ASTM D4423 Standard Test Method for Determination of Carbonyls in C4 Hydrocarbons
9. Calculation
9.1 Calculate as follows when the sample has no free acid or free base:
mg/Kg carbonyls (as acetaldehyde) = A x Nb x 44050/V x D
where:
A = alcoholic KOH titration, mL,
Nb = normality of KOH solution,
V = sample volume, mL, and
D = butadiene density at temperature T (found by using Table 1).
9.2 Calculate as follows when the sample has free acid:
mg/Kg carbonyls (as acetaldehyde) = (A - Bb) x Nb x 44050/V x D
where:
Bb = alcoholic KOH used for the sample blank, mL.
9.3 Calculate as follows when the sample has free base:
mg/Kg carbonyls (as acetaldehyde) = ((A x Nb) + (Ba x Na)) x 44050/V x D
where:
Na = normality of alcoholic HCl
Ba = alcoholic HCl used for the sample blank, mL
10. Precision and Bias
10.1 Precision - The precision of this test method as determined by statistical examination of interlaboratory results is as follows:
10.1.1 Repeatability - The difference between two test results obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, in normal and correct operation of the test method, exceed the following value in only one case in twenty, where X = the average of the two test results:
14 % of X
10.2 Reproducibility - The difference between two single and independent results obtained by different operators working in different laboratories on identical test material would, in the long run, in the normal and correct operation of the test method, exceed the following value in only one case in twenty, where X = average of two test results:
88 % of X
10.3 Bias - Since there is no accepted reference material for determining the bias for the procedure in this test method for measuring carbonyls, no statement on bias is being made.
11. Keywords
11.1 butadiene; C4 hydrocarbons; carbonyls; titration
