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ANALYTICAL
CHEMISTRY,
VOL. 56, NO. 13, NOVEMBER 1984
is about 0.03 pg according to the specified conditions of sample size, irradiation time, and counting time described in this paper. The detection limit can be further improved with a larger quantity of sample or with longer irradiation and counting times. The molybdenum contents of most biological systems are in the ppm range. However, some biological systems may have much lower molybdenum contents. For example, scallop muscle has been reported to contain C0.1 ppm of molybdenum (13). The proposed extraction method should be sensitive enough to detect molybdenum at such low levels. Because biological samples generally have a relatively high iron content, spectral interference from the 142.5-keV y ray of 5QFemay create a problem for molybdenum determination. However, the extraction efficiency of iron with the dithiocarbamate solution at pH 1.4 is quite low (
