Table 2.

Intra- and interday accuracy and precision of high-performance liquid chromatography assay for gastrodin from water extracts of Gastrodia elata Blume.

Analyst	Level (μg/mL)	Injection	Recovery			Recovery (%)	Average (n = 3)	RSD (%)	Repeatability		Intermediate
			Standarda	Sampleb (μg/mL)	Spikec				Average (n = 9)	RSD (%)	Average (n = 27)	RSD (%)
1	30	1	30.75	27.04	29.08	101.20	102.67	1.28	100.81	2.77	100.22	3.23
		2	29.64	27.78	29.27	103.75
		3	30.38	27.97	29.64	103.05
	50	1	49.27	48.72	50.20	104.89	101.88	2.53
		2	50.39	48.53	49.27	99.26
		3	49.46	46.87	48.53	101.50
	70	1	69.65	67.06	67.24	96.81	97.87	2.72
		2	69.28	68.73	68.73	99.20
		3	69.47	68.17	67.98	97.60
2	30	1	29.45	29.27	29.08	98.11	96.84	1.45	97.98	2.34
		2	29.64	29.08	28.71	95.62
		3	28.71	30.38	29.08	96.77
	50	1	48.90	48.53	47.79	96.21	99.62	1.46
		2	49.27	48.16	49.27	102.26
		3	47.61	48.90	48.35	100.39
	70	1	68.54	68.91	67.24	95.68	97.47	1.15
		2	68.17	68.54	67.43	97.28
		3	67.43	68.17	67.61	99.45
3	30	1	31.81	31.81	31.98	101.08	99.10	3.97	101.87	3.38
		2	31.63	33.01	31.46	94.56
		3	31.29	32.49	32.15	101.65
	50	1	52.10	49.69	52.44	105.94	104.64	1.90
		2	51.93	49.69	52.27	105.63
		3	51.24	50.38	51.41	102.35
	70	1	74.11	72.56	74.80	103.94	101.87	2.18
		2	73.94	71.19	72.39	99.53
		3	73.08	73.94	74.28	102.12

RSD = relative standard deviation; Sample = determination of gastrodin content by injecting each sample preparation; Spike = determination of gastrodin content by injecting each spiked solution; Standard = determination of gastrodin content by injecting each standard solution.

^aStandard: determination of gastrodin content by injecting each standard solution.

^bSample: determination of gastrodin content by injecting each sample preparation.

^cSpike: determination of gastrodin content by injecting each spiked solution.