14.1 Confirm the performance of the instrument or the procedure each day it is in use by analyzing a QC sample that is representative of samples typically analyzed. Quality control frequency should be increased if a large number of samples are routinely analyzed. If the analysis is shown to be in statistical control, QC frequency may be reduced. Analysis of result(s) from these QC samples may be performed using control chart techniques4 or other statistical techniques. If the QC sample result determined causes the laboratory to be in an out-of-control situation, such as exceeding the laboratory's control limits, investigate and take corrective action to bring the test back into control before proceeding. An ample supply of QC sample material shall be available for the intended period of use and shall be homogeneous and stable under the anticipated storage conditions. Prior to monitoring the measurement process, the user of the method needs to determine the average value and control limits of the QC sample. The QC sample precision shall be checked against the ASTM method precision to ensure data quality.
15. Calculation
15.1 Calculate the water concentration in mg/kg or µL/mL of the sample as follows:
15.3 Use the following equations for calculating the water content of the sample in units of volume % from mass %, or of mass % from volume %.
water, volume % = water, mass % / density of product at room temperature (density may be measured using Test Methods D 1298 or D 4052)
water, mass % = water, volume % 3 density of product at room temperature (density may be measured using Test Methods D 1298 or D 4052)
16. Report
16.1 Report the water concentration to the nearest whole (mg/kg), nearest 0.01 mass %, nearest whole µL/mL, or nearest 0.01 volume %.
16.2 Report the water concentration as obtained by Test Method D 6304, Procedure A, Procedure B, or Procedure C.
17. Precision and Bias
17.1 The precision of this test method as determined by the statistical examination of interlaboratory test results is as follows:
17.1.1 Repeatability - The difference between successive results obtained 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 values only in 1 case in 20.
17.1.2 Reproducibility - The difference between 2 single and independent results obtained by different operators working in different laboratories on identical test materials would, in the long run, exceed the following values in only 1 case in 20.
17.2 Bias - This test method has no bias since the coulometric determination can be defined only in terms of this test method.
18. Keywords
18.1 coulometric titration; Karl Fischer titration; water