Indicators, absorption maxima indicator papers

Evidence for the production of ascorbic acids is that, after irradiation, the solution was able to decolorize solutions of 2,6-dichlorophenolindophenol and to produce a red color with an alkaline solution of triphenyltetrazolium chloride. The solution also displayed an absorption maximum at 245 m/u similar to that of L-ascorhic acid, and paper chromatography indicated the presence of a product running identically with L-ascorbic acid. The yield of the ascorbic acid was a function of the concentration, rising from G 0.16 at 5 X 10 ilf to G 0.95 at 4 X 10 M for a dose of 2.8 X 10 e.v. ml. of x-rays. The route to the ascorbic acid from the lactone may involve abstraction of a hydrogen atom at C-2 or C-3, followed by enoliza-tion. 

The 3 -p-azidobenzoyl ATP is prepared with p-azidobenzoic acid and ATP using carbodiimidazole as a catalyst as indicated above for the esterification of ATP with iV-2-BOC-a-alanine. The reaction mixture is subjected to chromatographic resolution with n-butanol water acetic acid (5 3 2) as solvent. The reaction product has a UV absorption band with an 22/ of 0.37. The material is eluted from the paper with water and found to have absorption peaks at 266 and 285 (sh) nm. Irradiation of the aqueous solution with UV light shifts the 266 nm absorption maximum to 257 nm. The starting p-azidobenzoic acid has a maximum absorption peak at 271 nm which is broadened by UV irradiation. 

Abscissa Accuracy and Reproducibility. These specifications determine the accuracy and precision with which the spectral position of absorption bands may be located. The abscissa accuracy, given as n Ou or cm ), indicates the maximum deviation between the measured and the true position of a band. Thus it is a measure of the calibration accuracy of the instrument. In the case of the more versatile instruments the abscissa reference may be a counter or dial reading. For the less versatile instruments the abscissa reference is generally the preprinted recorder paper located relative to a fiduciary mark on the recorder. 

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