Separation and spectrodensitometric quantitation of porphyrin esters on thin-layer chromatograms

Use of eluent containing surfactant for the liquid chromatographic analysis of porphyrins by direct serum injection

A gradient elution reversed-phase high-performance liquid chromatographic method was developed for the direct serum injection analysis of porphyrins based on the use of eluent containing an anionic surfactant (sodium dodecyl sulfate) at a concentration below the critical micelle concentration to elute the serum proteins at the column void volume. Separation and detection performances were tested with a mixture of porphyrin standards containing uro-, heptacarboxylic-, hexacarboxylic-, pentacarboxylic-, copro-, zinc proto- and mesoporphyrin in a model serum consisting of 50 mg/ml bovine serum albumin. Average limit of detection is 0.06 pmol with a 10-microliter injection volume using fluorimetric excitation at the Soret band of porphyrins. The utility of this method for the direct serum injection analysis of porphyrins in human serum was evaluated by investigating serum samples from individuals suffering from iron-deficiency anemia and breast cancer.

High-performance liquid chromatographic determination of zinc protoporphyrin and porphyrin carboxylic acids in urine

A method for the reversed-phase high-performance liquid chromatographic separation of zinc protoporphyrin and porphyrin carboxylic acids with fluorescence detection and its application are described. A mu Bondapak C18 column was employed for all the experiments in this study. The method required a pretreatment of the column with a two-component mobile phase containing 0.1 M NaH2PO4 in acetonitrile (28:15, v/v, pH 5.3) for 10 min prior to sample injection. Separation was achieved isocratically by increasing the concentration of acetonitrile in the mobile phase (0.1 M NaH2PO4:acetonitrile, 18:130, v/v, pH 5.3) 4 min after injection to complete the elution. The flow rates and the period of pretreatment of the column were studied to optimize the separation. The method was applied to determining zinc protoporphyrin and porphyrin carboxylic acids of heme biosynthesis in urine.

Planar chromatographic techniques in biomedicine: current status

In planar chromatography (PLC), the solvent flows through a layer either by means of capillary forces [conventional thin-layer chromatography (TLC)] or by a forced-flow system (over-pressured layer chromatography). Phases and instrumentation currently available are briefly examined. The main applications in biomedicine are reviewed. Although silica gel TLC plates still predominate, interest in other phases is increasing. Unique detection features such as immunostaining are emphasized. Although gas chromatography and high-performance liquid chromatography have superseded TLC in the analysis of carbohydrates, amino acids and indole derivatives, interest in PLC continues to be high in lipid analysis.

Reverse-phase purification and silica gel thin-layer chromatography of porphyrin carboxylic acids

Thin-layer chromatography on silica gel 60 plates in the solvent N,N-dimethylformamide/methanol/ethylene glycol/glacial acetic acid/1-chlorobutane/chloroform (4/35/6/0.4/18/20 by volume) separates porphyrin carboxylic acids by the number of free carboxyl groups. Coproporphyrins I and III and isocoproporphyrin are separated in 30 min, other porphyrins in 15 min. The N,N-dimethylformamide and acetic acid in the solvent strongly increase porphyrin fluorescence on the plates. Fading and diffusion of the fluorescent patterns is prevented by storage of the plates in the cold and dark without oxygen and with desiccant. In a preliminary step, porphyrins are purified in high yields, concentrated, and deacidified rapidly (2 min) by reverse-phase chromatography on cartridges containing a C18 spacer or on Amberlite XAD-2 columns. The methods are applied to urines of porphyria patients and for following porphyrin ester hydrolysis.