Quantitative Measurement of Plasma Free Metanephrines by a Simple and Cost-Effective Microextraction Packed Sorbent with Porous Graphitic Carbon and Liquid Chromatography-Tandem Mass Spectrometry

Table 1

Intra- and interday assay imprecision and accuracy (spiked QC samples: LQC, MQC, & HQC and Chromsystems QC: C1 & C2).

Compund	Sample	Added/expected (pg/mL)	Intraday					Interday
			Mean (ng/mL)	SD	CV (%)	Accuracy (%)	Mean (ng/mL)	SD	CV (%)	Accuracy (%)
MN	LQC	100	108	10	9.4	108.0	108	10	9.7	108.0
	MQC	500	481	43	9.0	96.2	516	42	8.2	103.2
	HQC	2000	1899	150	7.9	95.0	2030	152	7.5	101.5
	C1	60	58.9	8.0	13.6	98.2	62.9	8.5	13.4	104.8
	C2	750	708	62	8.7	94.4	729	56	7.7	97.2
NMN	LQC	150	141	18	12.8	94.0	151	16	10.7	100.7
	MQC	750	811	79	9.8	108.1	781	68	8.7	104.1
	HQC	3500	3310	105	3.2	94.6	3100	182	5.9	88.6
	C1	100	103	8	8.0	103.0	109	9	8.6	109.0
	C2	3500	3080	68	2.2	88.0	3460	224	6.5	98.9