In the GC-MS test for aromatics, why must the calibration curves be forced through the origin? All mass spectrometers will show some noise at a zero concentration level.

Calibration curves are not required to be forced through the origins. The reference in the regulation is a suggested method.(7/1/94)

This question and answer was posted at Consolidated List of Reformulated Gasoline and Anti-Dumping Questions and Answers: July 1, 1994 through November 10, 1997 (PDF)(333 pp, 18.17 MB, EPA420-R-03-009, July 2003, About PDF)