Table 4. Intra- and inter-day precision of retention time, recovery and linearity (n = 5).

Analytes	RT precision (% RSD)		Recovery precision (% RSD) and mean recovery (%)									Linearity range (ppb)
	Intra-day	Inter-day	Mean recovery	Intra-day	Inter-day	Mean recovery	Intra-day	Inter-day	Meanrecovery	Intra-day	Inter-day
Fat-soluble vitamins			100 ppb			500 ppb			1000 ppb
Retinol (A)	0.054	0.146	99.16	0.28	0.54	103.55	0.28	0.43	99.72	0.22	0.31	100–1000
Ergocalciferol (D2)	0.085	0.152	97.60	0.16	0.43	100.30	0.20	0.31	99.30	0.23	0.35	100–1000
D-α-Tocopherol (E)	0.033	0.134	103.36	0.20	0.46	97.67	0.19	0.44	97.71	0.19	0.37	100–1000
Phylloquinone (K1)	0.009	0.022	101.91	0.37	0.46	97.74	0.18	0.35	97.79	0.29	0.35	100–1000
Water-soluble vitamins			10 ppb			50 ppb			100 ppb
Thiamine (B1)	0.137	0.140	107.07	0.17	0.41	98.74	0.22	0.41	98.77	0.29	0.40	10–100
Riboflavin (B2)	0.024	0.085	90.93	0.25	0.39	103.27	0.23	0.47	101.56	0.25	0.41	10–100
Nicotinic acid (B3)	0.172	0.196	88.95	0.29	0.52	100.63	0.27	0.42	100.30	0.28	0.42	10–100
Nicotinamide (B3)	0.078	0.125	90.58	0.26	0.45	101.62	0.26	0.45	101.68	0.26	0.36	10–100
D-Pantothenic acid (B5)	0.139	0.201	92.24	0.23	0.41	99.41	0.24	0.40	99.38	0.29	0.44	10–100
Pyridoxine (B6)	0.141	0.153	91.80	0.25	0.48	99.71	0.24	0.41	99.61	0.25	0.44	10–100
D-Biotin (B7)	0.041	0.110	99.23	0.23	0.48	98.35	0.23	0.42	98.77	0.28	0.32	10–100
Folic acid (B9)	0.049	0.092	95.81	0.24	0.52	102.88	0.24	0.43	102.33	0.29	0.32	10–100
Cyanocobalamin (B12)	0.162	0.192	89.53	0.25	0.51	99.71	0.23	0.40	99.84	0.22	0.41	10–100