Establishment of Quality Evaluation Method for Yinqiao Powder: A Herbal Formula against COVID-19 in China

Table 6

Linear regression equation of seven reference substances.

Wavelength (nm)	Reference substance	Regression equations	R	Linear range (μg)
237	Forsythoside A	y = 26.30x + 0.073	0.9995	0.1776–2.96
	Phillyrin	y = 21.89x + 0.024	0.9995	0.0165–0.275
	Arctiin	y = 22.68x + 0.073	0.9995	0.0678–1.130
327	Forsythoside A	y = 43.42x + 0.065	0.9995	0.1776–2.960
	Neochlorogenic acid	y = 94.10x + 0.048	0.9995	0.00462–0.077
	Chlorogenic acid	y = 70.02x + 0.027	0.9995	0.0576–0.960
	Isochlorogenic acid A	y = 68.79x − 0.420	0.9995	0.039–0.650
	Isochlorogenic acid C	y = 78.88x − 0.090	0.9995	0.00912–0.152