Quantitative determination of alliin in dried garlic cloves and products by high-performance thin-layer chromatography

Purpose: To standardize the garlic samples and its products for alliin contents.
Methods: A direct high-performance thin-layer chromatographic (HPTLC) method was developed to determine alliin in Chinese (CG) and Indian garlic (IG) and two other marketed products from USA and UK, respectively. Scanning and quantification were performed at 205 nm. Furthermore, chromatography was performed on pre-coated HPTLC plates with the solvent mixture, n – hexane:ethyl acetate (29:1 v/v), as the mobile phase. In addition, the parameters suggested by International Conference on Harmonization for analytical procedures were considered to validate the proposed method.
Results: The system gave a compact spot of alliin at RF = 0.19 ± 0.01 The linear regression data for the calibration plots showed a good linearity (r² = 0.996) in the concentration range of 200 - 1600 ng. Linear regression equation was represented by Y = 1.792x + 182.855, while LOD and LOQ values were 40.42 ngband^-1 and 111.72 ng.band^-1, respectively. The method showed excellent accuracy with recovery of 98.20 – 99.10 % and good precision with RSD of 1 - 2.65 %.
Conclusion: The proposed method is selective, sensitive and accurate for the determination of alliin in garlic and its products. It is also evident from the results obtained that raw Indian garlic has higher alliin content than Chinese garlic.