The high cost of crude oil combined with the need for cleaner, renewable motor energy has renewed interest in the use of modified vegetable oils as diesel fuels.These oils are processed with methanol to produce fatty acid methyl ester mixtures (FAME) that is pure biodiesel.In everyday usage biodiesel is commonly mixed with petroleum diesel resulting in a hybrid blended fuel.Both the pure biodiesel and the blendedfuels present unique challenges when measuring product purity.This paper will offer an overview of standard biodiesel G-C methods for the analysis of key contaminants in pure biodiesel and FAME content in blends.Improvements and alternative GC method will be presented that use gas phase microfluidics and 2-D GC.These new approaches improve the ease and precision of routine biodiesel analysis.