Table 2. LF analytical performance and range.

Mean, SD, accuracy (% error), precision (% CV), and analytical ranges (bold font) for LF plasma calibration standards, plasma blank (PBL), and quality control samples (QCs), for 4-h and ON methods compiled from analysis of 100 sets on 100 days. Results for % error and % CV that are within acceptable ranges ≤ 20% are indicated in italics. The optimum quantitative ranges are shown in bold font for Observed Values and represent standards levels of 0.11–11.8 ng/mL for the 4-h and 0.003–0.938 for the ON methods. The lowest standard level for the calculated LOD is 0.011 for the 4-h method and 0.003 for the ON method (underlined).

LF Standard	Expected (ng/mL)	4-Hour Method (4-h)			Overnight Method (ON)
		Observed (ng/mL)	% Error	CV (%)	Observed (ng/mL)	% Error	CV (%)
S1	11.8	10.9	7.4	7.3	6.0	49	48
S2	6.25	6.5	4.6	7.4	4.3	31	44
S3	3.32	3.47	4.6	5.7	3.3	0.45	36
S4	1.76	1.80	2.5	5.9	1.93	9.5	17.4
S5	0.938	0.91	3.2	5.3	1.01	7.2	12.3
S6	0.498	0.488	2.1	7.0	0.506	1.5	9.0
S7	0.265	0.262	1.2	4.2	0.253	4.5	6.0
S8	0.141	0.143	1.1	7.9	0.138	2.5	9.4
S9	0.075	0.076	1.6	13	0.077	2.3	8.4
S10	0.040	0.040	1.0	10	0.040	1.3	8.0
S11	0.0211	0.021	1.3	20	0.022	2.2	6.4
S12	0.011	0.012	5.3	25	0.011	0.2	7.4
S13	0.006	0.007	24	39	0.006	1.5	10.6
S14	0.003	0.004	23	27	0.0033	4.7	15.7
PBL	0	0.002	NA	NA	0.0004	NA	NA
QCH	0.722	0.700	3.0	14.8	0.725	0.41	14.2
QCM	0.203	0.20	2.6	11.0	0.192	5.4	7.7
QCL	0.044	0.045	3.3	16.2	0.046	3.8	8.6