Diglycerides and monoglycerides are by-products of biodiesel production and are also considered contaminants in the final product. For now, USA and EU standards set limits on the permissible levels of bound glycerol. In this study, a simple and reliable method (TLC-FID) has been developed to determine hydrocarbons, fatty acid methyl esters, free fatty acid, triglycerides, diglycerides and monoglycerides, and polar lipids in biodiesel and biodiesel blends. Analysis was accomplished on an IATROSCAN MK-6s system using silica gel rods. The biodiesel samples were applied to thin rods of silica gel which was then separated in typical TLC procedures. The effects of various operational parameters such as developing solvent systems and TLC-FID chromarod mass loading were systematically studied. The TLC-FID chromatograms have been standardized through the selection and identification of reference peaks and the normalization of retention times and peak intensities of all the common peaks. Partially transmethylated soybean oil, Chlorella pyrenoidosa oil, Spirulina oil and B10 have been used as case studies to illustrate the optimization procedure and the application of the technique. The optimized TLC-FID method shows high stability and reproducibility, and thus can be used effectively for the screening analysis or quality assessment of biodiesel or biodiesel blends. (C) 2013 Elsevier Ltd. All rights reserved.