DMACA reagent

Fig. 3.5 Standard curves of epicatechin and cyanidin-3-O-gfucoside with DMACA reagent...

In the past few years considerable attention has also been given to the use of the DMACA reagent as a histochemical stain in the analysis of procyanidin containing cells [67,153] and as a post-column derivatization reagent in HPLC analysis of procyanidins (see section chromatography) [151,154],... 

The use of dimethylaminocinnamaldehyde (DMACA) as a reagent for the colorimetric determination of flavanols was first described by Thies and Fischer [146]. The first protocol was developed by Me Murrough and Me Dowell [147] for purified extracts of barley and hops (Humulus lupulus). The reaction scheme is the same as for the vanillin reaction. The reactivity of proanthocyanidins essentially again resides in the 5,7-hydroxylation of the aromatic A-ring, a single bond between C2 and C3 and the lack of a... 

Catechin is generally used as a standard in the DMACA assay. Calibration plots are linear and therefore, calibration factors are also applied [148]. Like in all conventional methods the use of purified procyanidins as a standard will give the correctest estimates. A blank, composed of the samples without the chromogen reagent, is also... 

FIGURE 17.6 Mass spectra of procyanidin B2 (a) and (—)-epicatechin (b) obtained from chocolate sample test solntion after elution of zones from the HPTLC cellulose plate developed in water. Here, bands are visualized by postchromatographic derivatization with DMACA detection reagent. 

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