Addition of ammonia to final concentration 2% inactivates ochratoxin A, aflatoxin, citrinin, penicillic acid and partially zearalenon at temperature 20-50 degrees C. Detoxification of contaminated cereal grain (wheat, corn or barley) can be performed on a farm using ammoniation without special investment during 4 to 6 weeks. Ammoniation changes nutritional value of grain as feed in a small extent.

Kernels of several varieties of wheat, rye and barley were found to have different resistance to fungi attack and ochratoxin A production, particularly in first step of fungus development on kernels. Zinc was stated to be a limiting factor of ochratoxin production. viable sound kernels were very resistant against fungi. Dead (e.g. autoclaved) kernels were attacked by fungus very quickly. Varieties with stronger resistance to fungi invasion during storage were selected.

Ammoniation was proved to be a suitable detoxification procedure to remove toxicity of Aspergillus ochraceus mycotoxins (mainly ochratoxin A) from contaminated cereal grain (corn, wheat and barley). It was found that ammoniation should be performed to achieve decomposition of ochratoxin A to nondetectable level. Ammoniated grain can be used as feedstuff component without essential change of nutritive value during ammoniation.

The fluorescence micromethod of aflatoxins B,, B,, G, and G, determination in solution is described. The amount about 0.1 kg of aflatoxins B, and GI, and 0'01 pg of aflatoxins B, and G, in one spot after elution with methanol can be determined, with accuracy about 5%. The results of described fluorescence method are in agreement with results of spectrophotometric, fluorodensitometric and visual determinations. A very strong influence of light on results of aflatoxins B, and G, determination was stated. Photodecomposition of aflatoxins B, and G, to several photoproducts was observed.In our previous paper [I] we described the occurrence of aflatoxins ingrain crops and other products, their biological effect, methods of determination and detoxification.The methods of determination of aflatoxins are based mainly on their ability to light absorption and fluorescence emission. The quantitative analysis by fluorescence method can be effected by visual evaluation directly on the chromatoplates, or fluorodensitometrically. Because of its subjectivity the first method gives inaccurate results. The second requires an expensive and complex equipment including a self-recording fluorodensitometer and an integrator enabling the calculation of concentration of individual aflatoxins from the surface of cones. A good separation of spots is required besides. This is why an attempt was made to apply the measurements of fluorescence after the elution of spots from the silica gel with methanol [2].

The simple method for determination of small amounts of aflatoxins (about 5 -10 yg/kg) was described. The method was adopted for wheat, barley, rye and oats. Difficulties of aflatoxins determination in cereals are discussed, mainly observed during purification of extracts and resolution by TLC. Different tests were compared for confirmation of aflatoxins in cereals.Results of cereal crops control for contamination with aflatoxins are presented.The differences between results obtained in collaborative studies on the determination of aflatoxin in corn are very considerable, especially for samples of corn with content of toxins lower than IOO Fg per kg [IS, 211. Standards admitted by WHO, on contents of aflatoxins of about 10 yg per kg request the elaboration of considerably more sensitive methods. The detection as well as the precise determination of such small amounts of aflatoxins in a sample creates additionally analytical difficulties. In the greater part of products contaminated by aflatoxins there is a considerable amount of impurities which make impossible their determination without a previous thorough removal of the impurities from the extract [I, 4, 6 , 8-10, 12, 13, 15, 16, 20, 221.As it appears from literature information and from our own experience the reasons for the diversified results in the quantitative determination of aflatoxins by chromatographic methods can be listed as follows:I. Distribution of aflatoxins material is often not uniform. Such a distribution causes considerable differences in the results of parallel average samples. 2. Losses during the extraction caused by the use of improper solvents for instance in methanol by decomposition under influence of light, etc. 3. Losses during the purification on chromatographic columns. 4. Improper resolution on thin-layer chromatograms.5. Decomposition on chromatograms especially under the influence of light.6. Masking the fluorescence of aflatoxins spots by impurities which fluoresce or quench the fluorescence, especially in grain extracts.Our investigations have confirmed these observation;, because in each stage we have stated losses of aflatoxins. For this reason we have controlled on each stage (extraction, purification, TLC resolution and fluorodensitometry) in order to find out the causes of the losses.We also investigated the possibility of a most simple method elaboration for aflatoxin control in grain crops.