ASTM D4864 Test Method for Determination of Traces of Methanol in Propylene Concentrates by Gas Chromatography
13. Calculation
13.1 Calculate the methanol content of the propylene concentrate using the following equation:
Methanol, mg/kg (ppm mass) = (A·F·Fx·W)/G
where:
A = area of methanol peak,
F = methanol response factor for the sample size used (Eq 1),
Fx = methanol extraction factor (Eq 3),
W = mass of water used in the extraction, g, and
G = mass of propylene concentrate extracted, g.
14. Precision and Bias
14.1 Precision - The precision of this test method as determined by the statistical examination of interlaboratory test results is as follows:
14.1.1 Repeatability - The difference between successive results by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, in the normal and correct operation of the test method exceed the following value only in 1 case in 20:
Repeatability = The maximum allowable ratio of the larger to the smaller result is 2.4.
14.1.2 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, exceed the following values only in 1 case in 20:
Reproducibility = The maximum allowable ratio of the larger to the smaller is 8.0.
14.2 Bias - Since there is no accepted reference material suitable for determining the bias for this procedure for measuring methanol, the bias is not available for this test method.
15. Keywords
15.1 gas chromatography; methanol; propylene
