Abstract
We extract the porphyrins from urine, bile and feces by prolonged extraction with acetic acid-ether (Fink and Hoerburger, 1 Fikentscher, 2 Van den Bergh and others, 3 Brugsch 4 ). Uroporphyrin is lost but, according to Fischer and Zerweck, 5 this may be neglected except in extremely rare cases. The porphyrins are taken up by 5% HCl from the crude ether extract. Purification involves repetition of the transfer to ether and back to HCl. Phylloerythrin requires 10% HCl. Total porphyrin is estimated in 5% HCl by the intensity of the red fluorescence excited by ultraviolet light. Pure copro- or hematoporphyrin solution is used for standardization. Recovery of known amounts of pure porphyrins in 12 series of determinations averaged: coproporphyrin, 100%; hemato-porphyrin, 104%; mesoporphyrin, 97%; protoporphyrin, 103%.
Quantitative fractionation of the porphyrins is done by successive extractions of the purified ethereal solution with 1 volume 0.25% HCl to 3 volumes ether. Three such extractions remove all the coproporphyrin (and hemato-porphyrin which, however, does not occur naturally), 62% of the mesoporphyrin, 10% of the protoporphyrin, and about 49% of the deuteroporphyrin.
These results on pure porphyrins apply also to mixtures. Quantitative estimates of copro- and protoporphyrin in known mixtures are precise within ±3% of the total; similar mixtures of copro- or proto- with mesoporphyrin were separated with an error no greater than ±6%.
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