Lea Pallaroni

Determination of zearalenone from wheat and corn by pressurized liquid extraction and liquid chromatography-electrospray mass spectrometry.

Zearalenone (ZON) was extracted from wheat and corn by using pressurized liquid extraction (PLE) and the PLE extracts were analyzed using liquid-chromatography-mass spectrometry (LC-MS) without further clean-up procedures. A statistical design approach was applied to evaluate the influence of several extraction parameters such as temperature (40 degrees C; 80 degrees C; 120 degrees C), time (5 min; 10 min) and solvent extraction mixture [acetonitrile-water (9:1, v/v); methanol-water (8:2, v/v); methanol-acetonitrile (1:1, v/v)] on fortified cereals. The results showed a strong influence of the solvent composition on recovery of ZON. Quantification of the analytes was performed by LC-MS analysis of the raw extract using matrix-matched standard curves. The method performance was tested in the selected conditions (80 degrees C; 5 min; two cycles; methanol-acetonitrile) on samples which had been previously used for an international proficiency test. Compared to the assigned value, the recovered ZON was 118% [relative standard deviation (RSD)=5.2%, n=3)] and 107% (RSD=2.2%, n=3) in wheat and corn, respectively. Therefore, PLE can be used for ZON extraction, achieving good performances and allowing for an automated handling of the sample extraction step. Successively, the influence of temperature and number of cycles was investigated on naturally contaminated corn. From these results it could be concluded that fortified experiments perfectly mimicked naturally contaminated samples.

OPTIMIZATION OF ATMOSPHERIC PRESSURE CHEMICAL IONIZATION INTERFACE PARAMETERS FOR THE SIMULTANEOUS DETERMINATION OF DEOXYNIVALENOL AND ZEARALENONE USING HPLC/MS

In this paper, the influence of several atmospheric pressure chemical ionization (APCI) parameters were investigated in flow-injection for the simultaneous determination of deoxynivalenol (DON) and zearalenone (ZON) using liquid chromatography (LC) coupled to a mass spectrometer (MS). During the optimization procedure of the APCI interface, it was revealed that vaporiser temperature and capillary temperature had a strong influence on the MS signal of DON and ZON in the positive and in the negative ionization mode. In the positive mode a higher absolute signal of both compounds was obtained, while in the negative mode a higher selectivity was achieved. Thereafter, tube lens offset, corona discharged current, and capillary voltage were investigated in the negative mode; it was shown that only the tube lens offset had a large influence on the MS signal of the analytes. Finally, the optimized conditions were confirmed injecting and separating a standard mixture on a LC column prior to MS detection.

INVESTIGATION OF ALTERNATIVE REAGENTS TO 2-MERCAPTOETHANOL FOR THE PRE-COLUMN DERIVATIZATION OF FUMONISINS WITH O-PHTHALDIALDEHYDE, FOR HPLC ANALYSIS

ABSTRACT This paper investigates the suitability of 37 reaction partners for the derivatization of fumonisins with o-phthaldialdehyde (OPA). All resulting fumonisin derivatives were compared for stability by UV-absorption. Subsequently, the relative fluorescence and retention times of derivatives found to be stable in UV-absorption were investigated by high performance liquid chromatography (HPLC), using well-established chromatographic conditions for fumonisin analysis. Several alternatives to 2-mercaptoethanol could be identified to be superior derivatization agents (3-mercapto-propionic acid, N-acetyl-cystein and thioglycerol). Those are especially valid when immunoaffinity column clean up is used prior to derivatization. The structure of the fumonisin B1-derivative obtained from the most suitable derivatization agent N-acetyl-cystein was verified by HPLC-MS.

Alternative extraction methods for Zearalenone: Microwave Assisted Extraction and Accelerated Solvent Extraction

Zearalenone (ZON) was extracted from wheat and corn by using Microwave Assisted Extraction and Accelerated Solvent Extraction. A factorial design approach was applied to evaluate the influence of the most important extraction parameters such as temperature, time and solvent extraction mixture on fortified cereals. ZON was determined by LC-MS without performing any clean-up after the extraction to better evaluate the extraction efficiency. The selected extraction conditions were tested on samples which had been previously used in an international proficiency test. Applying the selected extraction conditions both alternative extraction procedure provided satisfactory results comparable to the most commonly used method.