ASTM D4711-89(2017) pdf free.Standard Test Method for Sulfonic and Sulfuric Acids in Alkylbenzene Sulfonic Acids.
ASTM D4711 is applicable to the determination of sulfonic and sulfuric acids in branched and linear alkylbenzene sulfonic acids used as intermediates in synthetic detergents.
5. Interferences
5.) Strong acids, like nitric and hydrochloric, interfere, as do weak acids, such as carhoxylic acids. Small amounts of water originally present in the sample do not interfere in the determination. However, if as much as 5 % of water is present in the total solution (solvent plus sample). the end point becomes less sharp.
8. Standardization of 0.10 N Cyclohexylamine
8.1 All standardizations should he run in triplicate. This means separate weighings for solution preparations in 8.2.
8.2 Using an analytical balance, accurately weigh 0.10 to 0.12 g of sulfamic acid to the nearest 0. 1 rng into a 180 mL tall form beaker. Dissolve in 100 rnL of anhydrous methanol. Mix well.
8.3 Titrate with 0. 1N cyclohexylamine using the combination electrode on the automatic titrator until the complete development of a single break. Record the mL at the inflection point.
11.4 Repeatability(Single Analyst) – The standard deviation of results (each the average of duplicates) obtained by the same analyst on different days, has been estimated to be 0.16 % absolute at 14 degrees of freedom. Two such averages should be considered suspect (95% confidence level) if they differ b) more than 0.48% absolute.
11.6 Checking Limits for DiPicates-Report the active content of the sample to the nearest 0.01%.
12. Keywords
12.1 alkylbenzene sulfonic acid; sulfonic acid; sulfuric acid; titration
11.7 Bias-Since there is no accepted reference material suitable for determining the bias for the procedure in this test method, no statement on bias is being made.