ASTM D7371 test method for biodiesel content in diesel fuel oil
ASTM D7371 Standard Test Method for Determination of Biodiesel (Fatty Acid Methyl Esters) Content in Diesel Fuel Oil Using Mid Infrared Spectroscopy (FTIR-ATR-PLS Method)
9. Sampling and Sample Handling
9.1 General Requirements:
9.1.1 Fuel samples to be analyzed by this test method shall be sampled using procedures outlined in Practice D4057 or Practice D4177, where appropriate. Do not use "sampling by water displacement". FAME is more water-soluble than the hydrocarbon base in a biodiesel blend.
9.1.2 Protect samples from excessive temperatures prior to testing.
9.1.3 Do not test samples stored in leaky containers. Discard and obtain a new sample if leaks are detected.
9.2 Sample Handling During Analysis:
9.2.1 When analyzing samples using the FTIR, the sample temperature needs to be within the range of 15 to 27°C. Equilibrate all samples to the temperature of the laboratory (15 to 27°C) prior to analysis by this test method.
9.2.2 After analysis, if the sample is to be retained, reseal the container before storing.
10. Calibration and Qualification of the Apparatus
10.1 Before use, the instrument needs to be calibrated according to the procedure described in Annex A1. This calibration can be performed by the instrument manufacturer prior to delivery of the instrument to the end user. If, after maintenance, the instrument calibration is repeated, the qualification procedure is also repeated.
10.2 Before use, the instrument is qualified according to the procedure described in Annex A1. The qualification need only be carried out when the instrument is initially put into operation, recalibrated, or repaired.
11. Quality Control Checks
11.1 Confirm the in-statistical-control status of the test method each day it is used by measuring the biodiesel concentration of at least one quality control sample that is similar in composition and matrix to samples routinely analyzed. For details on quality control sample selection, preparation, testing, and control charting, refer to Practice D6299.
11.2 A system that is found to be out of statistical control cannot be used until the root cause(s) of out-of-control is identified and corrected.
11.3 If correction of out-of-control behavior requires repair to the instrument or recalibration of the instrument, the qualification of instrument performance described in A1.3 shall be performed before the system is used to measure the biodiesel content of samples.
