M. Al Azzam, Khaldun, et al. “HPLC Determination of Formaldehyde in Flour Samples Using 2,4,6-Trichlorophenyl Hydrazine As Derivatization Reagent”. Asian Journal of Chemistry, vol. 33, no. 4, Mar. 2021, pp. 930-6, doi:10.14233/ajchem.2021.23120.