Iron acetylacetonate, mass

A mass spectrometric method was developed for quantifying stable iron isotope tracers present in blood and fecal samples. Volatile Iron acetylacetonate [Fe(6511702)3] was prepared. 

In thermal ionization mass spectrometry (TI-MS), solid, inorganic compounds may be volatilized from a heated surface. TI-MS is the most precise method for the measurement of isotopic ratios of minerals and has been used to analyze 58pe in fecal samples collected from a human study (H). The major drawbacks of this technique are the costly instrument and the slow sample through-put. Conventional mass spectrometry produces ions by electron bombardment of the vapor of volatile compoimds. This is called electron-impact ionization mass spectrometry (EI-MS). Analysis of iron by EI-MS requires derivitization to volatile forms before introduction into the mass spectrometer. A method has been developed for the synthesis of volatile iron-acetylacetone chelates from iron in blood serxm (1 ). A tetraphenylporphyrin chelate has also been synthesized and used in an absorption study in which 54pe and 57pe were given orally (16). 

The aim of this study was to further explore the potential and limitations of using stable iron isotopes as tracers and EI-MS in absorption studies. Procedures were developed for preparing iron acetylacetonate from both blood and fecal samples for mass spectrometric analysis. The precision and accuracy of ion abundance measurements were evaluated. In vivo use of stable iron isotope tracers was tested with a human study in which 54pe and 57pe were given orally and absorption was estimated with the fecal monitoring and hemoglobin incorporation methods. 

Figure 1. Mass spectrum of iron acetylacetonate Fe(C5H702)3 prepared from a unenriched iron standard. Spectra obtained for unenriched blood and fecal samples showed a similar pattern.

Polyethylene and polypropylene blended with iron carboxylate complexes, for example, acetylacetonate (FeAcAc) and stearates (FeSt), and irradiated by UV light under accelerated aging conditions were shown to act as effective phtoactivators giving rise to rapid photoxidation as shown from the rapid rate of carbonyl formation without any induction period (see Fig. 16.4a for FeAcAc in HDPE) and with a reduction in molar mass (see Fig. 16.2a for FeSt in LDPE). However, these complexes have been shown to cause considerable oxidation to both PE and PP during processing reflected in a sharp increase in the polymer s melt flow index (reflecting chain scission and drop in molar mass) (Fig 16.4b) and act, therefore, as thermal prooxidants and cannot be used without the use of additional antioxidants in the system [2,3,17-19,48,49]. 

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