Table 1.

Accuracy of the determination of crocetin in human serum (n= 5)

Direct precipitation		Solid phase extraction		Bias (%)		Accuracy
Cnominal (µg/ml)	C measured (µg/ml)	Cnominal (µg/ml)	C measured (µg/ml)	Direct precipitation	Solid phase extraction	Direct precipitation	Solid phase extraction
0.05	0.0496	0.5	0.6171	-0.83	+23.42	99.17	76.58
0.1	0.0909	1	1.1333	-9.091	+13.33	90.91	86.67
0.25	0.2562	1.25	1.2625	2.48	+0.9988	102.48	99.00
0.5	0.5041	1.75	1.567	0.83	-10.45	100.83	110.45
1	1	2.5	2.3031	0	-7.88	100	107.88
1.25	1.2479	5	5.137	-0.17	+2.77	99.83	97.26