Abstract Workflows based on gas and liquid chromatography coupled to mass spectrometry for the identification of toxic pyrrolizidine alkaloids present in plants were developed and applied to Echium plantagineum L., Boraginaceae, extracts. GC–MS based determinations need reduction and derivatization steps prior to MS analysis, which is performed using a Full Scan and Single Ion Monitoring sequence for screening, identification and quantification purposes. The LC–(ESI)–MS/MS determination was performed directly from the extract without derivatization. Acetyl lycopsamine, echimidine, echimidine N-oxide, echiumine, echiumine N-oxide, lycopsamine, lycopsamine N-oxide, 7,9-ditigloylretronecine N-oxide and a not reported PA of m/z 466, were identified and quantified in E. plantagineum extracts, through three operating modes of LC-QTRAP: precursor ion scan, enhanced product ion scan and multiple reaction monitoring. Precursor ion scan detects all the ions that give rise to a daughter ion at m/z 120, the presence of the parent pyrrolizidine alkaloid is confirmed through its MS2 spectrum (enhanced product ion) and quantified by multiple reaction monitoring. These workflows are general approaches to study chemical families using GC/LC-MS. For extracts suspicious of containing pyrrolizidine alkaloids, they are suitable tools for the quality and safety control of food, feed as well as phytotherapeutics.

Abstract Microwave Assisted Extraction and a modified CEN-QuEChERS methodology were evaluated as extraction and clean up procedures for the simultaneous analysis of 42 organophosphate pesticides in yerba mate (Ilex paraguaiensis). The obtained extracts were analyzed by gas chromatography using a flame photometric detector. Linearity, recovery percentages, relative standard deviations, detection and quantification limits and matrix effects were determined according to DG-SANCO guidelines for both methods. At 0.2 and 0.5 mg/kg the evaluated methods showed percentages recoveries between 70 and 120% for most of the analytes. Using Microwave Assisted Extraction methodology, 33 pesticide residues could be properly analyzed whereas only 27 could be determined with the proposed modified QuEChERS. All relative standard deviation were below 18% except for omethoate and disulfoton sulfone when evaluated by the modified QuEChERS. The limits of detection in both methodologies were 0.2 mg/kg for most of the analyzed compounds. The average detection limit for QuEChERS was 0.04 mg/kg. For 19 of the analytes determined through Microwave Assisted Extraction the lowest validated level were 0.004 mg/kg. Signal suppression/enhancement was observed for most of the pesticides, thus matrix-matched calibration curves were used for quantification. The Microwave Assisted Extraction and QuEChERS procedures studied could detect the organophosphate pesticides above the MRL fixed for "mate" by the European Union. They have been successfully applied for the determination of organophosphate pesticide residues in commercial samples and the positives were confirmed through GC–(ITD)-MS.

El monitoreo de residuos de pesticidas en miel es importante debido al riesgo potencial que estos representan para la salud y porque ambientalmente permite obtener información de los pesticidas que han sido usados en los cultivos alrededor de la colmena. Para que los resultados tengan relevancia real es importante elegir cuidadosamente cuáles pesticidas monitorear. La selección de los 41 pesticidas evaluados se realizó en base a la probabilidad de ser encontrados en miel y productos de la colmena, determinada mediante la frecuencia de aparición de muestras positivas en la bibliografía y en la base de datos pesticides-online. Se consideraron además datos recientes de la importación de pesticidas en Uruguay. Se presenta una simple variación del método QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) para la determinación de residuos de pesticidas en miel. Se evaluaron dos métodos de clean-up: freeze-out (extracto a -20 ºC durante 15 h) y d-SPE (Extracción en Fase Sólida dispersiva) utilizando como sorbente PSA (Primary and Secondary Amine). Los pesticidas fueron determinados por LC-MS/MS (QTrap) en modo positivo y negativo. Las recuperaciones estuvieron entre 81-111% para el clean-up dispersivo con excepción de cinco pesticidas ácidos que si se recuperaron al realizar freeze-out (recuperaciones entre 80-114% con excepción de tres pesticidas). Los porcentajes de DER (Desviación Estándar Relativos) fueron menores a 16% en un mismo día y menores a 20% entre distintos días para la mayoría de los pesticidas. Todos los pesticidas presentaron buenas linealidades con R2>0,99 en el rango 0,01-0,4 mg/L. La mayoría de los pesticidas presentan límites de cuantificación de 0,01mg/kg que es el menor límite máximo de residuos establecido por la Unión Europea para miel. Este método se ajusta al doble objetivo de evaluar la calidad de las mieles uruguayas, cumpliendo con conceptos de seguridad alimentaria, facilitar el comercio internacional así como encaminar los intentos de utilizar la colmena como bioindicador de calidad ambiental de una región

Monitoring of pesticide residues in honey is important due to the risk they pose to human health, but also from an environmental point of view, because they provide relevant data on the pesticides that have been used in the hive surroundings. Which pesticides are monitored is crucial for the real significance of the results obtained. The selection of the 41 pesticides employed in this study was based on their relevance for bee products as reflected by the frequency of residue findings in the literature and the pesticides-online database. Recent data concerning the import of pesticides in Uruguay were also considered. A simple variation of the QuEChERS method (Quick, Easy, Cheap, Effective, Rugged and Safe) for the pesticide multiresidue analysis of honey is presented. Two clean-up methods were evaluated: freeze-out (extract placed at -20 ºC for 15 h) and d-SPE (dispersive Solid Phase Extraction) using PSA (Primary and Secondary Amine) as sorbent. Pesticides were determined by LC-MS/MS (QTrap) in positive and negative mode. Recoveries were between 81-111 % for the dispersive clean-up except for five acidic pesticides which were recovered by freezing-out (recoveries between 80-114% except for three pesticides). RSD percentages (Relative Standard Deviation) were less than 16% in one day and less than 20% between different days for most of the studied pesticides. All pesticides showed good linearity, with R2> 0.99 in the range 0.01-0.4 mg/L. Most of the studied pesticides have a limit of quantification of 0.01 mg/kg which is the lowest maximum residue limit set by the European Union for honey. This method serves the double purpose of evaluating the quality of Uruguayan honeys, in terms of food safety with commerce exchange parameters, as well as an input provider for the use of the hive as a bioindicator of environmental quality of a region.

Morphological variation in type IV trichomes in Ss and Ng was studied through SEM. The differences can be related to chemical differences in the excreted sugar esters. Ng trichomes exude two fractions, one of glucose tri-esters and the other one of sucrose tetra-esters, in a 3:7 ratio. The main acid found forming these esthers, is 3-methylvalerianic acid, in consonance to those secreted by other Solanaceae. Esters from Ss are novel structures, which can also be separated into three fractions, two of arabinoxylans, and the other one of arabinose, all glycosilated with β-hydroxipalmitic acid and sterified with the C12-C16 acids. All five fractions have antifungic activity at μg/cm² concentrations, both against common and mycotoxigenic fungi, such as A. niger, A. flavus, P. chrysogenum y P. expansum. A. flavus does not grow in the presence of the SE of Ss and is not insensible to those from Ng, but these last are more effective in the inhibition of P. expansum, the other mycotoxigenic fungi studied. The differential antifungal activity observed gives the plant protection against a wide spectrum of fungi, resulting in a better adaptation to the environment. Both plants are common weeds, with the potential of contributing to germplams lines in the improvement programmes of crops such as L. esculentum, and their extracts can be used as natural fungicides to protect crops and plantations.

A biooxidação do limoneno por uma linhagem de Aspergillus resulta na produção de álcool perílico e ácidos graxos de cadeia curta. A adição de quetoconazol, um conhecido inibidor da citocromo P450 oxidase, elimina a produção de ácidos graxos livres, mas não afeta a biotransformação a álcool perilhílico.

The biooxidation of limonene by an Aspergillus strain resulted in the production of perillyl alcohol and short chain fatty acids. Addition of ketoconazole, a known inhibitor of cytochrome P450 oxydase, eliminated the production of free acids, but did not affect biotransformation to perillyl alcohol.

É descrita uma síntese eficiente de um aduto de Diels-Alder da tetrametilpurpurogalina (TMPG) e o nitrosobenzeno (NOB). A cinética da decomposição térmica do aduto, que segue um mecanismo de retro-Diels-Alder foi estudada usando espectroscopía de ¹H-RMN.

An efficient synthesis of a Diels-Alder adduct between purpurogallin tetramethyl ether (TMPG) and nitrosobenzene (NOB) is reported. The thermal decomposition kinetics of the adduct, which follows a retro-Diels-Alder mechanism, was studied using ¹H-NMR spectroscopy.