Table 1. Pooled Human Serum and Blank Samples Used in the Study.

method	NMR experiment	number
ultrafiltration-serum	1H 1D NMR (filtrate dried)	2
	1H 1D NMR (filtrate not dried)	2
	15N-cholamine tagging and 2D NMR	2
methanol precipitation	1H 1D NMR	2
	15N-cholamine tagging and 2D NMR	2
multiple (3-fold) methanol precipitation	1H 1D NMR	2
intact serum	1H 1D NMR	2
acetonitrile precipitation	1H 1D NMR	2
perchloric acid precipitation	1H 1D NMR	2
trichloroacetic acid precipitation	1H 1D NMR	2
ultrafiltration-blank	1H 1D NMR	2