Validation of a standardized method for determining beryllium in human urine at ng level

Beryllium may be toxic at low levels of exposure and need therefore a biological and/or air monitoring strategy in order to monitor subject’s exposure. The main objective of the work presented in this manuscript was to develop and validate a sensitive and reproducible method for determining levels of beryllium in human urine and to establish reference values in workers and in non-occupationally exposed people.
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, residual was solubilized in nitric acid and analyzed by Atomic Absorption Spectrometry and/or Inductively Coupled Plasma Mass Spectrometry.
The proposed method is 4 to 100 times more sensitive than other methods currently in routine use. This new method was validated with the Concordance Correlation Coefficient test for beryllium concentrations ranging from 10 to 100 ng/L. The creatinine concentration, urine pH, interfering compounds and freeze-thaw cycles have a slight effect on the performance of the method (less than 6%).
The effectiveness of the two analytical techniques were compared statistically with each other and to direct analysis techniques. Even with a detection limit of 0.6 ng/L (obtain with ICP-MS), the method is not sensitive enough to detect levels in non-occupationally exposed persons. The method performance does however appear to be suitable for monitoring worker exposure in some industrial settings and it could therefore be of use in biological monitoring strategies.