title: Determination of attapulgite and nifuroxazide in pharmaceutical formulations by sequential digital derivative spectrophotometry.
abstract: A new method for the sequential determination of attapulgite and nifuroxazide in pharmaceutical formulations by first- and second-derivative spectrophotometry, respectively, has been developed. In order to obtain the optimal conditions for nifuroxazide stability, studies of solvent, light, and temperature effects were performed. The results show that a previous hydrolysis of 2 h in 1.0 x 10(-1)M NaOH solution is necessary in order to obtain stable compounds for analytical purposes. Subsequently, the first- and second-derivative spectra were evaluated directly in the same samples. The sequential determination of the drugs can be performed using the zero-crossing method; the attapulgite determination was carried out using the first derivative at 278.0 nm and the nifuroxazide determination, using the second derivative at 282.0 nm. The determination ranges were 5.7 x 10(-6)-1.0 x 10(-4) and 3.7 x 10(-8) -1.2 x 10(-4)M for attapulgite and nifuroxazide, respectively. Repeatability (relative standard deviation) values of 1.2 and 3.0% were observed for attapulgite and nifuroxazide, respectively. The ingredients commonly found in commercial pharmaceutical formulations do not interfere. The proposed method was applied to the determination of these drugs in tablets. Further, infrared spectroscopy and cyclic voltammetry studies were carried out in order to obtain knowledge of the decomposition products of nifuroxazide.
authors.affiliation: University of Chile, Department of Chemistry, Faculty of Sciences, Santiago, Chile.
authors.forename: M Inés
authors.initials: MI
authors.lastname: Toral
authors.forename: Maximiliano
authors.initials: M
authors.lastname: Paine
authors.forename: Patricio
authors.initials: P
authors.lastname: Leyton
authors.forename: Pablo
authors.initials: P
authors.lastname: Richter
mesh_terms: D000890:Anti-Infective Agents / Q000032:analysis*; D002138:Calibration; D002626:Chemistry, Pharmaceutical; D006868:Hydrolysis; D062385:Hydroxybenzoates / Q000032:analysis*; D007202:Indicators and Reagents; D008027:Light; D017616:Magnesium Compounds / Q000032:analysis*; D009581:Nitrofurans / Q000032:analysis*; D015203:Reproducibility of Results; D017655:Silicon Compounds / Q000032:analysis*; D012972:Sodium Hydroxide; D012997:Solvents; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet; D013607:Tablets; D013696:Temperature
chemical_list: D000890:Anti-Infective Agents; D062385:Hydroxybenzoates; D007202:Indicators and Reagents; D017616:Magnesium Compounds; D009581:Nitrofurans; D017655:Silicon Compounds; D012997:Solvents; D013607:Tablets; D012972:Sodium Hydroxide; C013150:nifuroxazide; C026325:attapulgite