This contais 54 components, incorporates all phenols, for fast preparation and calibration, incorporates 'additional' extractable method 625 compounds. GC-MS method applicable to analysis of organic compounds in water and soil.

Some of the target compounds in method 625 are subject to thermal or chemical degradation and consequent unpredictable chromatographic performance. hexachlorocyclopentadiene can decompose at the GC inlet. N-nitrosodimethylamine is difficult to separate from the solvent; also suggests that the analyst follow method 607 to identify this analyte. Some phenolic compounds in the target list, including chlorinated, methylated, and nitro-substituted phenols, are susceptible to adsorption and/or thermal degradation at the GC inlet. In addition, peak tailing can be a problem with phenols.

Diphenylamine is included, rather than N-nitrosodiphenylamine, in the MegaMix formulation because N-nitrosodiphenylamine decomposes to diphenylamine at the GC inlet.

Additional compounds in method 625 (listed compound N-nitrosodiphenylamine decomposes to MegaMix component diphenylamine). The six other additional compounds are components in othe reference mixes used for method 625: benzidine is included is β-BHC, δ-BHC, endosulfan I, endosulfan II, endrin.