RESUMEN

The lack of reliable, certified calibrant solutions for the Fusarium mycotoxins deoxynivalenol (DON), 3-acetyl-DON (3-Ac-DON), 15-acetyl-DON (15-Ac-DON) and nivalenol (NIV) is a serious drawback in the already problematic area of trichothecene analysis. For this reason, purified DON, 3-Ac-DON, 15-Ac-DON and NIV standards were processed, the conditions required for their isolation and purification were optimised, and the crystalline toxins were thoroughly characterised. Several complimentary analytical methods were used to evaluate the identities of the mycotoxins and the types and amounts of impurities; results obtained from 1H and 13C NMR spectra, as well as from IR-spectra, were in agreement with the literature. Elemental analysis revealed that the isolated NIV occurs as monohydrate. If this is not known it results in a weighing error of approximately 5%. Differential scanning calorimetry (DSC) was only successful for 15-Ac-DON, as the other trichothecenes decomposed during measurements. No traces of chloride, nitrate and sulphate were found by means of ion chromatography (IC). As expected UV absorption spectra for DON, NIV, 3-Ac-DON and 15-Ac-DON yielded lambda(max) values of 216, 217, 217 and 219 nm, respectively. Minor peaks due to impurities were observed by high performance liquid chromatography (HPLC) with UV detection. The main impurity peak in the DON sample was identified by LC-tandem mass spectroscopy (LC-MS/MS) as 4,7-dideoxy-NIV (7-deoxy-DON), which occurs at levels of approximately 1.4%. Gas chromatography (GC) was performed, coupled with either an electron capture detector (ECD), a flame ionisation detector (FID), or a mass spectrometric detector (MS); however, derivatisation prior to GC analysis makes the estimation of impurities difficult. LC-MS/MS was found to be unsuitable for quantifying levels of impurities. It can be concluded that high-purity (>97%) B-trichothecene standards were successfully processed and fully characterised for the first time.

Asunto(s)

RESUMEN

A new method for the determination of zearalenone in edible oils with size exclusion chromatography (SEC) followed by LC-MS/MS as well as HPLC-FLD was developed and validated. By using the LC-MS/MS determination no further clean up step is necessary after the SEC. The correlation coefficient of 0.999 for the two detection systems is acceptable. In this research 77 edible oils were analyzed. The mean average value of 38 corn germ oils was 169 µg/kg, the maximum value amounted up to 921 µg/kg.

RESUMEN

The research project "Methods of Analysis and occurrence of important Fusarium toxins (deoxynivalenol and zearalenone) as well as the intake of these toxins by the German consumer" supported by the Federal Ministry of Consumer Protection, Food and Agriculture (BMVEL) is processed by the institutions mentioned above. This work represents a comprehensive summary of the contamination of food by zearalenone (ZEA).

RESUMEN

Within a joint research project entitled "Analysis and occurrence of importantFusarium toxins (deoxynivalenol and zearalenone) and dietary intake of these toxins by the German consumer", supported by the German Federal Ministry of Consumer Protection, Food and Agriculture (BMVEL), representative analytical data are generated on the contamination level of foods withFusarium mycotoxins. This paper gives a comprehensive summary concerning the contamination of foods from the German market with deoxynivalenol (DON) in the period from August 2001 to April 2004. More than 4700 food samples (mostly cereals and cereal-containing foods) were purchased from food shops in Germany and analysed for DON by enzyme immunoassay, HPLC, and LC-MS/MS, respectively. All analytical methods were validated through intra- and interlaboratory studies and gave mean recoveries of >80% for each matrix. Although DON was detected with high frequency in all cerealcontaining samples, the mean and median levels were in most products well below the recently established maximum permitted limits in Germany.

RESUMEN

DON is the only mycotoxin of the trichothecene group that has been regulated in food so far by the German authorities. The quantitative determination of DON in food and feed therefore is of great importance regarding compliance with legal limits. An important source of measurement error is the bias introduced by different absolute concentration of calibration standards. To make an estimation of the contribution of calibration standards to total error six different DON-standards provided by the participants of the project "Analysis and occurence of important Fusarium toxins (DON and ZEA) and uptake of these toxins by the German consumer" sponsored by the German Ministry of Consumer Protection, Nutrition and Agriculture (BMVEL, Projekt BLE 00HS055) were analyzed and compared to three batches of commercial standard solutions. The range of the results was between 29.2 and 26.3% for the laboratory standards and 11.3 respective 3% for the commercial standards depending on different calculation modes (UV height and area and fluorescence height). Therefore a substantial reduction of the measurement error by using commercial standards instead of laboratory-prepared standards seems possible.

RESUMEN

An enzyme-linked immunoassay (ELISA) was used for screening atrazine residues in soil. Samples were annually collected in Southern Germany between 1993 and 1998. An average of 419.5 samples was analyzed per year amounting to 2517 samples. The fraction of positive samples defined by atrazine concentrations >100 microg/kg soil decreased successively from 8% (corresponding to 33 samples) in 1993 to 0.6% (corresponding to 2 samples) in 1998. All positive samples and a selection of negative samples were subsequently validated by HPLC. Comparison of ELISA and HPLC data yielded correlation coefficient values of r = 0.958-0.981 (n = 18-47), except for 1995 when only a correlation of r = 0.864 (n = 18) was obtained. Four samples were overestimated and another 4 were underestimated with respect to the atrazine threshold value of 100 microg/kg soil as revealed by HPLC validation. Thus, 99.68% of 2,517 analyzed samples were correctly evaluated. The precision and reproducibility of the ELISA were adequate for a prescreening tool. The low cost per sample and the high sample throughput are not yet achievable by conventional analytical methods. The described combination of ELISA and HPLC has the potential to take advantage of both methods and to restrict determination errors to a minimum.

Asunto(s)

RESUMEN

In the course of a Fusarium Monitoring for winter wheat in Bavaria five deoxynivalenol risk factors have been identified. The major Fusarium species wasF. graminearum, which usually has one disease cycle; under specific weather conditions obviously a bicyclic spread of the pathogen occurs.

RESUMEN

Samples of wheat (n = 25) and maize (n = 30) for animal consumption, collected in 1997 after harvest from western Romania, were analyzed by enzyme immunoassays for mycotoxin contamination. Toxins analyses included deoxynivalenol (DON), 3-acetylDON, 15- acetylDON, fusarenone X (FX), T-2 Toxin (T-2), diacetoxyscirpenol (DAS), zearalenone (ZEA), fumonisin B(1) (FB(1)), aflatoxin B(1) (AFB(1)), ochratoxin A (OA), and citrinin (CT). DON and acetylDONs were the major contaminants in wheat (100%) and maize (46%). Median values for DON, 3-acetylDON, and 15-acetylDON were 880 microg kg(-1), 66 microg kg(-1), and 150 microg kg(-1) in wheat, and 890 microg kg(-1), 180 microg kg(-1), and 620 microg kg(-1) in maize, respectively. Additionally, 3,15-diacetylDON was detected in some samples by HPLC-EIA analysis. All samples were negative for FX (<150 microg kg(-1)). T-2 was found in wheat (n = 6) and maize (n = 1) at levels between 13 and 63 microg kg(-1). DAS (2.6 microg kg(-1)) was found in one maize sample. ZEA occurred in all wheat and in four maize samples, median values were 10 microg kg(-1) and 250 microg kg(-1), respectively. One maize sample contained FB(1) (140 microg kg(-1)). All samples were AFB(1)-negative (<4 microg kg(-1)). OA was found in one wheat sample (37 microg kg(-1)), CT was found in one maize sample (580 microg kg(-1)). This first reported natural occurrence of a range of mycotoxins in Romanian feeding stuff shows that DON and acetyl DONs may be present at levels which may affect animal production.

RESUMEN

Several semisynthetic liquid media were examined for the large-scale production of deoxynivalenol (DON) und 3-acetyldeoxynivalenol (AcDON) by Fusarium graminearum 183. Only in three of the eight media used could high toxin yields of DON and AcDON be detected. The maximum levels of DON in a medium according to Miller were 3 mg/l and of AcDON 32 mg/l. In glucose-yeast extract-peptone (GYEP) medium containing 1% glucose, the AcDON concentrations reached 33 mg/l and the DON yields were 19 mg/l. In a rice flour liquid medium, however, the mean levels of AcDON and DON increased to 170 mg/l and 9 mg/l, respectively. The maximum amounts observed were 480 mg/l for AcDON and 65 mg/l for DON. The addition of trifluoracetic acid sodium salt or malonic acid, which are suggested to cause an accumulation of acetyl-CoA by inhibiting enzymes of the tricarboxylic acid cycle, did not stimulate the toxin formation.

Asunto(s)