BASE NUMBER BY POTENTIOMETRIC HCI TITRATION: ASTM D4739
(Equivalent Test Methods: IP 417, ISO 6619, and JIS K 2501)
EXPLANATION
Test Method D4739 was developed as an alternative for the base number portion of Test Method D664. Base numbers obtained by this test method may or may not be numerically the same as those obtained by the base number portion of Test Method D664.
TEST SUMMARY
The sample is dissolved in a mixture of toluene, isopropyl alcohol, chloroform, and a small amount of water and titrated potentiometrically with alcoholic hydrochloric acid solution. An end point is selected from a titration curve and used to calculate a base number.
A color indicator titration method is also available in the Test Method D974. The base numbers obtained by the potentiometric method may or may not be numerically the same as those obtained by Test Method D974. Potentiometric methods for base number are also available in Test Method D2896.
TEST PRECISION
Repeatability: 10.4 % of mean of two results
Reproducibility: 21.1 % of mean of two results
