A fast and sensitive method using high performance liquid chromatography-fluorescence detection (HPLC-FD) and ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) was developed and validated for the determination of avermectins residues in ovine muscle samples. QuEChERS (quick, easy, cheap, effective, rugged and safe) sample preparation based on acetonitrile extraction followed by partitioning with NaCl and Na2SO4 and dispersive solid-phase extraction (d-SPE) clean-up with C18 was applied. Na2SO4 was used instead of MgSO4 due to lower amounts of co-extractives in the final extract. The procedure was validated according to the Commission Decision 2002/657/EC. The method showed determination coefficients (r2) higher than 0.99, recoveries between 93.2 and 124.3% for spike levels between 0.5 and 2.0 times the maximum residues limit (MRL) values. The repeatability and intermediate precision RSD values ranged from 1 to 19%. Decision limits (CCα) and detection capabilities (CCβ) ranged from 10.7 to 59.4 µg kg-1 and 11.4 to 68.8 µg kg-1, respectively. Method performance was successfully evaluated by analyzing real samples and proficiency test with a z-score in the range of ±1.

In this work, a method for multiclass determination of 70 pesticides residues with different properties in drinking water using solid phase extraction (SPE) with polymeric sorbent and determination by gas and liquid chromatography coupled to tandem mass spectrometry (GC-MS/MS and LC-MS/MS) was developed and validated. Different sample volumes, sorbents and elution solvents were evaluated. The best results were obtained using the sorbent Oasis® HLB, sample acidified at pH 2.5 and a mixture of dichloromethane/methanol as eluent. The limit of quantification (LOD) of the method was 0.02 µg L-1 for aldrin, dieldrin and chlordane and 0.5 µg L-1 for the other compounds. Satisfactory accuracy, with recoveries between 70 and 117.3%, and good precision, with relative standard deviation (RSD) values below 19.7% for most of the compounds, were achieved. The validated method was applied to real water samples and results indicated that the proposed method is suitable for the determination of pesticide residues in water samples.

O mel pode apresentar resíduos de pesticidas devido à contaminação das abelhas durante a coleta de pólen e néctar ou por tratamento das colmeias. Assim, a determinação de resíduos de pesticidas em mel é de grande importância, apesar da dificuldade devido à complexidade da matriz. Neste estudo, um novo método para a determinação de pesticidas de diferentes grupos químicos em mel foi desenvolvido e validado. Amostras de mel foram extraídas pelo método QuEChERS modificado e analisados por cromatografia gasosa com detecção por captura de elétrons (GC-ECD). Os resultados de recuperação, avaliados em três níveis de fortificação, foram entre 71 e 119% para a maioria dos compostos, com valores de desvio padrão relativo (RSD) < 20%. O método proposto permite a determinação com limites de detecção entre 3 e 6 µg kg-1, combinando a extração e limpeza do extrato de forma efetiva, com boa sensibilidade e seletividade, e foi aplicado com sucesso na análise de amostras comerciais de mel.

Honey can present pesticide residues due to the contamination of bees during the collection of pollen and nectar or by treatment of hives. Thus, the determination of pesticide residues in honey is of great importance, despite the difficulty due to the complexity of the matrix. In this study a new method for the determination of pesticides from different chemical groups in honey was developed and validated. Honey samples were extracted by modified QuEChERS method and analyzed by gas chromatography with electron capture detection (GC-ECD). Recovery results, evaluated at three spike levels, were between 71 and 119% for most of the compounds, with relative standard deviation (RSD) < 20%. The proposed method enables the determination at limits of detection between 3 and 6 µg kg-1, combining effective extraction and clean-up steps with good sensitivity and selectivity, and was successfully applied to the analysis of commercial honey samples.

Considering the possibility that pesticides used in cattle raising produce residues in milk and cause harm to public health, this study developed a multiresidue method for determination of pesticide residues in bovine milk, using a modified QuEChERS method for sample preparation, and quantification by GC-MS/MS. The method proved to be efficient, resulting in satisfactory recoveries in the range 71.1 to 117.4%, for 45 of the 48 compounds analyzed with RSD values < 17.3%. The method LOD and LOQ were3.0 and 10.0 µg L-1, respectively, except for cyfluthrin which showed 7.5 and 25.0 µg L-1.

Um método eficiente e sensível para a determinação simultânea do inseticida fipronil e seus principais metabólitos fipronil desulfinil, fipronil sulfeto e fipronil sulfona em águas superficiais foi desenvolvido e validado. Fipronil e seus metabolitos foram determinados por cromatografia gasosa com detecção por captura de elétrons (GC-ECD) após uma etapa de pré-concentração empregando extração em fase sólida (SPE). Os parâmetros de validação avaliados incluíram curva analítica e linearidade, limites de detecção (LOD) e de quantificação (LOQ), precisão e exatidão. GC-ECD apresentou uma boa resposta para fipronil e seus metabólitos, e todas as curvas analíticas apresentaram coeficientes de determinação superiores a 0,995. Os LODs do método foram 2,5 ng L-1 para fipronil e 2,0 ng L-1 para cada metabólito. Todos os valores de recuperação variaram de 81,3 a 112,3%, com valores de desvio padrão relativo (RSD) inferiores a 14,2%. O método proposto foi aplicado com sucesso em amostras de água de lavoura de arroz irrigado.

An efficient and sensitive method for simultaneous determination of the insecticide fipronil and its main metabolites fipronil desulfinyl, fipronil sulfide and fipronil sulfone in surface water was developed and validated. Fipronil and its metabolites were determined by gas chromatography with electron capture detection (GC-ECD) after a preconcentration step using solid phase extraction (SPE). The evaluated validation parameters included analytical curve and linearity, limit of detection (LOD) and quantification (LOQ), precision and accuracy. GC-ECD presented a good response for fipronil and its metabolites, and all analytical curves showed determination coefficients higher than 0.995. The LOD values of the method were 2.5 ng L-1 for fipronil and 2.0 ng L-1 for each metabolite. All recovery values were between 81.3 and 112.3%, with relative standard deviation (RSD) values lower than 14.2%. The proposed method was successfully applied to the analysis of water samples from flooded rice fields.

The determination of veterinary drug residues in foods of animal origin is an important issue because of the risk these compounds pose to human health in addition to their persistence and tendency to bioaccumulate. In recent years, significant progress has been made in the area and this review presents the state of the art in sample preparation procedures associated with chromatographic techniques coupled to mass spectrometry for multiresidue determination of veterinary drugs in food of animal origin at concentration levels suitable for the control of residues and contaminants in food.

Este estudo avaliou a degradação do herbicida clomazone em água destilada e de campos de arroz irrigado, através de irradiação UV e sob condições naturais. Após a etapa de pré-concentração por extração em fase sólida (SPE), a concentração remanescente foi determinada por cromatografia líquida de alta eficiência com detecção por arranjo de diodos (HPLC-DAD) e a identificação dos produtos de degradação foi efetuada por cromatografia gasosa com espectrometria de massas (GC-MS). Sob irradiação UV, o clomazone foi degradado mais rapidamente na água destilada que na água de superfície. Na água de irrigação, sob luz solar, o clomazone apresentou tempo de meia-vida médio de 3,2 dias em três safras consecutivas, e após a aplicação a concentração na água permaneceu acima de 0,1 μg L-1 por cerca de 20 dias. Diversos subprodutos, tais como 2-clorobenzaldeído e 2-clorobenzeno metanol, foram identificados por GC-MS, evidenciando que a concentração dos intermediários aumentou no início e então eles também sofreram degradação.

This study evaluated the degradation of the herbicide clomazone in distilled water and from irrigated rice fields, through UV irradiation and under natural conditions. After a solid phase extraction (SPE) as preconcentration step, the remained concentration of clomazone was determined by high performance liquid chromatography with diode array detection (HPLC-DAD) and the identification of the degradation products was achieved by gas chromatography-mass spectrometry (GC-MS). Under UV irradiation, the clomazone was degraded faster in distilled water than in surface water. In irrigated rice water, under sunlight irradiation, clomazone presented a half-life time average of 3.2 days in three consecutive harvests, and after application the concentration in water remained higher than 0.1 μg L-1 for 20 days. Several by-products, like 2-chlorobenzaldehyde and 2-chlorobenzene methanol, were identified by GC-MS, which evidenced that the concentration of intermediates at the begining increase and then they also undergo degradation.

O estudo avalia a degradação do herbicida propanil e de seu principal produto de degradação, a 3,4-dicloroanilina (3,4-DCA), em água de irrigação de lavouras de arroz irrigado no Estado do Rio Grande do Sul, Brasil. Além disso, estima, também, o risco de contaminação das águas de superfície das proximidades. Após uma etapa de extração em fase sólida, a concentração de ambos os compostos foi determinada por cromatografia líquida de alta eficiência com detecção na região do ultravioleta. A confirmação foi realizada por cromatografia gasosa-espectrometria de massas. A concentração de propanil nas amostras de água variou de 0,1 a 3600 µg L-1. O propanil degradou-se rapidamente em 3,4-DCA, sendo que altas concentrações deste produto foram encontradas, variando entre 1,0 e 567,5 µg L-1. Os tempos de meia-vida para o propanil em água sob condições reais nas safras de 2001, 2002 e 2003 foram 18,2, 12,5 e 12,2 h, respectivamente.

This study evaluates the degradation of the herbicide propanil and of its major degradation product, 3,4-dichloroaniline (3,4-DCA) in water from irrigated rice farming in the State of Rio Grande do Sul, Brazil. It also assesses the contamination risk of surrounding surface waters. After a solid phase extraction step, the concentration of both compounds was determined by high performance liquid chromatography with ultraviolet detection. Confirmation was conducted by gas chromatography-mass spectrometry. Concentrations of propanil in water samples varied from 0.1 to 3600 µg L-1. Propanil was degraded very rapidly to 3,4-DCA and high concentrations of this product were found, varying from 1.0 to 567.5 µg L-1 in water. The obtained half-life times for propanil in water under real conditions for the 2001, 2002 and 2003 harvests were 18.2, 12.5 and 12.2 h, respectively.