Indirect spectrophotometric determination of oxalate using uranium and 4-(2-pyridylazo)resorcinol

Abstract

Precision. On the same day, a single penicillin V fermentation sample of a series was analyzed 71 times. The following results were obtained: Average value of 8764 units per milliliter with a relative standard deviation of 0.9%. Dayto-day (TV = 50) analyses of penicillin V fermentation samples gave an average value of 7710 units per milliliter with a relative standard deviation of 2.4%.The AutoAnalyzer Method vs. the Manual Method. The two methods agreed with a correlation coefficient of 0.97Interference. Only a few substances are able to reduce a molybdoarsenic acid-mercuric chloride reagent at room temperature. Among these are strongly reducing salts such as ferro and stanno salts, as well as ascorbic acid and hydroquinone. These substances were not found in any measurable concentrations in the fermentation substrates which were used. However, degradation products of penicillin, such as penicilloic acid, penilloic acid, penillic acid, and penicillamine may be found. Penicilloic acid, the active agent in the method, reacts with molybdoarsenic acid-mercuric chloride to the greatest extent. Penilloic acid interfered slightly (less than 10%), whereas penillic acid and penicillamine exerted strong interference, e.g., 10 mg of penicillamine per milliliter gave a reading corresponding to 10000 units of penicillin G per milliliter. However, this interference did not affect the final calculated penicillin concentration, since the blank corrected for interference of this nature.Conclusion. The AutoAnalyzer modification of Pan's procedure results in a method with a high order of specificity, accuracy, precision, and speed of analysis, as well as a high sensitivity. In addition, only very small amounts of sample are required for each analysis. ACKNOWLEDGMENTThe author is very grateful to P. W. Hansen for his valuable help during the preparation of this manuscript.

Investigation of the Interaction of Gadolinium with Several Organic Ligands and Humic Acid by Ligand Competition Using 4-(2-Pyridylazo)-Resorcinol (PAR)

“…Degnall et al [11] indicated that a 1:1 Pb 2+ -PAR complex was formed. Neas and Guyon (1972) [12] developed a method for the indirect determination of oxalate using the competitive disruption of the highly colored uranium and PAR complex by oxalate at pH 4.8. Florence and Farrar (1963) [13] used PAR for a spectrophotometric determination of uranium.…”