Simultaneous Analysis of the Coloring Compounds in Indigo, Phellodendron bark, and Madder Dye Using HPLC-DAD-MS

Abstract

Indigotin, indirubin, berberine, palmatine, alizarin, and purpurin are major pigments of indigo plant, Phellodendron bark, and madder. The six pigments were examined using the HPLC-DAD-MS instrument for the purpose of the simultaneous detection of the pigments in a single sample run. The HPLC-DAD-MS method examined the individual pigment solutions in DMSO, a solution containing 6 pigments, and the DMSO extract of the silk dyed with a dye solution of 5 pigments excluding indirubin. The retention times of the HPLC chromatograms, λmax of the uv-vis absorption bands in the DAD analyses, and the molecular ions detected for the compound peaks in the MSD analyses were consistent throughout the analyses of individual pigment solutions, mixed pigment solutions, and dye extracted from silk dyeing. The developed instrumental method of the simultaneous detection of six pigments can identify dye in an exhumed textile if the textile is dyed using any one (or multiple) pigments of indigo, Phellodendron bark, or madder plant.

Thermal degradation of natural dyes and their analysis using HPLC-DAD-MS

“…The retention times of the peaks of berberine (1), palmatine (2), alizarin (3), purpurin (4), indigotin (5), and indirubin (6) the λ max of both compounds appeared in the UV absorption band of each compound concomitantly (Figure 2). However the two compounds were distinguishable using the differences in major molecular ion typical of each compound which were m/z 263 for indigotin and m/z 257 for purpurin (Ahn et al, 2013;Ahn et al, 2014;Ren et al, 2007). The chromatogram peaks of berberine and palmatine also overlapped and their UV absorption bands were identical due to the fact that berberine and palmatine were both protoberberine alkaloids (Ahn et al, 2013;Ahn et al, 2014;Zhang et al, 2009).…”

“…However the two compounds were distinguishable using the differences in major molecular ion typical of each compound which were m/z 263 for indigotin and m/z 257 for purpurin (Ahn et al, 2013;Ahn et al, 2014;Ren et al, 2007). The chromatogram peaks of berberine and palmatine also overlapped and their UV absorption bands were identical due to the fact that berberine and palmatine were both protoberberine alkaloids (Ahn et al, 2013;Ahn et al, 2014;Zhang et al, 2009). But the two compounds were distinguishable by the major molecular ions [M + H 2 ] + of each coloring compound which are m/z 338 and m/z 354 respectively Ren et al, 2007).…”

“…Six standard dyes were dissolved together in 300 mL DMSO with concentrations 0.016 g/L for indigotin and indirubin, 0.033 g/L for berberine, palmatine, alizarin, and purpurin to make a standard mixed dye solution, following Ahn et al (2013).…”

“…First, a mixed dye solution containing 0.025 g each of berberine, palmatine, alizarin, and purpurin was made in 370 mL of purified water, following Ahn et al (2013). Approximately 2.45 g of silk fabric sample was mordanted with 0.49 g of aluminium potassium sulfate for 1 hour at 60°C (referred to as alum-mordanted silk in the following).…”

“…Approximately 0.5 cm × 0.5 cm size dyed silk specimen from each of the degraded sample was place in a small beaker with 0.4 mL of mixed solution of HCl/methanol/ water (2:1:1 v/v/v) (Ahn et al, 2013). The beaker was placed in 100°C oven for 15 min so that the liquid can completely evaporate.…”