Table 3.

Intraday and interday precision and accuracy for the tetracycline drugs.

Compound	Standard concentration (µg/mL)	Mean % recovery ± SD	RSD (%)a	Er (%)b	Mean % recovery ± SD	RSD (%)a	Er (%)b
		Intraday precision and accuracy (n = 3)			Interday precision and accuracy (n = 9)
OXY	0.1	97.90 ± 0.98	1.01	− 2.099	97.68 ± 1.12	1.15	− 2.32
	0.5	100.87 ± 2.08	0.41	0.87	99.72 ± 6.7	1.34	− 0.28
	0.8	100.21 ± 1.82	0.23	0.21	99.80 ± 2.79	0.35	− 0.20
TTR	0.1	100.41 ± 1.68	1.67	0.41	100.48 ± 1.88	1.87	0.48
	0.5	99.66 ± 4.01	0.80	− 0.34	98.89 ± 7.3	1.48	− 1.11
	0.8	99.52 ± 2.14	0.27	− 0.48	98.50 ± 6.91	0.88	− 1.50
CTC	0.1	99.10 ± 1.28	1.29	− 0.90	99.00 ± 1.27	1.29	− 1.00
	0.5	100.28 ± 1.32	0.26	0.28	99.64 ± 3.82	0.77	− 0.36
	0.8	99.95 ± 2.26	0.28	− 0.05	99.91 ± 2.37	0.30	− 0.09

^aRSD (%) Percentage relative standard deviation.

^bEr (%) Percentage relative error.