Handbook of Solvents - George Wypych - ChemTech - Ventech!

15.1 Standard methods of solvent analysis 1067
underlining principle of the method is that organic chemicals bind with the surfaces of
solids through chemical and physical interactions. However, the sorption coefficient is
based on organic carbon content which does not apply to all solvents or all soils.
The sorption coefficient of a particular solvent is measured by equilibrating its aqueous
solution, containing a realistic concentration similar to that found in the environment,
with a known quantity of soil or sediment. After equilibrium is reached, the concentration of
solvent in the water and the soil is measured by a suitable analytical technique. The sorption
constants for all solids tested are averaged and reported as a single value. The standard does
not define the actual method of determining the concentrations but strategy that should be
followed. The data are useful in predicting the migration of chemicals in soil, in estimating
their volatility from water and soil, determining their concentration in water, and their propensity
to leach through the soil profile.
15.1.30 SOLVENT EXTRACTION
Often materials must be extracted from a compounded product to perform testing. Extracted
material must then be recovered from solution without degradation to be subjected to
testing. The method discussed here was developed as means of recovering asphalt from
pavement samples. 109 The solution of extracted asphalt in solvent is distilled by rotating the
distillation flask of a rotary evaporator in a heated oil bath. The distillation is carried out under
partial pressure in the presence of nitrogen to prevent degradation. The asphalt
recovered by this method can be tested in the same manner as were the original asphalt samples.
15.1.31 SPECIFICATIONS
Standard specifications are designed to set criteria for commercial solvents which can be
used to determine the compliance of a solvent sample. Because applications of solvents differ
very widely, the selected criteria are also different for different groups of solvents. Table
15.1.1 is a compiled list of parameters all of which can be found in solvent specifications.
The most common parameters used to characterize solvent include acidity, appearance,
color, concentration of main component, distillation range, dry point, initial boiling point,
and specific gravity. The methods of determining these parameters are found in this chapter.
The list of references includes information on specifications for various solvents.
Solvents in this list are arranged into groups: alcohols, 110-120 aromatic hydrocarbons, 121-128
other hydrocarbons, 129-132 ketones, 133-138 esters, 139-145 glycol, 146 and chlorine-containing solvents.
147-152
15.1.32 SUSTAINED BURNING
The sustained burning test was originally developed for British Standard BS-3900 and
adapted by ASTM. 153 The purpose of the test is to determine the sustained burning
characteristics of solvents by direct experiment rather than by deducing characteristics from
flash point data. Mixtures of some flammable liquids (e.g., alcohol and water) are classified
as flammable based on the closed-cup flash point method. Some mixtures may be classed as
flammable even though they do not sustain burning. The test is performed in a block of
aluminum with a concave depression called a well. The liquid under test is heated to a temperature
of 49 o C and a flame is passed over the well and held in position for 15 s. The
specimen is observed to determine if it can sustain burning.