Determination of thallium in urine with Zeeman effect graphite furnace atomic absorption

Thallium is determined in urine with a simple dilution as the only sample pretreatment. Zeeman effect background correction provides adequate accommodation for non-atomic absorption such that sufficient diluted urine can be introduced into the furnace to achieve a detection limit of 0.5 ng/mL. Precision and accuracy were evaluated with Environmental Protection Agency water samples and in vitro spiked urine pools; precision of 15% at the 6 ng/mL level was observed. Diluted urine was used in calibration, with only 4 to 5% difference in slope observed within run among randomly selected urine specimens.