Determination of ultratrace bismuth in milk samples by atomic fluorescence spectrometry

A sensitive procedure was developed for determination of bismuth (Bi) in milk samples by hydride generation atomic fluorescence spectrometry (HG-AFS) after microwave-assisted sample digestion with HNO3 and H2O2. The method provides a sensitivity of 1832 fluorescence units (ng/mL) with a detection limit of 0.01 ng/mL, which corresponds to 20 pg absolute limit of detection, equivalent to 0.50 ng/g in the original sample. Application of the methodology to cow milk samples from the Spanish market showed the presence of Bi at a concentration of 11.8-28.8 ng/g, which compared well with data obtained after dry ashing of samples and with data obtained by inductively coupled plasma-mass spectrometry after microwave-assisted digestion.