethiourea (ETU) were validated by UHPLC-MS/MS in different types of dry herbs, which can be used as food and/or medicinal purposes. Mancozeb was used in the validation of the EBDC method, where it was initially complexed with EDTA, derivatized, extracted with dimethyl sulfate in acetonitrile, magnesium sulfate (MgSO4), and sodium chloride (NaCl), and then purified using primary secondary amine (PSA). In the ETU method, L-cysteine hydrochloride monohydrate was added to the samples before extraction with acetonitrile, MgSO4, and NaCl, followed by purification with PSA. A pesticide-free blend of seven herbs (boldo, artichoke, "espinheira-santa", cat's claw, senna, chamomile, and cascara buckthorn) comprising distinct parts of the plants (leaves, bark, flowers and/or stems) was used as a control for method validation. Recoveries ranged from 79 to 113% for EBDC and 81 to 109% for ETU. Repeatability and intermediate precision were <20% for both methods. The limit of quantification was 0.03 mg kg-1 for EBDC (0.02 mg kg-1 of CS2) and ETU. The limit of detection (LOD) was set at 1/3 of the LOQ (0.01 mg kg-1 for both analytes). In total, 103 samples of 33 different dry herbs were analyzed, of which 19.4% were positive for EBDC (≥LOD), but no ETU residues were found in any of the analyzed samples. Given the absence of registered dithiocarbamates for use in the investigated herbs in Brazil, the positive results suggest potential illegal pesticide use or cross-contamination, especially considering the low concentrations detected in most samples. Although exposure to EBDC through the consumption of medicinal herbs from positive samples did not indicate a health risk to consumers, these plants must be monitored to prevent illicit pesticide usage, particularly when the herbs are intended for therapeutic purposes.
Assuntos
Etilenotioureia , Espectrometria de Massas em Tandem , Cromatografia Líquida de Alta Pressão/métodos , Espectrometria de Massas em Tandem/métodos , Etilenotioureia/análise , Etilenotioureia/química , Fungicidas Industriais/análise , Fungicidas Industriais/química , Etilenobis (ditiocarbamatos)/química , Etilenobis (ditiocarbamatos)/análise , Limite de Detecção , Resíduos de Praguicidas/análise , Resíduos de Praguicidas/química , Reprodutibilidade dos Testes , Plantas Medicinais/químicaRESUMO
Dithiocarbamates are a non-systemic group of pesticides widely used to protect crops from fungal diseases. The current methodology used by monitoring laboratories to determine dithiocarbamates in food involves the analysis of CS(2) generated after hydrolysis of the compound present in the sample. This method does not identify the origin of the CS(2) detected, which may or may not be related to the presence of pesticides leading to a potential overestimation of the dietary dithiocarbamate intake. In this paper, 520 food samples (papaya, banana, apple, strawberry, orange, potato, tomato, rice and dry beans) collected in the local market of the Federal District, Brazil, were analyzed for dithiocarbamate content. Detectable levels (> or =10.10 mg/kg CS(2)) were found in 60.8% of the samples, with the highest levels (up to 3.8 mg/kg) found in strawberry, papaya and banana. No residues were found in rice (polished) and only one dry bean sample had detectable levels of the fungicides. Detectable residues were found in the pulp of banana, papaya (including the seeds) and orange (50-62% of the analyzed samples). An exposure assessment, based on dithiocarbamate levels detected in the food crops analyzed in this study, confirms that the intake of dithiocarbamates through food consumption in the country does not represent a health risk to consumers, i.e., the estimated daily intake is less than the acceptable daily intake. Furthermore, the implementation of more selective methodologies to individually analyze these compounds in food monitoring programs in Brazil is not necessary.
Assuntos
Qualidade de Produtos para o Consumidor , Etilenobis (ditiocarbamatos)/análise , Contaminação de Alimentos/análise , Fungicidas Industriais/análise , Resíduos de Praguicidas/análise , Brasil , Produtos Agrícolas/química , Etilenobis (ditiocarbamatos)/toxicidade , Análise de Alimentos , Fungicidas Industriais/toxicidade , Humanos , Concentração Máxima Permitida , Resíduos de Praguicidas/toxicidade , Medição de RiscoRESUMO
Dithiocarbamates are a class of fungicides extensively used in many crops worldwide. The current residue definition of dithiocarbamates in food for compliance with maximum residue limits, at national and international levels, is total residues arising from the use of any or each dithiocarbamate fungicide, determined as CS(2). The analytical method most frequently used to analyze dithiocarbamate residues in food for monitoring purposes was proposed more than 30 years ago. In this method, total dithiocarbamates are decomposed to CS(2), which is purified and reacted with a cupric reagent. The yellow complex formed is quantified by spectrophotometry. In this paper, a new reaction system for the purification and complexation of CS(2) is proposed. The new system is less fragile than the traditional design, is easier to assemble, and allows for a higher sample throughput, in addition to being of low cost. Recovery of added mancozeb, thiram, or ziram (0.15-8.0 mg/kg) in rice, beans, apple, banana, orange, papaya, tomato, cucumber, and potato ranged from 82 to 120%, with relative standard deviations from 0 to 10% (n = 3 or 5). Analysis of apple, tomato, and papaya samples with field-incurred dithiocarbamate residues showed comparable results using both the traditional and the new reaction systems.
Assuntos
Dissulfetos/química , Etilenobis (ditiocarbamatos)/análise , Análise de Alimentos/métodos , Fungicidas Industriais/análise , Resíduos de Praguicidas/análise , Espectrofotometria/métodos , Fabaceae/química , Frutas/química , Oryza/química , Verduras/químicaRESUMO
Foram recolhidas 466 amostras de 30 diferentes espécies de hortaliças e frutas destinadas à comercializaçäo, a fim de se determinar o teor de resíduos de fungicidas ditiocarbamatos (Mancozeb, Maneb, Propineb, Tiram e Zineb). As amostras foram coletadas junto a fontes produtoras, em uma regiäo tipicamente agrícola do Estado do Rio de Janeiro. Para as determinaçöes analíticas foi utilizado um método baseado na reaçäo colorimétrica do dissulfeto de carbono liberado pela hidrólise ácida dos fungicidas. Do total de amostras analisadas, 63% apresentaram resíduos, sendo que 24% dessas continham níveis acima dos toleráveis pela legislaçäo vigente. Dentre as 30 culturas analisadas, as hortaliças folhosas apresentaram maior incidência de contaminaçäo (70-100%). A alface e a salsa apareceram como as culturas mais afetadas, com níveis de resíduos superiores a 50% dos limites de tolerância, seguidas pela cenoura (47,4%) e tomate (38,2%). A batata-doce e o nabo näo apresentaram resíduos. É importante o monitoramento de resíduos de ditiocarbamatos, pois apesar de apresentarem baixa toxicidade, podem ser precursores de etilenotiuréia, substância de açäo cancerígena mutagênica e teratogênica