Table 2. Validation parameters of HPLC-PDA for analysis of ergothioneine in G. elata rhizome

Parameter	Value
Regression equation	y=55237x-21674
Coefficient of determination (R2)	0.9998
Linear range (μg/mL)	1.953-250
LOD1) (μg/mL)	4.12
LOQ2) (μg/mL)	12.48
Precision	SD (RSD%)
Intra-day	2.00 (1.64)
Inter-day	1.68 (1.37)
Spike amount (μg/g DW3))	Recovery (%, Mean±SD)
1,000	98.23±2.58
500	99.68±2.68
250	102.97±2.48

LOD, limit of detection; LOD=3.3×standard deviation/slope.
LOQ, limit of quantitation; LOQ=10×standard deviation/slope.
DW, distilled water.