ATR-FTIR and XRD quantification of solid mixtures using the asymptotic constant ratio (ACR) methods. Application to geological samples of sodium and potassium feldspars

Antonio Doménech-Carbó; Francisco Bosch-Reig; Noemí Montoya

doi:10.1016/j.saa.2020.118328

ATR-FTIR and XRD quantification of solid mixtures using the asymptotic constant ratio (ACR) methods. Application to geological samples of sodium and potassium feldspars

Spectrochim Acta A Mol Biomol Spectrosc. 2020 Aug 5:236:118328. doi: 10.1016/j.saa.2020.118328. Epub 2020 Apr 3.

Authors

Antonio Doménech-Carbó¹, Francisco Bosch-Reig², Noemí Montoya²

Affiliations

¹ Departament de Química Analítica, Universitat de València, Dr. Moliner 50, 46100 Burjassot, Valencia, Spain. Electronic address: antonio.domenech@uv.es.
² Departament de Química Analítica, Universitat de València, Dr. Moliner 50, 46100 Burjassot, Valencia, Spain.

PMID: 32299036
DOI: 10.1016/j.saa.2020.118328

Abstract

Two asymptotic constant ratio methods applied to the quantification of individual components of solid samples using attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray diffraction (XRD) are described. The methods involve the measurement of the peak current/peak areas of selected signals (diffraction peaks in XRD and absorption bands in ATR-FTIR) relative to the signal of standard added in constant proportion to the sample and the sample enriched with the analyte following the usual standard additions methodology. The proposed method compensates the absorption effects appearing in XRD and the presence of overlapping absorption bands of interferents by means of an asymptotic representation thus avoiding the need of the knowledge of the absorption parameters of the matrix and analytes. The method was tested for mixtures of different metal oxides and sodium and potassium feldspars with satisfactory results.

Keywords: ATR-FTIR; Constant ratio asymptotic; Feldspars; Quantification; XRD.