Klaus Schwadorf

Natural occurrence of Fusarium toxins in oats harvested during five years in an area of southwest Germany

A total of 56, 56, 54, 51, and 55 oats samples used for feed production were collected randomly after the 1987, 1989, 1990, 1991 and 1992 crops, respectively, from farms located in an area of southwest Germany. Deoxynivalenol (DON), 3- and 15-acetyl-deoxynivalenol (3-, 15-ADON), nivalenol (NIV), fusarenon-X (FUS-X), T-2 toxin (T-2), HT-2 toxin (HT-2) and diacetoxyscirpenol (DAS) were determined by gas chromatography with mass selective detection (GC-MS), zearalenone (ZEA), alpha and beta-zearalenol (alpha-, beta-ZOL) by GC-MS or by HPLC. DON was the major toxin with incidences at 49-85% and mean levels in positive samples of 52-302 micrograms/kg. Incidences of ZEA, 3-ADON, NIV, HT-2, and T-2 were at 20-37, 0-30, 18-67, 0-29, and 27-61%, respectively, with mean levels in positive samples at 8-25, 5-63, 11-192, 205-296, and 20-244 micrograms/kg, respectively. alpha- and beta-ZOL and DAS were not detected in any sample. 15-ADON and FUS-X were assayed in samples from 1987, 1991 and 1992. 15-ADON was detected in 9, 4 and 0% of samples, with an average of 9 and 18 micrograms/kg, respectively; FUS-X was not detected. The incidence and levels of toxins varied from year to year. The correlation between the occurrence of toxins and precipitation is discussed.

Natural occurrence of Fusarium toxins in barley harvested during five years in an area of southwest Germany.

A total of 44, 40, 47, 51, and 58 barley samples for feed use were collected randomly after the 1987, 1989, 1990, 1991, and 1992 crops, respectively, from farms located in an area of southwest Germany. The sum of precipitation from May to September was high in 1987 and markedly lower in 1989–1992. Deoxynivalenol, 3-. and 15-acetyldeoxynivalenol, nivalenol, fusarenon-X, T-2 toxin, HT-2 toxin and diacetxyscirpenol were determined by gas chromatography with mass selective detection (GC-MS), zearalenone,α- and β-zearalenol by GC-MS or by HPLC. Deoxynivalenol was the major toxin with incidences at 71–98% and mean contents at 42–400 µg/kg. In contrast, incidences of zearalenone, 3-acetyldeoxynivalenol, nivalenol, HT-2 toxin, and T-2 toxin were at 7–68, 7–48, 11–41, 0–9, and 2–29%, respectively; with mean contents at 3–146 µg/kg. α- and β-zearalenol and diacetoxyscirpenol were not detected in any sample. 15-acetyldeoxynivalenol and fusarenon-X were assayed in samples from 1987, 1991 and 1992. 15-acetyldeoxynivalenol was detected in 30, 0 and 2% of samples, respectively, with an average content of positive samples at 8 and 4 µg/kg, fusarenon-X was not detected. Over the years, incidences and levels of toxins remained constant, decreased or increased. The correlation between the occurrence of toxins and level of precipitation is discussed.

A survey of the natural occurrence ofFusarium toxins in wheat grown ina southwestern area of Germany

Wheat for feed use (84 samples) was collected after harvest from 79 farms in a southwestern part of Germany (Baden-Wuerttemberg). The 1987 crop year was characterized by heavy rainfall in the summer months. The internal mycoflora of wheat samples was primarily fusaria, and storage fungi were rarely present. TheFusarium toxins, zearalenone (ZON), α- and β-zearalenol (α,β-ZOL), deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-AcDON), nivalenol (NIV), T-2 Toxin (T-2), HT-2 toxin (HT-2) and diacetoxyscirpenol (DAS) were analysed by gas chromatography with mass selective detection (detection limit: 1–3 µg/kg). Each of the samples contained at least one of theFusarium toxins examined except DAS. DON, ZON, 3-AcDON, NIV, T-2, HT-2 and α-ZOL were detected in 96%, 80%, 59%, 26%, 26%, 7% and 5% of samples, with an average of 1632, 178, 7, 9, 82, 10 and 23 µg/kg, and a maximum of 20538, 8036, 18, 32, 249, 20 and 71 µg/kg, respectively. β-ZOL (12 µg/kg) was found in one sample with α-ZOL (71 µg/kg). One, two, three, four, five and sixFusarium toxins were detected in 6%, 27%, 37%, 23%, 4%, and 4% of total samples, respectively. The most frequent combination was that of ZON with DON and 3-AcDON, followed by the combinations ZON/DON and ZON/DON/3-AcDON/NIV in 22, 20, and 11% of total samples, respectively.

Further survey of the occurrence of fusarium toxins in wheat grown in southwest Germany

A total of 53, 54, 57, 52 and 60 wheat samples for feed use were collected randomly after the 1989, 1990, 1991, 1992 and 1993 crops, respectively, from farms in an area of southwest Germany. Deoxynivalenol (DON), 3‐ and 15‐acetyldeoxynivalenol (3‐, 15‐ADON), nivalenol (NIV), HT‐2 toxin (HT‐2), T‐2 toxin (T‐2), diacetoxyscirpenol (DAS), and fusarenon‐X (FUS‐X) were determined by gas chromatography, combined with mass selective detection (GC‐MS), zearalenone (ZEA), α‐ and β‐zearalenol (α‐ß‐ZOL) were determined by HPLC. DON was the major toxin, with incidences at 77 to 93% and mean contents at 167 to 735 μg/kg. In contrast, incidences of ZEA, 3‐ADON, NIV, HT‐2, and T‐2 were at 13 to 37%, 10 to 44%, 15 to 67%, 0 to 11%, and 0 to 12%, respectively, with mean contents in positive samples between 2 and 73 μg/kg, except for 948 μg/kg 3‐ADON in samples from 1993. 15‐ADON and FUS‐X were assayed in samples from 1991, 1992 and 1993. 15‐ADON was found in 0 to 11% of samples at mean levels ≤ 17 μ/kg, DAS, α‐ and β‐ZOL, and FUS‐X were not detected in any sample. Over the years, incidences and levels of toxins remained constant, decreased or increased, with most differences between years being slight and insignificant. The risk for livestock due to DON, HT‐2 and ZEA was estimated based on maximum tolerated levels recommended for these toxins in some countries.

Analysis of pesticides in surface water in remote areas in Vietnam: Coping with matrix effects and test of long-term storage stability

During the last years, the increased use of pesticides and growing awareness of associated environmental and health problems have led to the implementation of various monitoring programmes in South-East Asia. The introduction of numerous new active ingredients and commercial pesticide formulations in connection with reports on pesticide-related health problems strongly indicate that the analytical procedures should be tested and evaluated for currently used pesticides. Coping with matrix effects and ensuring pesticide stability when samples are taken in remote areas are paramount. In the present study, we tested an analytical method that targets nine currently used pesticides in surface water in northern Vietnam. The method consists of solid phase extraction, storage at −18°C in the adsorbed state, and capillary gas chromatography with nitrogen-phosphorus-detection of five insecticides (dichlorvos, fenobucarb, dimethoate, fenitrothion, and chlorpyrifos), three fungicides (chlorothalonil, metalaxyl, and edifenphos) and one herbicide (atrazine). We evaluated the potential analytical bias caused by matrix effect and investigated its possible causes. We also tested the long-term stability (up to 9 months) of pesticides adsorbed to Carbopack SPE cartridges when stored at temperatures below −18°C. Adopting a matrix-matched calibration technique considerably improved the recovery values of seven of the nine tested pesticides. At spiking levels of 0.1 µg L−1 and 1 µg L−1 and after storage of 119 days at −18°C, recovery values of these pesticides ranged from 67% to 107% and from 67% to 155%, respectively. For the remaining two pesticides recovered at 53–55% at both spiking levels – dichlorvos and chlorothalonil – the method could still be useful for semi-quantitative analysis or as a screening tool. Even though the general recommendation is to minimise storage time to reduce pesticides degradation, our results showed that storage times up to nine months can be adopted for atrazine, metalaxyl, fenitrothion, and chlorpyrifos.