Mostly little quantity of acids like formic and acetic acids are added during TLC to reduce tailing. You can refer the following books which are considered milestones in Chromatography, this will definitely end up ur search regarding the querry you have now:

1. Stahl E (1967). Text Book of Chromatography, 2nd Ed., Springer-Verlag, Berlin.

2. Wagner H, Baldt S. (1996). Plants Drug Analysis, Springer Verlag, Berlin Heidelberg,

3. WHO (1989). The Validation of Analytical Procedures used in the Examination of Pharmaceutical Materials, WHO/Pharm. 89541, rev 2 Genf,.

4. Harborne JB (1973). Phytochemical Screening Methods In: A Guide to Modern Techniques of Plant Analysis. 1st Edition, Chapmann and Hall, London.1973

Regards and gud luck

Thank you very much for the book's reference.