Anion-exchange
chromatography in acetate media is a valuable tool in the analysis of mistures cont;tining several uranic acids. Acetic acid'-3 and sodium acetated. have heen used as eluants by various authors whose working conditions have differed in many respects. Acetic acid has also been used in preparative work. Some contradictory results have been reported. The aim of this work was to devise an automated method for the determination of uranic acicls after separation on anion-cscliange resins. In acldition to the 5 more common hcsuronic acids, .+-0-methyl-n-glucuronic acid was included. For comparison, some biouronic acicls and some other hydrosy acids of interest in carbohydrate chemistry were chrolnatographccl.
A dctailecl discussion of the optimum conditions for a mutual separation of these acids is, however, outside the scope of this work. 130th acetic acicl and sodium acetate were used as eluants.
In earlier work on anion-eschange separations of organic acids, fractions from a fraction collector were transferred into the sampling device of a Tcchnicon Auto-Analyzer.
The acids were oxidized with clichromate and the remaining dichromate determined automatically by its reaction with diphenylcarbaziclc". Compared with the manual method of titration or calorimetric determinations, this method was much faster. In the pr&ent work the cluate was passed directly into a monitor which consisted of a peristaltic pump, reaction coils, ancl a multiclianncl photometer with a recorder.
Ry means of the peristaltic pump the eluatc was divided into 3 streams. One of these was used for automatic determination of uranic acids l_,y a carbazole method. The second stream of the eluate was oxiclisled by chromic acid to determine all osidizable organic acids, ancl the rest went into an automatic fraction collector where fractions were taken for additional identification.
This simultaneous recording of 2 different analyses from the same run is extremely valuable when other acids in addition to uranic acids are present. The information obtained from both these types of analysis is very useful 7, but with the old system much time was required to obtain it. The principle of the analytical system is given in Fig. I. Results reported by SWANN et al. 8 facilitated the choice of conditions for the carbazole reaction. The conditions were, however, simplified in various respects. Three tubings were used in the peristaltic pump, one with the eluate, one with the carbazole reagent and one with sulfuric acid. An excessively high sulfuric acid con-.d?lal. CJlint. Acta, 30 (fQ66) I--II AUTOMATIC CHROMATOGIIRI'HY 01: UROSIC hC1D.S