TABLE 4.

Quantitative analysis for the quality control of IN.

Analyte	Method	Results	References
Indigo	1H-NMR	1.4–2.7%	Plitzko et al. (2009)
Indigo	HPLC	1.1–1.4%	Plitzko et al. (2009)
Indirubin	HPLC	0.16–0.37%	Plitzko et al. (2009)
Indigo	HPLC	1.18–3.47%	Pan et al. (2018)
Indirubin	HPLC	0.09–0.26%	Pan et al. (2018)
Indigo	FTIR spectroscopy	1.46–2.82%	Pan et al. (2018)
Indirubin	FTIR spectroscopy	0.12–0.23%	Pan et al. (2018)
CaCO3	ICP-OES	59.125–96.175%	Pan et al. (2018)
CaCO3	FTIR spectroscopy	60.925–87.125%	Pan et al. (2018)
Indigo	HPLC	30.07%	Sun Z. et al. (2020)
Indirubin	HPLC	0.145%	Sun Z. et al. (2020)
Indigo	UPLC	13.87%	Liang et al. (2019)
Indirubin	UPLC	0.15%	Liang et al. (2019)
Indole	UPLC-APCI-TOFMS	0.0002574%	Naganuma et al. (2018)
Indole-3-aldehyde	UPLC-APCI-TOFMS	0.0000203%	Naganuma et al. (2018)
Tryptanthrin	UPLC-APCI-TOFMS	0.000124%	Naganuma et al. (2018)
Indigo	UPLC-APCI-TOFMS	0.2507%	Naganuma et al. (2018)
Indirubin	UPLC-APCI-TOFMS	0.08347%	Naganuma et al. (2018)
Betulin	UPLC-APCI-TOFMS	0.0007956%	Naganuma et al. (2018)
β-Sitosterol	UPLC-APCI-TOFMS	0.003974%	Naganuma et al. (2018)
Daucosterol	UPLC-APCI-TOFMS	0.0009216%	Naganuma et al. (2018)
Indican	UPLC-ESI-TOFMS	0.00001328%	Naganuma et al. (2018)
Anthranilic acid	UPLC-ESI -TOFMS	0.001356%	Naganuma et al. (2018)
Indigo	Q-TOFMS	13.81%	Wu et al. (2016)
Indirubin	Q-TOFMS	3.7%	Wu et al. (2016)
Tryptanthrin	Q-TOFMS	0.72%	Wu et al. (2016)
Isorhamnetin	Q-TOFMS	0.04%	Wu et al. (2016)
CaCO3	Titration	68.51%–71.50%	Wang (2004)
Silica	Titration	7.78–11.09%	Wang (2004)