Validation of a method for the quantification of (−)-epicatechin and procyanidin B2 in chocolates is reported. After a simple preparation of the chocolate test solution, thin-layer chromatography (TLC) on high-performance thin-layer chromatographic (HPTLC) cellulose plates with n-propanol-water-acetic acid (20:80:1, ν/ν) and derivatization with 4-dimethylaminocinnamaldehyde (DMACA) were performed. Densitometry at 655 nm enabled accurate quantification of both analytes in chocolates. The milk chocolate sample which served for precision and recovery experiments contained 13.0 mg/100 g of (−)-epicatechin (relative standard deviation (RSD)) 5.8%, n = 6) and 13.2 mg/100 g of procyanidin B2 (RSD 4.2%, n = 6). Usable polynomial curves were 2–30 ng for (−)-epicatechin and 4–60 ng for procyanidin B2. The validated TLC method can be applied for routine quality control of the two major polyphenolic compounds in different chocolate samples.
T. Kurosawa, F. Itoh, A. Nozaki, Y. Nakano, S.-i. Katsuda, N. Osakabe, H. Tsubone, K. Kondo, H. Itakura, Atherosclerosis 179 (2005) 237–246.