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Journal Article

# The Osmotic Potential of Polyethylene Glycol 6000

Burlyn E. Michel and Merrill R. Kaufmann
Plant Physiology
Vol. 51, No. 5 (May, 1973), pp. 914-916
Stable URL: http://www.jstor.org/stable/4263240
Page Count: 3

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Osmotic potential ($\psi _{s}$) of aqueous solutions of polyethylene glycol 6000 (PEG-6000) was curvilinearly related to concentration. At given concentrations, $\psi _{s}$ increased linearly with temperature. The effects of concentration and temperature on $\psi _{s}$ of PEG-6000 solutions differ from those for most salts and sugars and apparently are related to structural changes in the PEG polymer. Measurements of $\psi _{s}$ with thermocouple psychrometers are more negative than those with a vapor pressure osmometer, with the psychrometer probably giving the more nearly correct $\psi _{s}$ for bulk solutions. An empirical equation permits calculation of $\psi _{s}$ from known concentrations of PEG-6000 over a temperature range of 15 to 35 C. Viscometery and gravimetric analysis are convenient methods by which the concentrations of PEG-6000 solutions may be measured.