A simple TLC method for the determination of pro-vitamin A content of fruits and vegetables.

A simple and rapid method to isolate and estimate carotene compositions of tomatoes, carrots and green vegetables is described. The chief distinguishing features of this method are its simplicity in the preparation of TLC plates that avoids the requirements of the TLC applicator, and avoiding the meticulous conditions like saturation of chamber etc. employed in the routine TLC methods. By employing this method carotene compositions of tomatoes, carrots and the green vegetable, Amaranthus gangetica are determined. The time taken for the separation of various carotene bands of several samples is as short as 10 minutes. As many as 20 different samples could be analyzed at a time. The values obtained for the individual carotenoids by this TLC method are in very good agreement with those obtained after the column chromatographic separation of the same material. Saponification is not required for the extracts from tomatoes and carrots as it does not influence the individual values of carotenes. Hence in these cases, crude extracts can be directly analyzed by TLC. However, in case of the green vegetables (Amaranthus gangetica, for example) the value of beta-carotene after saponification was found to be twice the value obtained by TLC of the crude extract as such. The general applicability of this method in the separation of vitamin A alcohol from its esters, retinoic acid from retinoic acid anhydride etc. has been discussed. The method would be quite handy and of particular use to especially those carrying out the genetic studies with tomatoes and carrots. It could be employed for a quick and accurate determination of pro-vitamin A content of fruits and vegetables and is more economical than the standard TLC procedures.