Three different Fourier‐transform mid‐infrared sampling techniques to characterize bio‐organic samples

Abstract

In recent years, there has been a surge in the number of applications of Fouriertransform mid-infrared (FTIR) spectroscopy for the characterization of environmental samples and prediction of some of their properties whose measurement has traditionally involved time-consuming and costly methods. However, there are several different mid-infrared techniques available, and there is a gap in knowledge regarding the best-suited technique for recording informative spectra of different types of environmental samples. This study compared the three most widespread FTIR techniques using solid and liquid samples. A total of 11 environmental samples belonging to four categories were analyzed with attenuated total reflectance (ATR), photoacoustic (PAS), and diffuse reflectance (DR) FTIR spectroscopy. Overall, PAS-FTIR was the best technique, providing a greater amount of information, especially for opaque samples (i.e., organic waste, biochar, and soil), than ATR-FTIR and DR-FTIR spectroscopy. Attenuated total reflectance FTIR provided the best spectra for soft samples, such as plant materials, probably due to their ability to achieve good optical contact with the ATR crystal. Finally, DR-FTIR performed relatively well for most samples but was found to be more sensitive to moisture in the samples, resulting in noise in specific areas, and was less sensitive in bond vibrations related to Si.

Effects of fine grinding on mid-infrared spectroscopic analysis of plant leaf nutrient content

“…Studies that have compared NIR and MIR prediction models for leaves have achieved higher success on MIR spectra, furthering the case for the use of FT-MIR spectroscopy on plant material 11 , 31 . A study by Bekiaris et al determined that ATR and DRIFT FT-MIR techniques are well-suited to plant material analysis regarding spectral quality, but did not apply this to predictive models 32 . To the best of our knowledge, only one other study exists on the multiple nutrient analysis of leaves using FT-MIR 33 .…”

Prediction of biochemical methane potential of urban organic waste using Fourier transform mid-infrared photoacoustic spectroscopy and multivariate analysis

“…Furthermore, the development of different detectors and sampling techniques has led to easier sample preparation and increased recording accuracy, which have made MIR spectroscopy increasingly useful for the prediction of various sample properties. However, each detector offers different advantages for the various types of environmental samples (Bekiaris et al, 2020). Recently developed photoacoustic detectors use highly sensitive microphones to record the acoustic signal produced when infrared radiation interacts with the sample.…”