Analysis of 'APN' naphthenic acids by high temperature gas chromatoagraphy and high performance liquid chromatography

Examination by high temperature GC (HTGC) of the methyl esters of the so-called 'ARN' naphthenic acids from crude oils of North Sea UK, Norwegian Sea and West African oilfields revealed the distributions of resolved 4-8 ring C-80 tetra acids and trace amounts of other acids. Whilst all three oils contained apparently the same the proportions of each differed, possibly reflecting the growth tempe acids, ratures of the archaebacteria from which the acids are assumed to have originated. The structures of the 4, 5, 7 and 8 ring acids are tentatively assigned by comparison with the known 6 ring acid and related natural products and an HPLC method for the isolation of the individual acids is described. ESI-MS of individual acids isolated by preparative HPLC established the elution order of the 4-8 ring acids on the HPLC and HTGC systems and revealed the presence of previously unreported acids tentatively identified as C-81 and C-82 7 and 8 ring analogues.