New applications of near-infrared spectrometry

Mauricio de Silya Baptista, Marquette University


Near-infrared (near-IR) spectrometry has evolved considerably in recent years, becoming an important tool to several fields of science and technology, including chemistry, physics, medicine, polymer and food sciences. The reasons for this increased interest are several including its wide applicability, the possibility of in situ applications, and the availability of powerful multivariate statistical treatments. It is our primary goal in this research project to develop new instruments for the near-IR region. New methods that are sensitive to either the concentration of chemicals or the physical-chemical properties of the solutions will then be developed using these instruments. The first part of our research focused on the development of a near-IR thermal lens spectrophotometer. This method has applicability and selectivity that are similar to other near-IR spectrometric techniques, but has superior sensitivity. The performance of the near-IR thermal lens spectrophotometer was tested in several assays of chemical and isotopic purity of solvents and in the determination of nucleotides. The second part of our research focused on the applications of the near-IR thermal lens technique to the determination of the structure of water solutions. A new method that is based on the measurements of the thermo-optical properties of the water solutions as a function of the temperature and the concentration of solute was developed. Interestingly, it was shown that by using this technique, it is possible to characterize the effects of structure breaker and former agents as well as of surfactants on the structure of water. This technique was also applied to the characterization of the structure of reversed micelles and microemulsions. The last part of our research has focused on the flow injection analysis (FIA) technique. FIA was used for the determination of molecular association constants in micellar and cyclodextrin solutions. A new FIA universal detector was also developed. It was based on a near-IR spectrophotometer that has an acoustic optic tunable filter (AOTF). The performance of this detector was evaluated by using it in the determination of trace amounts of water in chloroform, and in the determination of trace amounts of water and benzene in ethanol.

Recommended Citation

Baptista, Mauricio de Silya, "New applications of near-infrared spectrometry" (1996). Dissertations (1962 - 2010) Access via Proquest Digital Dissertations. AAI9719075.