Because of their prevalence as solution vehicles, we will consider some
of the special qualities of syrups. A syrup is a concentrated or nearly
saturated solution of sucrose in water. A simple
syrup contains only sucrose and purified water (e.g. Syrup USP).
Syrups containing pleasantly flavored substances are known as flavoring
syrups (e.g. Cherry Syrup, Acacia Syrup, etc.). Medicinal
syrups are those to which therapeutic compounds have been added
(e.g. Guaifenesin Syrup).
Syrup, USP contains 850 gm sucrose and 450 ml of water in each liter
of syrup. Although very concentrated, the solution is not saturated. Since
1 gm sucrose dissolves in 0.5 ml water, only 425 ml of water would be required
to dissolve 850 gm sucrose. This slight excess of water enhances the syrup's
stability over a range of temperatures, permitting cold storage without
The high solubility of sucrose indicates a high degree of hydration
or hydrogen bonding between sucrose and water. This association limits
the further association between water and additional solutes. Hence, syrups
have a lower solvent power than water and "salting out" (see
Remington's for explanation) may be a problem.