A new apparatus and the relevant method to retrieve IR spectra of solutes from the corresponding aqueous solutions

Xiaohua Zhang; Lei Ni; Anqi He; Limin Yang; Isao Noda; Yukihiro Ozaki; Ran Guo; Yizhuang Xu

doi:10.1016/j.saa.2023.122598

A new apparatus and the relevant method to retrieve IR spectra of solutes from the corresponding aqueous solutions

Spectrochim Acta A Mol Biomol Spectrosc. 2023 Aug 5:296:122598. doi: 10.1016/j.saa.2023.122598. Epub 2023 Mar 24.

Authors

Xiaohua Zhang¹, Lei Ni¹, Anqi He¹, Limin Yang², Isao Noda³, Yukihiro Ozaki⁴, Ran Guo⁵, Yizhuang Xu⁶

Affiliations

¹ Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, PR China.
² State Key Laboratory of Nuclear Physics and Technology, Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871, PR China. Electronic address: yanglm@pku.edu.cn.
³ Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, PR China; Department of Materials Science and Engineering, University of Delaware, Newark, Delaware 19716, United States.
⁴ Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, PR China; School of Biological and Environmental Sciences, Kwansei Gakuin University, Sanda, Hyogo 669 - 1330, Japan.
⁵ PerkinElmer Inc., Jiuxianqiao Road, 14, Chaoyang District, Beijing 100015, PR China.
⁶ Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, PR China. Electronic address: xyz@pku.edu.cn.

PMID: 36996520
DOI: 10.1016/j.saa.2023.122598

Abstract

An apparatus and relevant approach to obtaining IR spectra of solutes from the corresponding aqueous solution were developed. In the experiment, aqueous solutions were converted into aerosols using an ultrasonic or a pneumatic device. Subsequently, water in the nebulized solution is completely gasified under a high-speed flow and low vacuum environment. Via this process, the aqueous solution changes into a mixture of a solute or solutes and gaseous water, whose single-beam IR spectra are collected. Then, the newly developed RMF (retrieving moisture-free IR spectrum) method and the relevant approach described in our recent papers have been adopted to treat the resultant single-beam sample spectrum. As a result, the spectral contribution of the vibrational-rotational peaks of gaseous water can be removed or significantly attenuated, and IR spectra of solutes can be obtained. The approach shows an obvious advantage in retrieving the IR spectrum of volatile solutes from its aqueous solution. This capability is showcased by obtaining IR spectra of isopropanol and ethyl acetate successfully. IR spectra of these compounds can be retrieved even if the concentration of the solute is below 10 wt%. Moreover, atomization via ultrasonic/pneumatic methods offers a mild way to gasify solutes whose boiling points are remarkably higher than that of water. This advantage is manifested by acquiring IR spectra of 1-butanol and 1,2-propanediol in the gaseous phase under ambient conditions.

Keywords: 2D-COS; Aqueous solution; FTIR; Water vapor.