First dry and mill your samples. Then extract the lipids and chlorophyll with acetone and then ether in the fume hood. After drying the organic solvents you should be able to follow K-TSTA procedure. Please record loss on drying and extraction so you will be able to correct the final starch content for moisture and fat removed.
It is possible to check for interference by adding an internal standard (glucose) to your sample, quantitative recovery of this standard would be expected so that you can rule out interference.