Abstract
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.
Highlights
Mercury occurs naturally in the earth’s crust and undergoes complex changes in a number of cycles in the environment caused by natural and human-induced activities
The preferred method of mercury determination has been mercury cold vapour generation (CVG) and several reductants have been investigated for the reduction of Hg(II) to Hg(0), most frequently, sodium/potassium tetrahydroborate (THB)[4,5,6,7] and stannous chloride.[8,9,10,11]
The optimum Ag content is approximately 0.6%. These results demonstrate the incorporation of noble metal onto the TiO2 surface changes the rate of electron transfer during catalyzed cold vapour generation
Summary
Mercury occurs naturally in the earth’s crust and undergoes complex changes in a number of cycles in the environment caused by natural and human-induced activities. Most of the mercury in water, soil, sediments, method development for the cost-effective, fast and sensitive determination of mercury in environmental and biological materials has been vigorous in recent years. The preferred method of mercury determination has been mercury cold vapour generation (CVG) and several reductants have been investigated for the reduction of Hg(II) to Hg(0), most frequently, sodium/potassium tetrahydroborate (THB)[4,5,6,7] and stannous chloride.[8,9,10,11]. Determination of mercury utilizing CVG requires a large amount of concentrated chemical reductants causing contamination of analyzed samples and forming a large amount of gaseous by-products and waste.
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