Nano-Ag particles loaded on TiO2 (Ag-TiO2) were used as catalyst for the UV-induced cold vapour generation with formic acid coupled to atomic absorption for determination of total mercury in analytical samples. The reducing activity of Ag-TiO2 was compared with two semiconductor catalysts: unmodified TiO2 and ZnO. The effect of catalyst type, its concentration in the analyzed sample, sample pH, formic acid concentration and ultraviolet irradiation time have been investigated. In the presence of formic acid, most effective in the reduction of mercury was Ag-TiO2. Under the optimized experimental conditions recovery of mercury in four reference materials containing 0.20-1.99 µg g-1 Hg was 95-99% of certificate values. The relative standard deviation for samples was equal to or better than 11%. Certified reference materials (corresponding to biological and environmental samples) analysis using the Ag-TiO2-UV-CVGAAS method revealed that it is promising for mercury determination in analytical samples at ultratrace level.
photocatalytic reduction; UV-induced cold vapour generation; mercury determination; nano-Ag-TiO2
