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Table 3 Principal positive ions that increase during aging. Retention time, measured m/z, calculated m/z, postulated identity, and elemental composition of positive ions that increase during aging.

From: 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

Retention time (min) Measured m/z (Da) Calculated m/z (Da) Postulated identity (with tR of standard) Elemental composition of [M+H] ion
2.14 212.1061 212.0324 Kynurenic acid Na C10H7NO3Na
2.25 231.1701 231.1695   C9H21N5O2
5.83 180.0659 180.0661 Hippuric acid (5.83) C9H10NO3