Triton X-100-stabilized "oil-in-water" emulsions as suitable media for alkalimetric determination of hydrophobic organic acids

Abstract

The protolytic properties of fat row carbonic acids in Triton X-100-stabilized "oil-in-water" (O/W) emulsions were studied. The differential influence of emulsions on the force of acids was shown to depend on the length of the hydrocarbon radical. The conditions for separate alkalimetric determinations of acids with different hydrophobicities in their mixtures using emulsions stabilized by non-ionic surfactant were suggested. The procedure for the determination of 4-chloro- N-(2-furilmethyl)-5-sulfamoylanthranilic acid (furosemide) main substance content in pharmaceuticals using Triton X-100-stabilized emulsion was proposed.

Recent developments in analytical determination of furosemide

“…The procedure for the determination of FUR main substance content in pharmaceuticals using Triton X-100-stabilized emulsion was recommended to dissolve the sample of FUR (0.05-0.10 g) in the emulsion of 0.25 g of oil in 25 mL 2.5% Triton X-100 solution. The titration is performed with 0.025 M KOH aqueous solution and the equivalent point was determined from the differential titration curve or by addition of bromothymol blue solution until to the emulsion colour changed from yellow to blue [7]. Recently, an acidified solution of FUR is titrated directly with bromate-bromide mixture using methyl orange as indicator and applicable over 2-20 mg range [8].…”

System of indicators for acid-base titration in surfactant-stabilized emulsions

“…It was shown earlier that 0.1 M surfactant solutions ensure an acceptable stability and emulsifying power of the resulting emulsions [4,7].…”

“…A logical development of this trend is to use surfactant-stabilized "oil-in-water" type emulsions (o/w-type emulsions) as the titration media. The use of emulsions frequently makes it possible to produce micellar media with a solubilization capacity (relative to the most hydrophobic organic compounds) high enough for titrimetric determinations [4][5][6][7]. Optimized emulsions are easy to work with and are stable against aggregation and sedimentation [8,9].…”

“…These media are convenient and pollution-free alternatives to toxic organic solvents in the titrimetric determination of hydrophobic protolytes [1][2][3][4][5][6][7]. The use of aqueous surfactant solutions allows one to change the acid-base properties of solubilized compounds in a controlled way.…”

The interaction between furosemide-palladium (II) chelate and basic triphenylmethane dyes by resonance Rayleigh scattering spectra and resonance non-linear scattering spectra and their analytical applications

“…Various analysis and detection methods [5] have been developed for the determination of FUR, mainly including titration [6][7][8][9][10], spectrophotometry [11][12][13][14], spectrofluorimetry [15][16][17][18][19], liquid chromatography [20][21][22], electroanalytical methods [23,24] and chemiluminescence [4,[25][26][27]. Among them, titration has low sensitivity and is problematic to judge the end point, and only high concentration of FUR could be determined by this method.…”