Document Type

Dissertation

Publication Date

Spring 5-19-1966

Abstract

The unsatisfactory state of current methods for the measurement of iron in serum or plasma is revealed by a review of recent literature. This was confirmed by a critical examination of three representative and widely used colorimetric iron procedures. The deficiencies of these methods, namely poor reproducibility and inadequate recovery of iron added to serum, were found to be compounded to a degree of unacceptability by the very marked inhibit ion of color production caused by the presence in serum of the powerful iron chelator desferrioxamine. Attempts to improve the best of these colorimetric procedures were only partially successful. Atomic absorption spectrophotometry was investigated as a means of quantitating serum iron, with the view of developing a procedure which not only fulfilled the usual requirements of reproducibility, and specificity, but in addition was unaffected by the presence in serum of a physiological concentration of desferrioxamine, a compound commonly used for the treatment of iron poisoning. Conventional methodology for this type of analysis was found to be unsatisfactory, due to the high degree of sensitivity required eliminating the possibility of sample dilution. Recorder curve integration was examined and adopted as the means of quantitation. Marked inhibition of absorption due to phosphate was found. This was eliminated by the incorporation into standards of iron free protein, which while itself inhibiting absorption caused no cumulative effect with other anions. The method developed gave 95% confidence limits of 6.88% with a mean recovery of added iron of 91.89%. Using this means of quantitation, methods were devised for the measurement of the distribution of iron in serum in the presence of desferrioxamine. These revealed that iron is bound by this chelator as a logarithmic function of chelator concentration. In vivo studies demonstrated that desferrioxamine is rapidly metabolized, while the iron complex of this chelator is not metabolized, but is rapidly cleared from the circulation by the kidneys.

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