a very simple and quick method to detect aflatoxins from grains , beans and other raw materials is direct exposore to ultraviolets of 254-366 nm. A bluish or greenish fluorescence allow you to have a general orientation about a possible contamination.
First,you please try to isolate Aspergillus flavus,the most common mould that produces aflatoxin. Please remember that all isolates/strains of A.flavus are not toxigenic.You can use simple media such as Sabouraud agar,Pal sunflower seed or cocconut agar to grow A.flavus from feed or food.Later,you can expose the culture to UV light and see the colour .This is the most simple way to know the presence of aflatoxin in the world, which can be done without much expenditure even by poor resource countries.The sophisticated techniques such as ELISA,chromatography etc are not easily available every where.I always used very simple and cheap methods to work on medically important fungi.By the blessing of God,I could publish over 415 papers mostly of mycology,and authored on textbook entitled on "Veterinary and Medical Mycology",published in 2007 by Indian Council of agricultural Research,New Delhi,India.If you have this book in your library, you can know about many simple media and stains ( some of these such as PHOL stain and Narayan stain developed my us) .Mycology is a very growing area of biological science but the researcher must keep the patience as some of the fungi are slow grower and require 4 to 6 weeks time.I am very sure that you can do wonderful work in the field of mycology.I have uploaded many papers on research Gate and Academia.You can read my papers on Medical and Veterinary Mycology.I have not done any research work on mycotoxicoses.I am now 70 years old but still contributing in the field of Mycology and Public Health
There're some simple test kits for screening analysis of aflatoxin using the ELISA concept. For example, one test kit is a competitive direct ELISA that provides a visible screening result against a known control toxin concentration. Free toxin in the sample and control competes with enzyme-labeled toxin (conjugate) for the antibody binding sites. After a wash step, substrate reacts with the bound enzyme conjugate to produce blue color. If the sample has less blue color than the control, it contains more toxin than the control. For more info.
ELISA though is a simple technique but it is not easily available in every laboratory.If the country is rich,one can use any of the latest techniques.I always think for the poor resource countries, which even do not have even facilities for Gram and acid fast techniques.I have seen that even potassium hydroxide is also not available to do direct microscopy of the skin scrapings to confirm the presence of dermatophytes.