Espectroscopia no infravermelho proximo com o uso de filtro optico-acustico sintonizavel

AUTOR(ES)
DATA DE PUBLICAÇÃO

2000

RESUMO

This work describes the construction of a near infrared spectrophotometer that employs a monochromator element based on an acoustic-optic tunable filter set to work on absorbance and reflectance modes. The instrument is controlled by a microcomputer and the necessary programs to perform the instrument control and data acquisition/storage were written in MS-Visual Basic and MS-Visual C++. The wavelength difference between the two emergent beams from AOTF was found to be, in average, 0.25 nm, which a1lowed the construction of a dual beam instrument with a standard deviation of 1x10 Absorbance. The average precision in wavelength selection is 0.06 nm. Two analytical methods was developed employing absorbance measurements; determination of total content of olefins with multivariate calibration (PLS) with standard error of prediction (SEP) equal to 0.12% and determination of water in ethanol with an univariate calibration (linear regression) SEP = 0.07%. Also, the following methods employing reflectance measurements were developed; determination of ICUMSA color of sugars (PLS) capable to predict correctly 79% of samples, determination of geographic origin and flora origin of propolis by principal component analysis (PCA), with reasonable correlation, determination of phenolic contents of propolis (PLS) with SEP = 3.0% when compared with the titration method and 1.9% for calibration with HPLC and determination of flavonoid content (PLS) SEP 0.53% and 1.0%, when compared with wet and HPLC methods, respectively.

ASSUNTO(S)

espectroscopia de infravermelho propole

ACESSO AO ARTIGO

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