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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 [[condensate]]s 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==