FED-STD-791D
4.6 Crucible - 60 mL capacity, glass-fritted, medium porosity.
4.7 Oven suitable for drying filter discs at 110C.
5. MATERIALS
5.1 CAUTION: SOME MATERIALS ARE TOXIC AND HAZARDOUS. The
chemical materials listed in this section must be handled carefully. Federal Test Method
10000, Material Handling Safety Precautions, is a reference which lists all toxic and
hazardous materials cited in FTMS 791. The synonyms, life hazard, flammability,
handling and storage precautions, emergency treatment and measures, and spill practices
of each chemical are explained.
5.2 Saponification Mixture (lN) - Prepared by mixing 6.5 g potassium hydroxide
(ACS grade) [3,0,1] with 100 mL absolute n-butyl alcohol (ACS grade) [1,3,0] and
heating to dissolve the KOH. After the solution cools, the mixture is filtered through the
glass fiber filter paper.
5.3
Diphenylamine (1%) Solution - Prepared by dissolving 0.250 g
diphenylamine (ACS indicator grade) [3,1,0] in 25 mL sulfuric acid (sp gr 1.834) [3,0,2].
5.4 Toluene (ACS Reagent grade) [2,3,0].
NOTE 1:
Toluene is flammable and toxic. Avoid breathing vapors or contact with
skin.
6. PROCEDURE
6.1 Pipette 10 mL of sample into the reaction bottle and add 5 mL of toluene
followed by 10 mL of the saponification mixture.
Oral pipetting techniques should not be used because of the toxicity of the
NOTE 2:
substances involved. A pipetting bulb or assembly similar to one of those
described in 4.3 should be used.
6.2 Affix cap to the reaction bottle tightly and, after mixing the contents, place it
in an oven maintained at 110C for 4 h.
6.3 Remove the reaction bottle from the oven and allow it to cool to 25 3C.
6.4 Filter the contents of the reaction bottle through the 60-mL glass-fritted
crucible fitted with the glass fiber filter disc.
6.5 Wash the reaction bottle with 25 mL of toluene and transfer it to the
glass-fritted crucible.
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