Measuring in situ CO2 and H2O in apatite via ATR-FTIR

Abstract

We present a new approach to determine in situ CO2 and H2O concentrations in apatite via attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). Absolute carbon and hydrogen measurements by nuclear reaction analysis (NRA) and elastic recoil detection (ERD) are used to calibrate ATR-FTIR spectra of CO2 and H2O in apatite. We show that CO2 and H2O contents in apatite can be determined via linear equations (r2 > 0.99) using the integrated area of CO2 and H2O IR absorption bands. The main benefits of this new approach are that ATR-FTIR analyses are non-destructive and can be conducted on polished sample material surfaces with a spatial resolution of ~ 35 μm. Furthermore, the wavenumber of the phosphate IR absorption band can be used to determine the crystallographic orientation of apatite, which allows for accurate quantification of CO2 and H2O in randomly orientated apatite grains. The limit of quantification of H2O in apatite is ~ 400 ppm and ~ 100 ppm for CO2. Via two examples, one from a carbonatite and one from a metasedimentary rock, we show that this new technique opens up new possibilities for determining volatile concentrations and behavior in a wide range of hydrothermal, igneous, and metamorphic systems.

Fabrication and Properties of the Montmorillonite/Nanobioglass Hybrid Reinforcement from Agroindustrial Waste for Bone Regeneration

“…Figure b shows the ATR-FTIR spectra of the MMT-NPs@MgNPs-BV in SBF solution after 2, 24, 72, and 168 h and apatite, where it was possible to identify the respective functional groups: (a) at 3688–3184 cm –1 : O–H resulting from W A ; (b) at 1646.2 cm –1 : bending vibrations of water molecules associated with structural water; (c) at 1448.2 cm –1 : stretching vibration of CO 3 2– groups within the crystal lattice; and (d) at 1038.2 cm –1 : symmetric vibration elongation of the PO 4 3– groups, confirming the chemical groups of apatite. It is noteworthy that no corresponding vibrations of MMT-NPs@MgNPs-BV were found, indicating a possible rapid biodegradation in contact with SBF, generating apatite and increasing bone regeneration.…”

“…34 Thus, as reflected by increasing diffraction intensities for the SBF assay ranging from 2 to 168 h, the apatite content grows at a slowly increasing degree of ordering and crystallinity comprising three stages of 2 h. SBF induction consists of the formation of the early apatite precursor, proliferation after 72 h in SBF, where there is rapid apatite growth of around ±80%, and maturation after 168 h, which consists of moderate structural ordering improving apatite crystallites. 35 Figure 7b shows the ATR-FTIR spectra of the MMT-NPs@ MgNPs-BV in SBF solution after 2, 24, 72, and 168 h and apatite, where it was possible to identify the respective functional groups: 36 (a) at 3688−3184 cm −1 : O−H resulting from W A ; (b) at 1646.2 cm −1 : bending vibrations of water molecules associated with structural water; (c) at 1448.2 cm −1 : stretching vibration of CO 3 2− groups within the crystal lattice; and (d) at 1038.2 cm −1 : symmetric vibration elongation of the PO 4…”

Comparative studies on chemically synthesized and biosynthesized zinc oxide nanoparticles using Desmodium sp. and their potential as UV filters

“…The scissoring bending mode of the water molecule is observed at 1636 cm -1 [23]. The absorption peaks at 1470 cm -1 and 1350 cm -1 are assigned to CO2 vibration [24]. Furthermore, the b-ZnO nanoparticles spectrum demonstrates absorption peaks at 3406 cm -1 , 1630 cm -1 , 1491cm -1 , 1384 cm -1 , 1260 cm -1 , 1040 cm -1 , 912 cm -1 , and 421 cm -1 .…”

CO2 diffusion in dry and hydrous leucititic melt

“…ATR-FTIR spectroscopy has already been used for the quantification of volatiles in silicate glasses (e.g. H 2 O: Lowenstern and Pitcher, 2013; CO 2 : Schanofski et al, 2023) but also for the quantification of H 2 O and CO 2 in apatite (Hammerli et al, 2021).…”