Table 4.

Intra-day and inter-day accuracy (% bias) and precision (% RSD) of spiked urines at three different concentrations. Samples were analyzed in triplicate. Inter-day data were estimated from spiked urine samples analyzed for five different days over several weeks (n=15)

		Intra-Day			Inter-Day
Analyte	Actual Concentration (ng/mL)	Calculated Concentration (ng/mL)	Bias (%)	RSD (%)	Calculated Concentration (ng/mL)	Bias (%)	RSD (%)
PPDA	0.50	0.53	6.0	6.0	0.54	8.0	8.30
	2.45	2.20	−10.2	4.0	2.78	13.5	6.58
	24.5	25.1	2.5	3.7	26.2	6.9	3.58
6TDA	0.48	0.47	−2.1	3.8	0.45	−6.3	7.60
	2.45	2.40	−2.0	4.5	2.50	2.0	4.44
	24.4	25.2	3.3	1.5	27.4	12.3	2.06
4TDA	0.49	0.44	−10.2	2.0	0.51	4.1	3.42
	2.44	2.39	−2.0	2.4	2.52	3.3	4.49
	24.4	24.6	0.90	2.7	27.0	10.7	2.59
NDA	0.50	0.47	−6.0	2.3	0.51	2.0	7.14
	2.51	2.58	2.8	2.6	2.33	−7.2	2.28
	25.1	25.3	0.8	2.7	24.0	−4.4	2.41
MDA	0.16	0.162	1.25	2.7	0.17	6.3	5.09
	0.51	0.525	2.94	1.0	0.58	13.7	2.76
	5.10	5.06	−0.78	2.5	5.00	−2.0	5.09