Comparison of fast-atom bombardment, thermal ionization and inductively coupled plasma mass spectrometry for the measurement of 64Zn/67Zn stable isotopes in human nutrition studies.

Fast-atom bombardment, thermal ionization and inductively coupled plasma mass spectrometry are contrasted in comparative measurements of 64Zn/67Zn isotope ratios on samples isolated in the course of a human mineral-nutrition experiment. The data are evaluated with reference to the precision normally required in enriched stable-isotope mineral-nutrition studies, and the convenience of the mass spectrometric techniques is also compared.

Comparison of fast atom bombardment mass spectrometry and thermal ionization quadrupole mass spectrometry for the measurement of zinc absorption in human nutrition studies.

A method is described for the measurement of apparent zinc absorption in human nutrition studies. An enriched source of the stable isotope 67Zn was given to adult subjects together with a wheat cereal and the unabsorbed 67Zn measured in the feces. After drying, subsamples of the homogenized fecal material were ashed at 480 degrees C, purified for analysis by ion exchange chromatography, and the 64Zn/67Zn ratios determined by both fast atom bombardment mass spectrometry and thermal ionization quadrupole mass spectrometry. Good agreement was found between the two sets of results with mean precisions of approximately 0.5% for both techniques.

Iron and zinc absorption in human subjects from a mixed meal of extruded and nonextruded wheat bran and flour.

The effect of extrusion cooking of a bran-flour mixture on iron and zinc retention was measured in normal adults. The stable isotopes 58Fe (1.253 mg) and 67Zn (5.13 mg) were administered with 40 g nonextruded or extruded cereal with milk and isotopic retention was measured from fecal excretion over the next 4-7 d by neutron-activation analysis (Fe) and fast-atom-bombardment mass spectrometry (Zn). 58Fe retention was 15.1 +/- 2.4% (means +/- SEM) with the nonextruded meal and 16.5 +/- 2.7% with the extruded meal. 67Zn retention was 18.9 +/- 1.7% with the nonextruded meal and 18.3 +/- 1.5% with the extruded meal. Extrusion cooking had no effect on 58Fe or 67Zn retention.