Voltammetric determination of trace Tl(I) at disposable screen-printed electrodes modified with bismuth precursor compounds

This work reports the trace determination of Tl(I) by anodic stripping voltammetry (ASV) on novel screen-printed electrodes bulk-modified with bismuth precursor compounds (bismuth oxide, bismuth aluminate and bismuth zirconate). A bismuth-film was formed at the electrode surface as the precursor was reduced to metallic bismuth during the electrolytic preconcentration step. The effect of the fabrication parameters (the type of the bismuth precursor compound and the precursor content in the carbon ink), the instrumental variables (stripping waveform, deposition time and deposition potential) and chemical conditions (supporting electrolyte) were studied in detail. The limits of detection for Tl(I) were in the range 0.9–1.1 μg L−1 while the reproducibility on the same sensor (expressed as the % relative standard deviation (n = 8)), was in the range 6.0–7.2% at the 20 μg L−1 level. The sensors were applied to the determination of Tl(I) in a certified lake water sample. The modified electrodes possess analytical characteristics comparable to electroplated bismuth-film electrodes (BiFEs) and offer a wide scope as mercury-free disposable sensors for screening of trace metals.