EPA Methods m 306a

Exhaust Gas Test Concentration. You must obtain a known concentration of each analyte from an independent source such as a specialty gas manufacturer, specialty chemical company, or chemical laboratory. You must also obtain the manufacturer's certification of traceability, uncertainty, and stability for the analyte concentration.

5.2 Tests for Other Waste Media. You must obtain the pure liquid components of each analyte from an independent manufacturer. The manufacturer must certify the purity, traceability, uncertainty, and shelf life of the pure liquid components. You must dilute the pure liquid components in the same type medium or matrix as the waste from the affected source.

5.3 Surrogate Analytes. If you demonstrate to the Administrator's satisfaction that a surrogate compound behaves as the analyte does, then you may use surrogate compounds for highly toxic or reactive compounds. A surrogate may be an isotope or compound that contains a unique element (e.g., chlorine) that is not present in the source or a derivation of the toxic or reactive compound if the derivative formation is part of the method's procedure. You may use laboratory experiments or literature data to show behavioral acceptability.

5.4 Isotopically-Labeled Materials. Isotope mixtures may contain the isotope and the natural analyte. The concentration of the isotopically-labeled analyte must be more than five times the concentration of the naturally-occurring analyte.