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Table 2 Historical samples—synthetic dye

From: Twentieth century Iranian carpets: investigation of red dye molecules and study of traditional madder dyeing techniques

Sample code Dye compounds: (M: major compound) (m: minor compound) Relative ratio of peak areas of detected spectra at 255 nm Chemical structure
A1 S1 (Rt:22.1 min) 100% S1
A2 S1 (Rt:22.1 min) 100% S1
A3 S2 (Rt:16.9 min) (M)–S1 (Rt:22.1 min) (m) 66% S2, 4% S2’, 30% S1
C1 S1 double peak (Rt:21.6 min–Rt:22.1 min) 67–33% S1–S1
C2 S1 double peak (Rt:21.6 min–Rt:22.1 min) (M)
S2 (Rt:16.9 min) (m)
12% S2, 64–24% S1–S1
D1 S2 (Rt:16.9 min) 100% S2
E1 S1 (Rt:21.5 min) 100% S1
E2 S2 (Rt:16.9 min) 100% S2
F1 S1 double peak (Rt:21.4 min–Rt:21.9 min) (M), S1’ (Rt:21–Rt:22.8 min) (m), S2 (Rt:16.9 min) (m) 4% S2, 5% S1’, 64–27% S1–S1, 1% S1’
F2 S1 double peak (Rt:21.4 min–Rt:21.9 min) (M), S1’ (Rt:21–Rt:22.8 min) (m), S2 (Rt:16.9 min) (m) 4% S2, 5% S1’, 57–30% S1–S1, 3% S1’
F3 S2 (Rt:16.9) (M), S2’ (Rt:18.6 min) (m), S1 double peak (Rt:21.4 min–Rt:21.9 min) (m), S1’ (Rt:21–Rt:22.8 min) (m) 69% S2, 6% S2’, 1% S1’, 16–8% S1–S1
F4 S2 (16.9 min) (M), S2’ (Rt:18.6 min) (m), S1 double peak (Rt:21.4 min–Rt:21.9 min) (m) 82% S2, 6% S2’, 9–2% S1–S1
G1 S1 double peak (Rt:21.4–Rt:21.9 min) 80–20% S1–S1
G2 S1 double peak (Rt:21.4–Rt:21.9 min) 74–26% S1–S1
  1. S1 absorbance spectrum maxima at 217–288–314–324–514 nm, S2 absorbance spectrum maxima at 229–310–487 nm, S1’ similar absorbance spectra as S1, S2’ similar absorbance spectra as S2, S1–S1 S1 double peak, relative ratio (%) individual peak area divided by sum of peak areas multiplied by 100