Spectroscopy study of freezing-induced acidity change of buffers in the presence of sugars.

                               Susrisweta Behera^1, Dominik Heger^1*

   ^1 Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 5, CZ62500 Brno,
                                              Czechia

                                       susrisweta@gmail.com

Freezing of aqueous buffer solutions leads to the formation of freeze-concentrated solutions (FCS),
which can expose the local environment (bio)chemicals to extreme conditions such as low
temperatures, concentration increase^[1], etc. These conditions alter the proton concentration and
acidity, leading to compound degradation, including protein aggregation^[2]. To overcome this
problem, the use of buffers containing sugars has been proposed as a potential solution to reduce
the acidity changes induced by freezing^[3]. Thus, in this study, we aimed to investigate the
effects of different sugars, namely monosaccharides (glucose), disaccharides (sucrose and lactose),
and sugar alcohols (mannitol), on the acidity of a citrate buffer system using the molecular probe
method^[4]. Our results demonstrate that the addition of sugars to the buffer system can
significantly mitigate the extent of acidity change induced by freezing, with sucrose exhibiting
the greatest efficacy in this regard followed by mannitol and lactose. These findings are of great
significance in the fields of biotechnology and medicine, where maintaining sample stability is
critical for accurate and reliable analysis.

Keywords: Freezing, Freeze concentrated solution, Freeze-induced acidity change, Buffers


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