Organic acids observed and quantified prior to GC-MS

In addition to these acids, ascorbic acid, dehydroascorbic acid, glucuronic acid and furan-2,5-dicarboxylic acid also occur among the aliphatic acids in urine. Knowledge of the aromatic acids again improved with the introduction of paper chromatography (Armstrong et al.y 1956), and acids reported to occur 

Blood plasma Whole blood Urine clearance 

3-Hydroxyphenylhydracrylic 3-hydroxybenzoic Homovanillic (3-methoxy-4-hydroxyphenylacetic) Vanilmandelic (3-methoxy-4-hydroxymandelic) 

The occurrence of these acids, as detected and determined by techniques other than GC-MS, together with references to the original reports are given by Nordmann and Nordmann (1961), to which the reader is strongly referred. Table 7.1. lists the acids observed for which quantitative levels in blood and urine have been reported. 

---