ASTM D7220 Standard Test Method for Sulfur in Automotive Fuels by Polarization X-ray Fluorescence Spectrometry
14. Report
14.1 For all samples analyzed, report the result calculated in 13.3. Report the result as the total sulfur content in mg/kg rounding to two significant figures up to 10 mg/kg and to three significant figures for results greater or equal 10 mg/kg using Practice E 29. State that the results were obtained in accordance with Test Method D7220.
15. Precision and Bias
15.1 The precision and bias of the test method, as determined by statistical examination of interlaboratory test results, was determined according to ISO 4259. One certified diesel sample, LGC 3023, was supplied as check sample. Another certified diesel sample, LGC 3021, was provided as a test sample (result not supplied) to determine the bias of the test method.
15.2 The precision of the test method is as follows:
15.2.1 Repeatability - The difference between successive test results obtained by the same operator with the same apparatus under constant operation conditions on identical test material would, in the long run, in the normal and correct operation of the test method, exceed the value:
where:
X = the mean sulfur content, only in one case in twenty. (See Table 3.)
15.2.2 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 value:
where:
X = the mean sulfur content, only in one case in twenty. (See Table 4.)
15.3 Bias - A certified diesel sample LGC 30218 was provided as a test sample (result not supplied). Subsequent statistical evaluation showed no apparent bias with the following results:
16. Keywords
16.1 automotive fuel; diesel; gasoline; petroleum; polarization; spectrometry; sulfur; X-ray