Fig 1.
Products of eumelanin and pheomelanin generated by alkaline oxidation.
Fig 2.
Characterization of the melanin oxidation products PDCA, TDCA, PTCA and TTCA from brown chicken feather by mass spectra (negative ion mode) and UV spectra.
Fig 3.
Comparison of extracted ion chromatograms.
(a) and corresponding UV chromatogram (b) of oxidation products from a brown chicken feather following SPE, highlighting the need for peak confirmation in biological samples.
Table 1.
Accurate mass data of melanin oxidation products.
Table 2.
Limit of detection (LOD), limit of quantitation (LOQ) and linearity (R2) for HPLC with UV detection.
Table 3.
Effect of biological matrices on the recovery of melanin oxidation products following SPE.
Fig 4.
Extracted ion chromatograms of melanin oxidation product standards and melanin reference compounds (standard mixture of oxidation products, synthetic eumelanin, Sepia ink melanin) as well as biological samples (human hair, chicken feather, bivalve shell) following alkaline oxidation.
Table 4.
Amounts of melanin oxidation products in melanin standards and biological samples per g of oxidised starting material as quantified by HPLC with UV detection.