Determination of Polyphenol Components of Korean Prostrate Spurge (Euphorbia supina) by Using Liquid Chromatography—Tandem Mass Spectrometry: Overall Contribution to Antioxidant Activity

Table 2

Regression data, limit of detection (LOD), and limit of quantification (LOQ) for the five external standards.

Standard	Calibration curve	𝑟^2	LOD	LOQ	Recovery (%) ± RSD
			(mg/L)	(mg/L)	50 mg/L	100 mg/L
Gallic acid	𝑦=25.171𝑥+335.04	0.9993	0.032	0.107	79.6±6.1	85.2±0.5
Protocatechuic acid	𝑦=37.614𝑥+1137.3	0.9982	0.030	0.102	88.5±0.2	87.8±0.5
7-Hydroxycoumarin	𝑦=10.873𝑥−28.39	0.9955	0.142	0.473	102.8±0.7	98.6±11.6
Quercetin 3-O-glucoside	𝑦=30.166𝑥+267.56	0.9949	0.037	0.125	76.1±0.1	90.9±14.0
Kaempferol	𝑦=39.493𝑥+1475.4	0.9907	0.028	0.094	100.0±3.0	97.4±1.4

𝑦: peak area of standard; 𝑥: concentration of standard (mg/L).