ASTM D5974 Method for Fatty and Rosin Acids in Tall Oil Fractionation Products
ASTM D5974 Standard Test Methods for Fatty and Rosin Acids in Tall Oil Fractionation Products by Capillary Gas Chromatography
AREA PERCENT METHOD
15. Apparatus - Same as apparatus described in Section 7.

16. Reagents and Materials
16.1 Purity of Reagents - See 4.2.1.

17. Procedure
17.1 Preparation of Test Sample - Weigh approximately 50 mg of sample into a suitable vial, and convert to methyl esters or substituted ammonium salts as described in Sections 4, 5, 6.

NOTE 12 - Rosin samples need to be freshly broken from a larger mass to ensure the results are not affected by air oxidation of the rosin.

18. Set-up of Gas Chromatograph
18.1 Set the GC conditions as described in 10.1.

19. Analysis
19.1 Inject 1 µL of the test sample prepared in 17.1.

20. Calculation
20.1 Sum all the areas of the individual peaks, exclusive of the solvent peak, to obtain the total peak area.

20.2 Calculate the relative percent of each fatty and rosin acid methyl ester present, uncorrected for the amount of polymeric materials present, as follows:
Fatty or rosin acid, % = (A x 100)/TA
A = peak area for fatty or rosin acid methyl ester being determined, and
TA = sum of areas of all fatty acid and rosin acid methyl ester peaks.

NOTE 13 - See Fig. 1 for chromatogram of a typical DTO.

21. Report
21.1 Report the area percent of the individual fatty and rosin acids to the nearest 0.1 %.

22. Precision and Bias
22.1 Area Percent Method - An interlaboratory study of the capillary GC determination of fatty and rosin acids in TOFA, DTO, and rosin was run in 1995 by nine laboratories. The design of the experiment, similar to that of Practice E691, and a within-between analysis of the data are given in an ASTM Research Report.
22.1.1 Test Result - The precision information given in Table 2 for fatty and rosin acids concentration of three naval stores products, is for the comparison of two test results.

22.1.2 Bias - Since there is no accepted reference material, method or laboratory suitable for determining the bias for the procedure in this test method for measuring component concentration, no statement on bias is being made.

23. Keywords
23.1 area percent; derivatization; fatty acids; gas chromatography; internal standard; rosin acids