ABSTRACT
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
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.
ABSTRACT
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 â-hydroxipalmitic acid and sterified with the C12-C16 acids. All five fractions have antifungic activity at ìg/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.