Qualitative analysis of Sudan IV in edible palm oil Sampson Saj Andoh, Tarmo Nuutinen, Cheetham Mingle and Matthieu Roussey J. Eur. Opt. Soc.-Rapid Publ., 15 1 (2019) 21 Published online: 11 September 2019 DOI: 10.1186/s41476-019-0117-0