Agilent scientist John Lee recently authored an article in Food Quality & Safety Magazine about that very topic.
Tea is the third most widely consumed substance on the planet (after air and water). Technically, all “tea” is made from the same leaf – an evergreen shrub called camellia sinensis, also known as the “tea plant.” By changing the level of oxidation, you end up with white, black, green, yellow or oolong tea.
(“Herbal tea” is not actually tea. It’s made by infusing fruits or herbs, but without using actual tea leaves.)
Tea has a highly complex chemical composition that includes diverse nutrients, carbohydrates, amino acids, vitamins, lipids and volatiles. Even just the mixture of phenolic compounds in tea is so complex that it is very difficult to see all of these nutrients in one traditional liquid chromatography analysis. (LC is the technique most often used to separate and detect such compounds.)
So Agilent has developed a comprehensive analysis technique that uses two-dimensional liquid chromatography. In 2D-LC, the effluent from a first LC column is injected into a second LC column for further separation. Having two dimensions of separation greatly increases the resolving power of such analyses, but doesn’t increase the analysis time.
This 2D-LC technique successfully enabled a precise quantification of the various important alkaloids, caffeine, theobromine and catechins in tea. On top of that, scientists were also able to more fully see other differences between green and black tea.
John Lee is Agilent’s Global Food Market Manager. He resides in the UK where his preferred drink is, of course, tea. And he always makes his tea with boiling water, so as to ensure the fullest flavor!
For more information go to: