Glycine Partitions into Halite during Crystallization in Ceres Simulant Brines
- 1Arizona State University
- 2California Institute of Technology
- 3University of Arizona
Abstract
Salts on Ceres may act as messengers of interior ocean chemistry, trapping organics and preserving parent brine compositions. However, relating organic detections to subsurface brine compositions requires quantifying how much organic material is retained in salt crystals relative to the parent solution, a ratio, to our knowledge, not yet measured for any organic–salt system relevant to ocean worlds. Here, we determine the apparent partition coefficient, α , for glycine (NH ₂ CH ₂ COOH), the simplest and most abundant amino acid in extraterrestrial materials, crystallized in halite (NaCl) from aqueous brine under evaporative conditions. Halite crystals were grown from brines containing 0–133 mM glycine and characterized using optical microscopy, Fourier transform infrared spectroscopy (FTIR), X-ray computed tomography (XCT), and gas chromatography with flame ionization detection (GC-FID). Reflected-light imaging and XCT reveal glycine incorporated as micrometer-scale inclusions rather than substituting into the crystal lattice, with crystal-to-crystal variability consistent with stochastic inclusion trapping. GC-FID yields a linear relationship between glycine concentration in the crystal and the parent brine, with α = 0.177 ± 0.019, meaning NaCl captured ∼18% of available glycine. Applied to Ceres, this implies that glycine concentrations in the subsurface reservoir can be at least 5 times higher than abundances in surface salt deposits and that individual salt grains may be heterogeneous even from a single source brine. This framework provides quantitative constraints for interpreting organic signatures observed in samples returned by a future Ceres mission, as recommended by the 2023–2032 Origins, Worlds, and Life Planetary Science and Astrobiology Decadal Survey.
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BibTeX
@article{reynoso2026glycine,
title = {{Glycine Partitions into Halite during Crystallization in Ceres Simulant Brines}},
author = {Lucas R. Reynoso and Maitrayee Bose and Julie C. Castillo-Rogez and Kirtland J. Robinson and John C. Bescup and Yang Liu and Jessica M. Weber and Robert A. Root},
journal = {The Planetary Science Journal},
year = {2026},
month = oct,
doi = {10.3847/psj/aea204},
url = {https://iopscience.iop.org/article/10.3847/PSJ/aea204},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Glycine Partitions into Halite during Crystallization in Ceres Simulant Brines
AU - Lucas R. Reynoso
AU - Maitrayee Bose
AU - Julie C. Castillo-Rogez
AU - Kirtland J. Robinson
AU - John C. Bescup
AU - Yang Liu
AU - Jessica M. Weber
AU - Robert A. Root
PY - 2026
DA - 2026/10/09
JO - The Planetary Science Journal
DO - 10.3847/psj/aea204
UR - https://iopscience.iop.org/article/10.3847/PSJ/aea204
AB - Salts on Ceres may act as messengers of interior ocean chemistry, trapping organics and preserving parent brine compositions. However, relating organic detections to subsurface brine compositions requires quantifying how much organic material is retained in salt crystals relative to the parent solution, a ratio, to our knowledge, not yet measured for any organic–salt system relevant to ocean worlds. Here, we determine the apparent partition coefficient, α , for glycine (NH ₂ CH ₂ COOH), the simplest and most abundant amino acid in extraterrestrial materials, crystallized in halite (NaCl) from aqueous brine under evaporative conditions. Halite crystals were grown from brines containing 0–133 mM glycine and characterized using optical microscopy, Fourier transform infrared spectroscopy (FTIR), X-ray computed tomography (XCT), and gas chromatography with flame ionization detection (GC-FID). Reflected-light imaging and XCT reveal glycine incorporated as micrometer-scale inclusions rather than substituting into the crystal lattice, with crystal-to-crystal variability consistent with stochastic inclusion trapping. GC-FID yields a linear relationship between glycine concentration in the crystal and the parent brine, with α = 0.177 ± 0.019, meaning NaCl captured ∼18% of available glycine. Applied to Ceres, this implies that glycine concentrations in the subsurface reservoir can be at least 5 times higher than abundances in surface salt deposits and that individual salt grains may be heterogeneous even from a single source brine. This framework provides quantitative constraints for interpreting organic signatures observed in samples returned by a future Ceres mission, as recommended by the 2023–2032 Origins, Worlds, and Life Planetary Science and Astrobiology Decadal Survey.
SN - 2632-3338
ER -