Rapid Determination of Trace Iodine in Oilfield Brine Based on Oxidation-Atomic Emission Spectrometry
CHAI Xiao-li1, 2, 4, GAO Dan-dan1, 2, LI Hai-jun1, WANG Bo1, YANG Ke-li1,2, DONG Ya-ping1, 2*, LI Wu1, 3
1. Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, China
2. Qinghai Technology Research and Development Center of Comprehensive Utilization of Salt Lakes Resources, Xining 810008, China
3. Qinghai Provincial Key Laboratory of Resources and Chemistry of Salt Lakes, Xining 810008, China
4. University of Chinese Academy of Sciences, Beijing 100049, China
Abstract：The oilfield brine in Nanyi Mountain, located in the west of Qaidam Basin China, is rich in iodine, which is valuable to exploit. The accurate determination of iodine is very difficult because of the high salinity and complicated composition of the oilfield brine. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) has the advantages of fast, wide linear range, low interference. ICP-AES exhibits low sensitivity and high detection limit for direct determination of iodine due to its high ionization energy, resulting in hardly meet the analysis requirements of trace iodine in hypersaline water. A device integrating sampling, chemical reaction and gas-liquid separation was designed so that the iodide ion could be oxidized to iodine and then imported into ICP-AES for determination. The effective injection volume was increased, and the sample matrix’s influence was reduced to reduce the detection limit, and a rapid detection method for trace iodine in oilfield brine with ICP-AES was established. Better conditions of oxidation were 10 mmol·L-1 NaNO2 and 1 mol·L-1 HNO3. The detection limit at I 178.276 nm was 1.65 μg·L-1, and measurement could be completed in three minutes. Partial factor experiments were designed to investigate the interference of main coexisting ions (such as potassium, sodium, calcium, magnesium, lithium, strontium, ammonium). Results indicated that calcium had a significant effect on the determination of iodine at the 95% confidence level. This interference could be eliminated by appropriate dilution. The iodine contents in practical oilfield brine of different evaporative concentration stages were determined with a standard curve, and the recoveries were in the range of 90%～104%. This method was characterized by simple operation, low matrix interference and high accuracy. It will be a promising technique for detecting iodine in oilfield brine samples in the future, which can provide basic data for the extraction technology of iodine.
柴小丽，高丹丹，李海军，王 波，杨克利，董亚萍，李 武. 氧化-原子发射光谱快速测定油田水中微量碘[J]. 光谱学与光谱分析, 2021, 41(05): 1574-1579.
CHAI Xiao-li, GAO Dan-dan, LI Hai-jun, WANG Bo, YANG Ke-li, DONG Ya-ping, LI Wu. Rapid Determination of Trace Iodine in Oilfield Brine Based on Oxidation-Atomic Emission Spectrometry. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2021, 41(05): 1574-1579.
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