7 determinations. CRER-1068 This was subsequently reduced to + 3.1% by the elimination of systematic errors in the method. Accuracy in the determination of barium is dependent on relative concentrations of the two elements as the results are obtained by difference (i.e. total count - strontium = barium). In these analyses the coefficient of variation amounted to + 13% and + 84 formilk and produce respectively. The egefficient of variation of the calcium results was + 2.0%, t DISCUSSION OF RESULTS | * 2 ee Tables IV and V give the results of analyses for calciun, strontium and barium in biological samples. The results are expressed per kilogram of produce, per gram of ash and as ratios of the elements, one to the other. In general, metabolic processes in the animal discriminate against strontium and barium, so that meat and milk contain much smaller concentrations of these elements than cereals and vegetables. As a consequence, strontium/calcium and barium/calcium ratios are also lower in animals and animal produce. Except in the case of cereals, ' the concentration of barium is generally below that of strontium, the average value for the ratio of barium/strontium being 0.36. It is noticeable that the results for barium are also more variable than those for snehaereae. strontium. Erratic behaviour of barium is not surprising inasmuch as it 1s chemically dissimilar to calcium and will not be regulated to the same extent by the mechanisms controlling calcium uptake.

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