Beryllium determination in urine at nanogram level for biomonitoring purpose

Beryllium exposure is known to seriously affect health, and even very low levels of exposure may be toxic. It is therefore essential that biological or air-monitoring strategies adopted in the workplace are reliable and accurate over a range of exposure levels. A new high-sensitivity and reproducible method for determining Be levels in human urine is presented. The method was tested on both workers and non-occupationally exposed individuals with the eventual aim of establishing reference levels for both populations.
A chelate of beryllium acetylacetonate formed from beryllium (II) in human urine was preconcentrated on a Sep-Pak C18 cartridge and eluted with methanol. After drying the eluate, the residue was solubilized in nitric acid and analyzed by Atomic Absorption Spectrometry and/or Inductively Coupled Plasma Mass Spectrometry.
The new method is 4 to 100 times more sensitive than other routinely-used methods. The method was validated using the concordance correlation coefficient test for 10 to 100 ng/L Be. The influence of creatinine concentration, urine pH, interfering compounds and freeze-thaw cycles was evaluated. The effects of these on the performance of the method were less than 6%.
AAS, ICP-MS and direct analysis techniques were compared using statistical analysis. ICP-MS yielded the lowest detection limit (0.6 ng/L). At this exposure level, the performance of the method appears high enough to allow the method to be used for monitoring Be exposure in some industrial environments. However, the method is not sensitive enough, even with ICP-MS, for determining Be levels in non-occupationally exposed individuals.