Analysis of tea shoot catechins: Spectrophotometric quantitation and selective visualization on two-dimensional paper chromatograms using diazotized sulfanilamide

A highly specific and sensitive diazotized sulfanilamide reagent is synthesized for determination of tea catechins. The reagent is employed both as spray reagent for selective visualization of tea catechins on two-dimensional paper chromatograms (sensitivity <1 mu g of d-(+)-catechin) and for their spectrophotometric quantification in the crude extracts of tea polyphenols isolated from fresh or dried tea shoots. The formation of yellow color (lambda(max) = 425 nn) between catechins and diazotized sulfanilamide was investigated and made the basis of It simple and sensitive spectrophotometric method for estimation of the total and individual catechins in different tea cultivars. At 425 nm, the absorbance was Linear (r = 0.999) over the (0.4-8.0 mu g/mL) concentration range of d-(+)-catechin.