ISTItODUCTION
In recent years the physiological effects produced by radioactive substances have necessitated an intensified study of the metabolism of a wide range of elements in man. The burdens of strontium* and radium" carried by human tissues have been of special interest because of the hazard to health occasioned by the long-livccl isotopes and daughters of these elements. Whilst the radiological danger to health involved in the assimilation of trace amounts of barium is probably small, the close similarit> of this clement with both strontium anti radium made it clcsirnl~lc to study its distribution in the body. The spectrographic method outlined below was clcvclopccl in response to a demand for a rapid method fog the determination of barium in bone ash.
A spectrographic method had already been clevelopecl for the detcrminntion of total strontium in bonc3 and the possibilitv of its use for the determination of barium wits investigated.
In this method the sample of bone ash was ggouncl wit11 nnhyclrous copper sulphatc and graphite and pellets of the mixture burnt in a d.c. arc. It was found that this technique was not applicable to the determination of barium because the most sensitive barium lines were overlain with a band system and in any cast the sensitivity was not sufficient to cover the desired concentration rang2 of o-25 p.p.m. Espcrimcntal work was directed therefore towards developing a m&hod with improved sensitivity and in particular to the reduction of the intensity of the intcrfering band system associated with the most sensitive barium lint at 4554.0 A.
. ESI'ERIM@NTAI.
Initial attempts were made to improve sensitivity by using alkali fluorides as fluxes in the hope that barium would distii selectively. This approach was not successful. The cathode layer tcchn ique4 anti intermittent a.c. arc m&hods applied clircctly to bone ash, showed no impr,ovement. An attempt was then made to obtain adequate sensitivity by using copper sulphate and graphite as in the method for the determination of strontium" but to reduce the ratio of spectrographic buffer to sample and to increase the weight of the pellet burnt in the arc to 30 mg. This method gave improved, although inadequate, sensitivity for barium and it was still necessary to suppress C.