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11Figure 1. (A) HPLC profile “fingerprint” of an extract of pagoda tree bud dyed silk; (B) UV-visible spectrum ofthe rutin peak; (C) a mass spectrum of the same peak. The table lists information about each peak in the profileHowever, before analyzing a dye mixture, one has to remove it from the textile fibres.For many years, the conventional technique for extracting dyes was to cook the fibres withaqueous solutions of hydrochloric acid (HCl) or other strong acid. This method is effective,but it also destroys many of the dye molecules, most of which (at least in the case ofyellows) are glycosides (conjugates of a sugar and a dye molecule; see Figure 2). For example,if the pagoda tree bud dyed silk referred to in Figure 1 had been extracted with HCl, all of thepeaks (at least six components) to the left of quercetin would have disappeared. In fact, theresulting profile would have been indistinguishable from that derived from onionskins. To getaround this problem, we devised a couple of mild extraction procedures that preserve theglycoside linkages 2 . The dye components shown in Figure 1 were obtained by mildextraction.