Spectrophotometric Determination of Sulfaquinoxaline

Abstract

The suitability of the Bratton-MarshaH color reaction as the basis for a spectrophotometric assay of sulfaquinoxaline was investigated using iY-(lnaphthyl)-ethylenediamine dihydrochloride as the coupling agent. Because a nonlinear relationship between concentration and color intensity obtains in the adopted procedure, extinction coefficients were determined at several concentrations.The effects of acidity and salt concentrations on the color SULFAQUINOXALINE {15) (2-sulfanilamidoquinoxaline) has been found {2, S, 5, 12) to be an effective chemotherapeutic agent for the prevention and control of certain poultry diseases. Being a sulfonamide in which sulfanilic acid is condensed with 2-aminoquinoxaline, it shows the typical color reaction that is the basis of the assay method proposed by Marshall {1, 8-11) and colleagues for sulfanilamide and related compounds. The color is generated by diazotization of the free arylamino group and coupling with a suitable agent.Of the large number of coupling agents examined {1), Af-(l-naphthyl)-ethylenediamine dihydrochloride was cited by Bratton and Marshall as the most satisfactory. The present authors have studied this reaction spectrophotometrically in the case of sulfaquinoxaline and find that, despite the many factors that influence the color intensity, it may be made the basis of an analytical method. The resulting colored compound has the same visible absorption spectrum as the azo dye obtained from sulfanilamide (I), exhibiting a characteristic band at 545 mg.The method was tested with a number of sulfaquinoxaline samples of known purity and was applied to mixtures with inorganic diluents. An extension to mixtures of sulfaquinoxaline with an organic diluent, such as poultry feed, which requires extraction of the sulfonamide is also described. SPECTROPHOTOMETRIC STUDYReagents. The following aqueous reagents were employed in this investigation: 0.02 N and 0.50 N solutions of hydrochloric acid, 0.5 N solution of sodium hydroxide, 0.1% solution of sodium nitrite, 0.5% solution of ammonium sulfamate (La Motte "purestandardized"), 0.1% solution of N-(1 -naphthyl)-ethylenediamine dihydrochloride (Eastman Kodak), and sodium chloride. Unless otherwise stated, Merck reagent grade chemicals were employed. The coupling agent was stored in a dark-colored glass bottle to avoid photodeterioration. Fresh sodium nitrite solution was prepared daily. The concentration of the 0.50 N acid had to be regulated fairly accurately because pH control was necessary for reproducible color production.

Schiff Base Formation in the Development of a Spectrophotometric Assay for Sulfonamides

“…In the latter method, absorbance readings must be made within 15 min. after color development, due to precipitation of the azo dyes formed in the method (9). In determinations of low concentrations of sulfanilamide, it was found that the method was sensitive t o sulfanilamide concentrations of approximately 0.5 mcg./ml.…”

“…Thus, it eliminates the need for freshly prepared sodium nitrite solutions and ammonium sulfamate solutions required with the method of Bratton and Marshall. Control of pH and ionic strength are required in both methods (9).…”

“…For the analysis by the method of Bratton and Marshall, the procedure followed was that outlined by Dux and Rosenblum (9).…”

Improved Colorimetric Determination of Primary Aromatic Amines with 9-Chloroacridine: Application to Some Local Anesthetics

“…In the latter method, absorbance readings must be made within 15 min. after color development, due to precipitation of the azo dyes in the method (7). The 9-chloroacridine method also does not involve diazotization.…”

Comparison of Procainamide Analyses in Plasma by Spectrophotofluorometry, Colorimetry, and GLC

“…Procainamide (as well as other drugs containing a primary &mine on an aromatic ring) has most often been determined by diazotization, coupling with N -(l-naphthyl)ethylenediamine, and subsequent colorimetric analysis (5). While this procedure has been used for a long time (6), it requires 1-2 hr for a single assay, sodium nitrite and ammonium sulfamate solutions must be prepared at the time of analysis, and the color produced is unstable (7). The utility of direct spectrophotofluorometry for this determination has been investigated (3).…”