A simple and specific method using reversed-phase liquid chromatography coupled with electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) was investigated, which allowed the determination of residues of glyphosate and its metabolite, aminomethylphosphonic acid (AMPA), in soybean samples. An aqueous extraction with liquid-liquid partition followed by protein precipitation was performed before the LC/MS/MS determination. The quantitation of glyphosate and AMPA was performed in positive and negative ESI mode, respectively, using the multiple reaction monitoring (MRM) mode with three transitions for each analyte to enhance the specificity of the method and avoid false positives. The methodology reported in this work is capable of detecting residues of glyphosate and AMPA in soybean samples with limits of quantification of 0.30 and 0.34 mg kg(-1), respectively. This alternative method has throughput advantages such as simpler sample preparation and faster chromatographic analysis.

Com o intuito de monitorar a concentração de ácido fólico (vitamina B9) em amostras de farinha de trigo, um método analítico simples e rápido foi desenvolvido e validado, utilizando a técnica de Cromatografia Líquida de Alta Eficiência com detecção por Espectrometria de Massas do tipo triplo quadrupolo (CLAE-EM/EM). O analito foi ionizado com fonte de ionização por electrospray no modo positivo e o espectrômetro de massas foi operado em modo de aquisição por Monitoramento Múltiplo de Reação (Multiple Reaction Monitoring -MRM), com o propósito de detectar duas trannsições de m/z, uma para quantificação e outra para confirmação. Um total de 83 amostras foram processadas para a validação do método de acordo como guia de procedimentos da Comissão Européia, referência 2002/657/EC, para análise de resíduos em alimentos. A performance do método foi avaliada através da linearidade, exatidão, precisão, sensibilidade e incerteza. O resultado das curvas analíticas na faixa de concentração de 1,0 a 50 µg L -1 apresentaram coeficientes de correlação (r 2 ) de 1,000. A reprodutibilidade do método foi obtida através do cálculo da somatória dos desvios padrão dos resultados de análises "intra-dias" e "inter-dias" e apresentou o valor de 5,6%, para o nível de fortificação de 1,50 µg g -1 . Além disso, dez amostras no nível de fortificação de 1,50 µg g -1 foram extraídas e analisadas com exatidão de 85% e precisão de 3% (coeficiente de variação). A sensibilidade do método foi expressa em limite de decisão (CC ) de 0,06 µg g -1 e capacidade de detecção (CC ) de 0,11 µg g -1 . A incerteza total calculada do método foi de + 0,11 µg g -1 . Diferentes marcas de farinha de trigo brasileiras foram avaliadas e reportadas.In order to monitor the fortification level of folic acid (vitamin B9) in wheat flour samples, we developed and validated a simple and fast analytical method using the liquid chromatography with tandem triple quadrupole mass spectrometry (LC-MS/MS) technique. The compound was ionized by an electrospray source in positive mode. The tandem MS/MS instrument was set in MRM (Multiple Reaction Monitoring) mode to detect two m/z transitions used for quantitation and confirmation purposes. A total of 83 samples were prepared to validate the method according to the regulatory guidelines from the Commission Decision 2002/657/EC for food residues analysis. The method performance was evaluated in regards to linearity, accuracy, precision, sensitivity, and uncertainty. The statistical analysis of the results showed a correlation coefficient (r 2 ) of 1.000 within the concentration range of 1.0 to 50 µg L -1. The method reproducibility of 5.6% was obtained by calculating the standard deviation sum of the intra-day and inter-day analysis at a fortification level limit of 1.50 µg g -1 of folic acid. In addition, ten blank spiked samples at the fortification level limit were extracted and analyzed with an accuracy of 85% and a precision of 3% (coefficient of variation). The method sensitivity was expressed in decision limit (CC ) of 0.06...

Atualmente, existe uma preocupação mundial sobre qualidade de vida e um dos requisitos mais importantes é ingerir alimentos seguros e nutritivos. A administração de antibióticos em gado para tratamento de diversas doenças infecciosas tem contribuído para a contaminação do leite industrializado. Por isso, o principal objetivo deste trabalho foi desenvolver um método simples e rápido para identificar e quantificar quatorze antibióticos de diferentes classes em leite, dentre estes: cinco β-lactâmicos, quatro sulfonamidas, três tetraciclinas, um macrolídeo e uma cefalosporina, utilizando sistema de CLAE em modo reverso de eluição com ionização por electrospray e detecção por espectrometria de massas do tipo triploquadrupolo (MS/MS). Esta técnica utilizada em modo de aquisição Monitoramento Múltiplo de Reação (Multiple Reaction Monitoring -MRM) permitiu a determinação dos compostos propostos na faixa de concentração de 0,75 a 375 µg L -1 , com coeficientes de linearidade (r) maiores do que 0,9960, seletividade, sensibilidade e velocidade, com tempo total de análise menor do que 10 minutos. Os compostos dicloxacilina e eritromicina apresentaram o maior e menor resultado de limite de decisão (ccα) igual a 0,05 e 9,77 µg L -1 , respectivamente. Em geral, os resultados de recuperação foram de 65 a 125%, com valores de desvio padrão de 2,0 a 15%. Este método também foi aplicado para avaliar a qualidade de diferentes marcas de leite integral disponíveis no mercado brasileiro.There is a common worldwide concern about the quality of life and one of the most important requirements is to ingest safe and nutritious food. The administration of antibiotics in cattle to treat several infectious diseases has contributed to the contamination of industrialized milk. The goal of this work was to develop a simple and fast method to identify and quantify fourteen antibiotics from different classes in milk, including five β-lactams, four sulfonamides, three tetracyclines, one macrolide and one cephalosporin, using reversed-phase liquid chromatography with electrospray ionization and triple quadrupole mass spectrometry (MS/MS). This technique used Multiple Reaction Monitoring (MRM) acquisition mode to allow the determination of the proposed compounds in the concentration range from 0.75 to 375 µg L -1 , within coefficient of linearity (r) higher than 0.9960, selectivity, sensitivity, and speed, with analysis time less than 10 minutes. Dicloxacillin and erythromycin showed the lower and higher decision limits (ccα) results of 0.05 and 9.77 µg L -1 , respectively. Overall, the recoveries results ranged from 65 to 125%, with standard deviation values from 2.0 to 15%. This method was also applied to evaluate the quality of different fat milk brands offered in the Brazilian market.

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496by mass or tandem mass spectrometry, especially by using electrospray ionization, because they are very polar and easily ionized on this technique. However, just a few methods using mass or tandem mass spectrometry coupled with liquid chromatography have been found in the literature for glyphosate and AMPA analysis. In most of published papers, pre and postcolumn derivatization procedures were employed to analyze the compound derivative by fluorescence detection (Sancho et. al. 1996; Hogendoon et. al. 1999). Vreeken and co-workers developed an analytical method to analyze glyphosate, AMPA and glufosinate in water samples using reversed phase liquid chromatography separation after pre-column derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl) and detection by tandem mass spectrometry (Vreeken et. al. 1998). Bauer and co-workers detected glyphosate and AMPA in water samples using ion chromatography followed by electrospray with single quadrupole mass spectrometry detection. (Bauer et. al. 1999). The ion chromatography separation without derivatization was also used by Granby and co-workers after clean-up on reversed phase column to analyze glyphosate and AMPA through electrospray ionization/tandem mass spectrometric analysis (Granby et. al. 2003). Goodwin and coworkers studied the electrospray negative ion fragmentation pathways of glyphosate and AMPA using an ion-trap mass spectrometer . Some other methods found in the literature to analyze glyphosate and AMPA include: capillary electrophoresis (Cikalo et. al. 1996), ion chromatography with conductivity detection (Zhu, et. al. 1999), ion chromatography with fluorescence detection (Patsias et. al. 2001), gas chromatography (Hudzin et. al. 2002), immunoassays (González-Martinez et. al. 2005), nuclear magnetic resonance (Deen et. al. 2002) and integrated pulse amperometry (Ji-Ye et. al. 2001). In this work, we investigated the potential of reversed phase liquid chromatography coupled with electrospray tandem mass spectrometry (LC-ESI/MS/MS) for the quantification of glyphosate and AMPA in soybean spiked samples. In this approach, the compounds were analyzed without derivatization procedures using calibration curves prepared in the matrix, after a simple sample extraction and liquid-liquid partition followed by protein precipitation step with organic solvent to minimize the complexity of the sample. The mobile phase composition and the matrix effects were also investigated to validate the method using a high flow gradient program in a total run time of four minutes for each analyte. Experimental Chemicals and standardsGlyphosate and AMPA standards were obtained from Sigma-Aldrich (Steinheim, Germany). Methanol and dichloromethane HPLC-grade solvents were purchased from J. T. Baker (Deventer, The Netherlands) and ammonium carbonate P.A. was obtained from Merck (Darmstadt, Germany). Purified water was obtained on EASYpure RF System from Barnstead (Dubuque, IA, USA). The stock solutions of glyphosate and AMPA at 500 mg L -1 were prepared by dissolution of t...