Measurement of ultra-trace beryllium in occupational hygiene samples by extraction and fluorescence detection

Beryllium is widely used in industry and commercial products for its unique properties; however, occupational exposure to beryllium particles can cause dermal sensitization and a potentially fatal lung ailment, chronic beryllium disease (CBD). Consequently, exposure limits for beryllium particles in air and action levels on surfaces have been established in efforts to minimize exposure risks for workers. In recent research, a molecular fluorescence method for the determination of trace beryllium in workplace samples, i.e., air filters and dust wipes, was evaluated and validated through intra- and inter-laboratory testing. The procedure entails extraction of sampled beryllium in dilute ammonium bifluoride (aqueous), followed by fluorescence measurement of the complex formed between beryllium and hydroxybenzoquinoline sulfonate (HBQS). The estimated method detection limit is <1 ng Be per air filter or wipe sample, with a dynamic range up to greater than 10 μg per sample. Interferences from numerous metals tested (in >400-fold excess concentration compared to that of beryllium) are negligible or minimal. The procedure is effective for the dissolution and quantitative determination of beryllium extracted from refractory beryllium oxide particles, and was successfully modified for measuring beryllium content in large BeO particles and in soil samples. The method performance compares favorably with methods employing sample digestion in acid mixtures that include hydrofluoric acid, followed by inductively coupled plasma-mass spectrometry. ASTM International voluntary consensus standards and US National Institute for Occupational Safety and Health methods based on the methodology have been promulgated.