1 research outputs found
Osmotic Virial Coefficients of Hydroxyethyl Starch from Aqueous Hydroxyethyl Starch–Sodium Chloride Vapor Pressure Osmometry
Hydroxyethyl starch (HES) is an important
industrial additive in
the paper, textile, food, and cosmetic industries and has been shown
to be an effective cryoprotectant for red blood cells; however, little
is known about its thermodynamic solution properties. In many applications,
in particular those in biology, HES is used in an aqueous solution
with sodium chloride (NaCl). The osmotic virial solution thermodynamics
approach accurately captures the dependence of osmolality on molality
for many types of solutes in aqueous systems, including electrolytes,
sugars, alcohols, proteins, and starches. Elliott et al. proposed
mixing rules for the osmotic virial equation to be used for osmolality
of multisolute aqueous solutions [Elliott, J. A. W.; et al. <i>J. Phys. Chem. B</i> <b>2007</b>, <i>111</i>, 1775–1785] and recently applied this approach to the fitting
of one set of aqueous HES–NaCl solution data reported by Jochem
and Körber [<i>Cryobiology</i> <b>1987</b>, <i>24</i>, 513–536], indicating that the HES osmotic virial
coefficients are dependent on HES-to-NaCl mass ratios. The current
study reports new aqueous HES–NaCl vapor pressure osmometry
data which are analyzed using the osmotic virial equation. HES modifications
were measured after dialysis (membrane cut off: 10 000 g/mol)
and freeze-drying using vapor pressure osmometry at different mass
ratios of HES to NaCl for HES up to 50% and NaCl up to 25% with three
different HES modifications (weight average molecular weights [g/mol]/degree
of substitution: 40 000/0.5; 200 000/0.5; 450 000/0.7).
Equations were then fit to the data to provide a model for HES osmotic
virial coefficient dependence on mass ratio of HES to NaCl. The osmolality
data of the three HES modifications were accurately described over
a broad range of HES-to-NaCl mass ratios using only four parameters,
illustrating the power of the osmotic virial approach in analyzing
complex data sets. As expected, the second osmotic virial coefficients
increase with molecular weight of the HES and increase with HES-to-NaCl
mass ratio