4.1 Knowledge of the concentration of benzene may be required for regulatory use, control of gasoline blending, and/or process optimizations.

1.1 This test method covers the determination of benzene and toluene in finished motor and aviation spark ignition fuels by gas chromatography. This test method has two procedures: Procedure A uses capillary column gas chromatography and Procedure B uses packed column gas chromatography. Procedures A and B have separate precisions.

1.2 The method working range for benzene is in the expected concentrations of: (1) Procedure A between 0.12 % and 5.2 % by volume and (2) Procedure B between 0.10 % and 5.0 % by volume.

1.3 The method working range for toluene is in the expected concentrations of: (1) Procedure A between 0.4 % and 19.7 % by volume, and (2) Procedure B between 2.0 % and 20.0 % by volume.

1.4 For benzene by Procedure A, the following oxygenated fuels are included in the working range: (1) ethanol up to 20 % by volume (E20); (2) methanol up to 10 % by volume (M10). Fuels M85 and E85 were excluded.

1.5 For benzene by Procedure B the following oxygenated fuels are included in the working range: (1) ethanol up to 20 % by volume (E20); (2) methanol up to 10 % by volume (M10). Fuels M85 and E85 were excluded.

1.6 For toluene by Procedure A the following oxygenated fuels were included in the working range: (1) ethanol up to 20 % by volume (E20); (2) M85 and E85.

1.7 For toluene by Procedure B the following oxygenated fuels are included in the working range: (1) ethanol up to 20 % by volume (E20); (2) M85 and E85.

1.8 Procedure A uses MIBK as the internal standard. Procedure B uses sec-butanol as the internal standard. The use of Procedure B for fuels containing blended butanols requires that sec-butanol be below the detection limit in the fuels as sec-butanol is an internal standard. For Procedure B, an alternative separation column set described in the annex (A2.3, Annex Approach B) uses MEK as the internal standard when butanols may be blended into gasolines.

1.9 This test method includes a relative bias section for benzene reporting based on Practice D6708 bias assessment between Test Method D3606 Procedure B and Test Method D5769. It is intended to allow Test Method D3606 Procedure B to be used as a possible alternative to Test Method D5769. The Practice D6708 derived benzene correlation equation is applicable for benzene measurements in the range from 0.04 % to 2.88 % by volume as reported by Test Method D3606 Procedure B. The correlation complies with EPA’s Performance Based Measurement System (PBMS).

1.10 Correlation equations are included in the relative bias section 13.2.1 of Procedure A to convert Procedure A to the Procedure B volume percent values for benzene and toluene. The correlations are applicable in the concentration ranges of 0.07 % to 5.96 % by volume for benzene and 0.36 % to 20.64 % by volume for toluene as reported by Procedure A. The bias corrected Procedure A to Procedure B result may be correlated further to benzene obtained by D5769 as described in 13.2.1.4(2) of Procedure A and 26.2.1 of Procedure B.

1.11 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.

1.12 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.13 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.