3.1.3. Yellows

The two yellow samples from the Paracas mummy fragments showed all of the hydroxybenzoic acid compounds that Zhang et al. [5] describe as characteristic of degradation products of the flavonoids quercetin, isorhamnetin, and kaempferol. While signals at *m/z* values consistent with the presence of a number of different flavonoids were observed in the Cave #5 mummy sample (Table 4), none were consistent across the various mass spectrometry methods, and none were unambiguously identifiable by HPLC. While two of the peaks in the HPLC had retention times consistent with the benzoisoquinoline alkaloids of *Bocconia*, their signal intensities were too low to yield a good spectral match. As the positive ion DART-MS did not show any signal for sanguinarine or chelerythrine, the most likely source of the yellow color is a degraded flavonoid. The gold sample from the loose threads associated with the turban in bundle 382-54 (02846) appears to be most similar to a degraded yellow obtained from *Bidens* or another Asteraceae, as indicated by signals at *m/z* values consistent with okanin ([M-H]− at *m/z* 287.06) and butein ([M-H]− at *m/z* 271.06) by negative ion DART-MS. For the reference samples, only those of Asteraceae (e.g., *Bidens*, *Coreopsis*, *Dahlia*) showed significant signals at these *m/z* values. This was confirmed by the HPLC results, which showed significant overlap in the pattern of compounds absorbing at 375 nm in the *Bidens andicola* sample from the Peruvian dye reference materials, as shown in Figure 1. Reference standards of butein and okanin were used to confirm the identities of the peaks at 7.7 min and 8.6 min, respectively.

Zhang et al. [5] described the difficulties of identifying chalcone colorants and how they may have been missed in earlier analyses where strong acid extraction protocols were used for HPLC analyses. Comparison of methods where the sample preparation differs is difficult at best. The DART mass spectra for the yellow dyes in the Wari textile samples from the Carlos collections showed primarily the degradation products of flavonoid yellows and little or nothing else. The HPLC results, in some cases, showed peaks at retention times different from that of luteolin, yet with markedly similar spectra, as was described by Wouters and Rosario-Chirinos in their extensive study of ancient Peruvian textile dyes [6]. The yellows from the Wari discontinuous warp and weft textiles were not consistent within the textiles, either due to variations in how they were prepared, degradation, or limitations of the methods to detect such low concentrations of chromophores. It is likely that pale undyed fibers were used to achieve the pale or off-white color observed. This seems to be the case for the cream, white, and beige samples from the one Lambayeque textile investigated, as well, which showed only traces of the hydroxybenzoic acids, some contamination from carminic acid, and no compounds specific to yellow colorants.

**Figure 1.** (**a**) Chromatograms (at 375 nm) for the gold embroidery thread from Paracas turban 382-54 02896 (black) and the reference sample of *Bidens andicola* (gray). The peak at 7.8 min was identified with a standard as okanin, and the peak at 8.6 min is consistent with butein (see Supplementary Figure S18 for spectra). (**b**,**c**) DART mass spectra for a few fibers of yarn from the same sample (**b**) and the reference sample of *Bidens andicola* (**c**)*,* both treated with formic acid prior to introduction into the ion source. The spectra clearly show [M-H]− ions consistent with those of butein, okanin, and another aglycone, maritimetin. Sulfuretin is also present in the reference dye sample.
