Handbook of Solvents - George Wypych - ChemTech - Ventech!

15
Methods of Solvent Detection
and Testing
15.1 STANDARD METHODS OF SOLVENT ANALYSIS
George Wypych
ChemTec Laboratories, Inc., Toronto, Canada
This section includes information on solvent analysis based on methods included in national
and international standards. ASTM standard methods are emphasized because they contain
more methods on solvent testing than any other set of methods available. ISO standards are
also covered in full detail because they are used in practical applications and are a basis for
preparation of national standards. References to other national standards are also given including
Australian (AS), Australian/New Zealand (AS/NZS), (British (BS), Canadian
(CAN/CGSB), German (DIN), Japanese (JIS), and Finish (SFS). The same number is given
in references to all national and international standards for the same solvent property to facilitate
searching and referencing. Methods of analysis are grouped by subject in alphabetical
order.
15.1.1 ALKALINITY AND ACIDITY
Amine acid acceptance by halogenated solvents is the degree to which an amine is capable
of absorbing or neutralizing acid present from an external source or generated by the
solvent. 1 This method is useful for comparing the effect of an amine with other
acid-accepting compounds. The test is performed by the titration of an alkaline water
extract from the solvent with 0.2 N hydrochloric acid to pH = 3.9 as detected by pH
electrode.
The alkalinity of acetone is determined by a titration with 0.05 N H2SO4 in the presence
of methyl red indicator. 2 The test method provides a measure of acetone alkalinity calculated
as ammonia.
The acidity of halogenated solvents can be determined by titration with 0.01 N sodium
hydroxide in the presence of a 0.1% solution of bromophenyl blue indicator. 3 Similar to the
determination of alkalinity, 1 acidity is determined in water extract. The determination can
also be done directly in solvent but the solution of sodium hydroxide should be prepared in
methanol. A third option is to determine acidity by a pH-metric titration of a water extract.
Prior to determination, the pH of solvent is measured. If the pH is above 7, then an alkalinity
measurement is done by the above method. 1 If the pH is below 7, acidity is determined by
this method. 3 The method is used to establish purchasing and manufacturing specifications
and control the quality of solvents.