Multi-user Equipment approved in grant 2014/50951-4: Instituto Nacional de Ciências e Tecnologias Analíticas Avançadas (INCTAA). Compact interferometer with Fourier transform

Abstract

This Multi-User Equipment project aims to acquire a compact interferometer with Fourier transform that can operate in the NIR and MID region, with or without optical fibers to be used in near infrared emission spectrometric (NIRES) measurements. This technique was developed in the Instrumentation and Automation Group in Analytical Chemistry at IQ-UNICAMP and its application has been demonstrated in several research works developed over the years. To explore the analytical potential of the NIRES technique, prototypes of the NIR emission spectrometer were built based on a tunable optical acoustic filter (AOTF) as a wavelength selector. The NIRES-AOTF spectrometers have a resolution of about 5 nm and take about 45 s to obtain 1 spectrum. The measurements are made at a predetermined fixed temperature (above 150 oC), however, during this period, there is a fluctuation of approximately 1 oC in the heating system, which is responsible for a significant part of the variability of the measurements. Thus, in order to minimize this source of variability in emission measurements, it is proposed to develop an new equipment based on Fourier Transform (FT) which, being considerably faster in the acquisition of the spectra, would allow less temperature fluctuation during the measurements. Additionally, FTNIRES would allow an accumulation of a greater number of scans, which possibly will produce spectra with a higher signal / noise ratio, in addition to a much higher spectral resolution when compared to NIRES-AOTF. Due to the expected improvement in the signal / noise ratio, FTNIRES will possibly allow the use of lower excitation temperatures and, consequently, a greater variety of samples can be used in the development of analytical applications. After evaluating the performance of the FTNIRES spectrometer, it is proposed that the instrument is used in the development of methods for the determination of organic matter in soils, determination of ash in plant matrices, determination of quality parameters of honey samples and in the monitoring of reactions chemicals that occur in a solid state at high temperatures. (AU)