title: Green method by diffuse reflectance infrared spectroscopy and spectral region selection for the quantification of sulphamethoxazole and trimethoprim in pharmaceutical formulations.
abstract: An alternative method for the quantification of sulphametoxazole (SMZ) and trimethoprim (TMP) using diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) and partial least square regression (PLS) was developed. Interval Partial Least Square (iPLS) and Synergy Partial Least Square (siPLS) were applied to select a spectral range that provided the lowest prediction error in comparison to the full-spectrum model. Fifteen commercial tablet formulations and forty-nine synthetic samples were used. The ranges of concentration considered were 400 to 900 mg g-1SMZ and 80 to 240 mg g-1 TMP. Spectral data were recorded between 600 and 4000 cm-1 with a 4 cm-1 resolution by Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). The proposed procedure was compared to high performance liquid chromatography (HPLC). The results obtained from the root mean square error of prediction (RMSEP), during the validation of the models for samples of sulphamethoxazole (SMZ) and trimethoprim (TMP) using siPLS, demonstrate that this approach is a valid technique for use in quantitative analysis of pharmaceutical formulations. The selected interval algorithm allowed building regression models with minor errors when compared to the full spectrum PLS model. A RMSEP of 13.03 mg g-1for SMZ and 4.88 mg g-1 for TMP was obtained after the selection the best spectral regions by siPLS.
authors.affiliation: Departamento de Farmácia, Universidade Federal do Pampa, Uruguaiana, RS, Brasil.
authors.forename: Fabiana E B
authors.initials: FE
authors.lastname: da Silva
authors.affiliation: Departamento de Química, Universidade Federal de Santa Maria, Santa Maria, RS, Brasil.
authors.forename: Érico M M
authors.initials: ÉM
authors.lastname: Flores
authors.affiliation: Departamento de Química, Universidade Federal de Santa Maria, Santa Maria, RS, Brasil.
authors.forename: Graciele
authors.initials: G
authors.lastname: Parisotto
authors.affiliation: Departamento de Química, Universidade Federal de Santa Maria, Santa Maria, RS, Brasil.
authors.forename: Edson I
authors.initials: EI
authors.lastname: Müller
authors.affiliation: Departamento de Química Inorgânica, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil.
authors.forename: Marco F
authors.initials: MF
authors.lastname: Ferrão
mesh_terms: D002138:Calibration; D002851:Chromatography, High Pressure Liquid; D016018:Least-Squares Analysis; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D013420:Sulfamethoxazole / Q000032:analysis*; D014295:Trimethoprim / Q000032:analysis*
chemical_list: D014295:Trimethoprim; D013420:Sulfamethoxazole