Metabonomics evaluations of age-related changes in the urinary compositions of male Sprague Dawley rats and effects of data normalization methods on statistical and quantitative analysis

Table 5 Principal negative ions that increase during aging. Retention time, measured m/z, calculated m/z, postulated identity, and elemental composition of negative ions that increase during aging.

Retention time (min)	Measured m/z (Da)	Calculated m/z (Da)	Postulated identity (with t_R of standard)	Elemental composition of [M+H] ion
2.38	224.0210
2.40	468.0941
3.53	252.0544
4.62	247.1055	247.1083	6-Hydroxymelatonin (4.59)	C₁₃H₁₅N₂O₃
4.78	276.0547
4.85	308.1167
5.50	273.0063	273.0069	Ferulic acid sulfate	C₁₀H₉SO₇
5.53	275.0220	275.0225		C₁₀H₁₁SO₇
6.14	222.0764
6.93	173.0806	173.0814	Suberic acid (6.92)	C₈H₁₃O₄

ISSN: 1471-2105