A Simple Ultraperformance Liquid Chromatography-Tandem Mass Spectrometry Method for Measurement of Cortisol Level in Human Saliva

Table 2

Intra-and inter-run precision and accuracy of cortisol assay.

Nominal level; (ng/ml)	Intra-day (n=10)			Inter-day (n=20)
	Mean (SD); measured; level	CV; ()	Bias; ()	Mean (SD); measured; level	CV; ()	Bias; ()
0.5	0.52 (0.05)	9.0	3.2	0.51 (0.04)	8.4	2.2
1.5	1.42 (0.09)	6.0	-5.5	1.47 (0.11)	7.7	-2.0
50	52.77 (1.49)	2.8	5.1	53.27 (2.61)	4.9	6.5
90	100.79 (2.38)	2.4	12.0	99.23 (3.86)	3.9	10.3

SD: standard deviation. CV: coefficient of variation = standard deviation divided by mean measured concentration x 100. Bias = measured level - nominal level divided by nominal level x 100.