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arXiv · 2509.08633

Quantifying the liquid-liquid transition in cold water/glycerol mixtures by ih-RIDME

Sergei Kuzin·Maxim Yulikov
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Abstract

Water/glycerol mixtures are common for experiments with biomacromolecules at cryogenic temperatures due to their vitrification properties. Above the glass transition temperature, they undergo liquid-liquid phase separation. Using the novel EPR technique called intermolecular hyperfine Relaxation-Induced Dipolar Modulation Enhancement (ih-RIDME), we quantified the molar composition in frozen water/glycerol mixtures with one or the other component deuterated after the phase transition. Our experiments reveal nearly equal phase composition regardless of the proton/deuterium isotope balance. With the new ih-RIDME data, we can also revisit the already reported body of glass transition data for such mixtures and build a consistent picture for water/glycerol freezing and phase transitions. Our results also indicate that ih-RIDME has the potential for investigating the solvation shells of spin-labelled macromolecules.

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Sergei Kuzin, Maxim Yulikov. 2025-09-10. Quantifying the liquid-liquid transition in cold water/glycerol mixtures by ih-RIDME. https://arxiv.org/abs/2509.08633

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