Determination of Mercury and Arsenic in Oil-bearing Core by Soxhelt Extraction-Atomic Fluorescence Spectrometry

• Published in: Yankuàng cèshì Vol. 38; no. 4; pp. 461 - 467
• Main Authors: Qiao, Ning-qiang, Xue, Zhi-wei, Wang, Gang-feng, Luo, Dan
• Format: Journal Article
• Language: Chinese; English
• Published: Beijing National Research Center of Geoanalysis 01.07.2019; Science Press, PR China
• Subjects: aqua regia; Arsenic; atomic fluorescence spectrometry; Bearing; Crude oil; Decomposition; Decomposition reactions; Fluorescence; High temperature; Hydrophobicity; Mercury (metal); Methods; oil-bearing core; Operating temperature; Organic matter; Oxidation; Scientific imaging; soxhelt extraction; Spectrometry; Spectroscopy; Standard deviation
• ISSN: 0254-5357
• DOI: 10.15898/j.cnki.11-2131/td.201812030128

BACKGROUND: Crude oil had a great influence on the determination of mercury and arsenic in oil-bearing cores by atomic fluorescence spectrometry. At present,the main methods of removing organic matter such as crude oil are high-temperature firing and high-temperature oxidation with strong acid. In these methods,high reaction temperature will cause loss of mercury and arsenic,resulting in lower results.OBJECTIVES: To develop a separation method with low operating temperature.METHODS: Mercury and arsenic in oil-bearing cores were determined by atomic fluorescence spectrometry with Soxhlet extraction at a low temperature for this method of 75℃ and the remaining part was decomposed by 50%aqua regia.RESULTS: The detection limits were 0. 003 mg/kg and 0. 10 mg/kg for mercury and arsenic,respectively. The relative standard deviations were 7. 3% and 5. 1%,respectively. The relative standard deviation of mercury decreased from 33. 0% to 7. 3%,and the relative standard deviation of arsenic decreased from 25. 0% to 5. 1%.The recoveries of standard addition were greater than 92. 5%.CONCLUSIONS: Compared with traditional methods,this method avoided the problems of insufficient contact between samples and aqua regia due to the hydrophobicity of crude oil,incomplete decomposition of samples and mercury loss due to excessive reaction temperature. The proposed method provides a reference for the determination of other elements in oil-bearing cores.