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Porphyrins in crude oil are large, complex molecules derived primarily from chlorophyll and related compounds. They are found in virtually all oils and rock extracts, with the exception of condensates that have lost their heavy ends. Porphyrins are separated by HPLC and can be analyzed by several different methods.

Porphyrins in crude oil are large, complex molecules derived primarily from [[chlorophyll]] and related compounds. They are found in virtually all oils and rock extracts, with the exception of [[condensate]]s that have lost their heavy ends. Porphyrins are separated by HPLC and can be analyzed by several different methods.

==Example==

==Example==