Abstract
This work reports the development of a novel extraction method for total Hg determination in oil samples. After extracting Hg from samples it was quantified in the extracts by cold vapor atomic absorption spectrometry (CV-AAS), employing a laboratory-made gas–liquid separator (GLS) and NaBH4 as reducing agent. The extraction of Hg from samples was carried out by extraction induced by emulsion breaking (EIEB), which is based on the formation and breaking of water-in-oil emulsion between the oil samples and an extractant solution containing an emulsifying agent (surfactant) and nitric acid. Operational parameters of the GLS were evaluated in order to set the best performance of the measurement system. In these studies it was proven that the volume of sample and the concentration of HCl added to the sample extracts had significant influence on Hg response. The best conditions were achieved by adding 0.5mL of a 0.3molL−1 HCl solution on 1mL of sample extract. The extraction conditions were also optimized. The highest efficiency was observed when 4mL of a solution containing 2.5% triton X-100 and 15% v/v HNO3 were employed for the extraction of Hg contained in 20mL of sample. Emulsion breaking was performed by heating at 80°C and took approximately 20min. The limit of quantification of the method was 1.9µgL−1 and recovery percentages between 80% and 103% were observed when spiked samples (2 and 10µgL−1) of diesel oil, biodiesel and mineral oil were analyzed.
Published Version
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