Determination of Trace Bismuth in Environmental Waters by ICP-MS with Cobalt Ion-Assisted Photochemical Vapour Generation

With increasing use of bismuth in industry, a better understanding of its environmental behaviour is required, including an improved knowledge of its background concentration range in (non-saline) freshwaters. However, the poor analytical sensitivity of previous methods may lead to inaccurate measurement results for Bi 3+ in environmental samples. In this work, cobalt ion-assisted photochemical vapour generation (PVG) was developed for the detection of trace Bi with inductively coupled plasma-mass spectrometry (ICP-MS) measurement. The volatile species of Bi was found to be (CH 3 ) 3 Bi generated under UV irradiation in the presence of formic acid, acetic acid and Co 2+ . The major parameters potentially influencing the detection of Bi were investigated. Under optimised conditions, the limit of detection (3 s , n = 11) of the proposed method was 0.3 ng l −1 . The analytical sensitivity was enhanced about 70-fold for Bi 3+ compared with that using classic pneumatic nebulisation of ICP-MS. Furthermore, the proposed method showed better analytical sensitivity and anti-interference ability towards co-existing ions compared with ferric ion-assisted PVG systems. The accuracy of the proposed method was evaluated by analysis of environmental water samples and certified reference materials with satisfactory results.