Determination of trace gallium in serum by ICP-MS with a cobalt internal standard method.

A method for the determination of gallium at the μg dm-3 level by ICP-MS was studied as a basis for serum analysis. Coexisting NaCl (>0.01%) markedly reduces the ion intensities of 69Ga and 71Ga, whereas glucose (0.01-0.1%) does not interfere with the determination. Cobalt was found to be effective as an internal standard element, so as to correct for any matrix interference from NaCl. The method was applied to analyses of 1000- to 10- fold diluted serum samples spiked with Ga. The polyatomic ion (37Cl16O2) interference with the 69Ga intensity became significant when 10-fold diluted serum was analyzed. Therefore, a measurement of the ion intensity at 71Ga was preferred in order to obtain reliable results.