Table I.

Calculated slopes from calibration curves prepared in urine (matrix) and hexane (nonmatrix). Differences in the averages of the three slopes, obtained from each calibration set, are minimal and validates use of a nonmatrix calibration set to quantitate AAs in urine.

Analyte	LoD (ng/L)	Hexane and urine calibration range (pg/μL)	Hexane calibration curve, slope			Hexane, averaged slopes	Urine calibration curve, slope			Urine, averaged slopes		Difference in averaged slopes (%)
			Run 1	Run 2	Run 3		Run 1	Run 2	Run 3
OTOL	111.2	0.507–1,280	0.01811	0.01673	0.01753	0.01746	0.01768	0.01688	0.01598	0.01685		3.49
26DM	15.7	0.502–100	0.01613	0.01567	0.01563	0.01581	0.01643	0.01573	0.01611	0.01609		−1.76
OANS	7.0	0.504–99.9	0.01164	0.01144	0.01160	0.01156	0.01153	0.01099	0.01141	0.01131		2.19
1AMN	1.5	0.504–99.9	0.03636	0.03736	0.03735	0.03702	0.03553	0.03610	0.03579	0.03579		3.33
2AMN	2.8	0.489–100	0.02788	0.02850	0.02849	0.02829	0.02924	0.02948	0.02932	0.02932		−3.64
4ABP	1.8	0.482–98.6	0.00699	0.00698	0.00673	0.00690	0.00712	0.00716	0.00708	0.00708		−2.62