Determination of Thallium in Biological Samples by FDMS

Once the capacity of quantitative FD for alkali and alkaline earth cations was established the investigations were expanded to a wide variety of metals. One focal point in this analytical expansion of the method represents the toxic, heavy metal thallium. This metal exerts a pronounced toxic effect on mammals. Poisonings by thallium ions normally proceed very slowly they are accompanied by loss of hair, severe polyneuritic symptoms and tachycardia, and can culminate in paralysis of the central nervous system. Atomic absorption is a common spectroscopic method for the determination of thallium concentrations down to a few ppm . The direct determination of thallium from human urine reveals a limit of detection of approximately 30 ppb, whereas direct estimation from plasma and brain tissue is not successful without pretreatment. 

Since thallium naturally occurs as a mixture of two stable isotopes and since isotopically enriched thallium is commercially available, stable isotope dilution appears to be the method of choice for a mass spectrometric quantitation. 

In the determination of thallium by the isotope dilution technique three analyses are necessary. 

For a forensic study by FDMS a mouse is fed a portion containing thallium chloride (80 After the animal s death (5 h after application) the brain is 

Evaluation of the data from FDMS reveals a thallium concentration in the mouse brain of 4.0 + 0.3 mmol/kg fresh weight, which results in 0.8 0.06 / mol thallium in the complete brain. Thus, only 0.3 % of the total amount of thallium applied can be determined in the brain tissue. 

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