Two methods for the determination of Sudan dyes (Sudan I, Sudan II, Sudan III and Sudan IV) in food samples, by solid phase extraction - capillary liquid chromatography, are proposed. Both methods use nanocellulose (NC) extracted from bleached argan press cake (APC), as a nano-adsorbent recycled from an agricultural waste material. One of the methods involves the dispersion of NC in food sample extracts, along with the waste and eluents being separated by centrifugation. In the other method, NC was modified by magnetic iron nanoparticles before using it in the extraction of Sudan dyes. The use of a magnetic component in the extraction process allows magnetic separation to replace the centrifugation step in a convenient and economical way. The two proposed methods allows the determination of Sudan dye amounts at the 0.25–2.00 µg L−1 concentration range. The limit of detections, limit of quantifications and standard deviations achieved were lower than 0.1 µg L−1, 0.20 µg L−1 and 3.46% respectively, when using NC as a nano-adsorbent, and lower than 0.07 µg L−1, 0.23 µg L−1 and 2.62%, respectively, with the magnetic nanocellulose (MNC) was used. Both methods were applied to the determination of Sudan dyes in barbeque and ketchup sauce samples, obtaining recoveries between 93.4% and 109.6%. © 2017 Elsevier B.V.