ASTM D6584 for Free and Total Glycerin in B-100 Biodiesel Methyl Esters
ASTM D6584 Test Method for Determination of Free and Total Glycerin in B-100 Biodiesel Methyl Esters By Gas Chromatography
6. Apparatus
6.1 Chromatographic System - See Practice D355 for specific designations and definitions.
6.1.1 Gas Chromatograph (GC) - the system must be capable of operating at the conditions given in Table 1.
6.1.2 Column, open tubular column with a 5 % phenylpoly-dimethylsiloxane bonded and cross linked phase internal coating. The column should have an upper temperature limit of at least 400°C. Columns, either 10 m or 15 m in length, with a 0.32 mm internal diameter, and a 0.1 µm film thickness have been found satisfactory. Any column with better or equivalent chromatographic efficiency and selectivity can be used. It is recommended that a 2 to 5 metre 0.53 mm high temperature guard column be installed from the injector to the analytical column. This allows the use of autoinjectors and also increases column life.
6.2 Electronic Data Acquisition System:
6.2.1 Integrator or Computer, capable of providing real time graphic and digital presentation of the chromatographic data is recommended for use. Peak areas and retention times shall be measured by computer or electronic integration.
6.2.2 This device must be capable of performing multilevel internal-standard-type calibrations and be able to calculate the correlation coefficient (r2) and internal standard calculations for each data set.
7. Reagents and Materials
7.1 Purity of Reagents - Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society where such specifications are available.4 Other grades may be used provided it is first ascertained that the reagent is of sufficient purity to permit its use without lessening the accuracy of the determination.
7.2 n-Heptane, reagent grade.
7.3 N-Methyl-N-trimethylsilyltrifluoroacetamide (MSTFA), reagent grade.
7.4 Pyridine, reagent grade.
7.5 Carrier Gas, hydrogen or helium of high purity. Additional purification is recommended by the use of molecular sieves or other suitable agents to remove water, oxygen, and hydrocarbons. Available pressure must be sufficient to ensure a constant carrier gas flow rate.
7.6 Microlitre Syringes, 100 µl and 250 µl capacity.
7.7 Screw Cap Vials, with polytetrafluoroethylene (PTFE) - faced septa, 10 mL capacity.
