Table 1.

Parameters for linear regression function, ^†*Limit of detection (LOD) and ^†*limit of quantitation (LOQ) for six KP metabolites in human plasma.

Analyte	Linearity Range (μg/mL)	Correlation Coefficient	Calibration Curve	S/N at experimental LOD	LOD (experimental), nM	S/N at experimental LOQ	LOQ (experimental), nM
TRP	14.4–57.6	0.9994	y = 20.1(±0.3) × − 50.3(±0.4)	3	31	832	10,000
KYN	0.8–3.4	0.9986	y = 55(±2) × − 1.14(±0.05)	4	250	15	506
AA	14–137	0.9981	y = 3.05(±0.04) × −0.083(±0.003)	2	50	8	100
KA	9–190	0.9999	y = 3.8(±0.3) × − 0.048(±0.003)	7	50	9	100
PA	12–118	0.9990	y = 6.5(±0.4) × − 0.002(±0.003)	2	100	10	1000
QA	33–900	0.9995	y = 58(±7) × − 0.28(±0.02)	5	50	8	100

^*The LOD is defined as the concentration at which S/N = 2 and LOQ is defined as the concentration at which S/N = 10.

^†The injection sizes used in LOD measurement are: 5 mbar, 100 s for TRP, KYN, AA and HKYN, 5 mbar X 50 s for KYNA, QA, HAA, and PA, 5 mbar X 25 s for XA. The Injection sizes used in LOQ measurement are 5 mbar X 100 s for TRP, and KYN, 5 mbar X 50 s for KYNA, QA, HAA and AA, 5 mbar X 25 s for HKYN, and XA, 5 mbar X 10 s for PA.