SEPARATION OF METALATED PETROPORPHYRIN MODELS USING MICELLAR ELECTROKINETIC CAPILLARY CHROMATOGRAPHY

Some percentage of the total metals found in crude oils is present as organometallic porphyrin complexes, and petroporphyrin separations are of interest in geochemical sciences, environmental monitoring, and pr ocess control. Various chromatographic techniques including GC, SFC, a nd HPLC have been used to resolve mixtures of petroporphyrins. In this work, a micellar electrokinetic capillary chromatographic method has been developed and applied to the separation of petroporphyrin model c ompounds, and using the MECC method Ni (II) and V(IV)O Etio I and Octa ethyl type porphyrins are completely resolved in 30 to 50 minutes. The MECC technique offers several advantages over a similar HPLC separati on including smaller mobile phase and sample volumes required, milder aqueous based solvents, and less expensive columns. Furthermore, the p eak capacity of the MECC separation is expected to be large because le ss hydrophobic, neutral species can migrate in the 6 to 30 minute sepa ration time window, suggesting that the technique when coupled to an I CP/MS detection system might prove extremely useful for metal speciati on studies.