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王娜, 滕新华, 吴彦涛, 曾江萍, 吴良英, 陈枫. 三氯化铝浸取-火焰原子吸收光谱法测定水系沉积物中低含量的碳酸铁[J]. 岩矿测试, 2015, 34(2): 229-233. DOI: 10.15898/j.cnki.11-2131/td.2015.02.013
引用本文: 王娜, 滕新华, 吴彦涛, 曾江萍, 吴良英, 陈枫. 三氯化铝浸取-火焰原子吸收光谱法测定水系沉积物中低含量的碳酸铁[J]. 岩矿测试, 2015, 34(2): 229-233. DOI: 10.15898/j.cnki.11-2131/td.2015.02.013
Na WANG, Xin-hua TENG, Yan-tao WU, Jiang-ping ZENG, Liang-ying WU, Feng CHEN. Determination of Low-content Iron Carbonate in Stream Sediments by Flame Atomic Absorption Spectrometry with Aluminum Chloride Extraction[J]. Rock and Mineral Analysis, 2015, 34(2): 229-233. DOI: 10.15898/j.cnki.11-2131/td.2015.02.013
Citation: Na WANG, Xin-hua TENG, Yan-tao WU, Jiang-ping ZENG, Liang-ying WU, Feng CHEN. Determination of Low-content Iron Carbonate in Stream Sediments by Flame Atomic Absorption Spectrometry with Aluminum Chloride Extraction[J]. Rock and Mineral Analysis, 2015, 34(2): 229-233. DOI: 10.15898/j.cnki.11-2131/td.2015.02.013

三氯化铝浸取-火焰原子吸收光谱法测定水系沉积物中低含量的碳酸铁

Determination of Low-content Iron Carbonate in Stream Sediments by Flame Atomic Absorption Spectrometry with Aluminum Chloride Extraction

  • 摘要: 传统的氯化铵浸取-重铬酸钾滴定法(邻二氮菲比色法)可有效分析试样中较高含量的碳酸铁(7.5%~80%), 但试剂消耗量大、测定步骤冗长、分析误差相对较大, 水系沉积物中碳酸铁含量较低, 采用此方法分析时其他含铁矿物的干扰易引入测量误差。本研究采用三氯化铝水浴加热浸取, 建立了火焰原子吸收光谱法(FAAS)测定水系沉积物中低含量碳酸铁(0.1%~6.0%)的分析方法。使用80 mL浓度为100 g/L的三氯化铝溶液水浴加热60 min, 可完全浸取试样中的碳酸铁; 在标准曲线中加入与待测样品浓度相同的三氯化铝, 有效地避免了浸取剂三氯化铝的基体干扰。碳酸铁的检出限为0.015 μg/mL, 精密度为2.3%~4.0%(n=12), 加标回收率为95.0%~107.5%。沉积物中常见的含铁矿物(如赤铁矿和磁铁矿)对碳酸铁的测定干扰可忽略, 磁黄铁矿的干扰可通过加入氯化汞消除。本法比传统化学分析方法的操作简便, 准确度和精密度高, 解决了其他含铁矿物的干扰问题。

     

    Abstract: Potassium dichromate titration (othophenanthroline spectrophotometry) with ammonium chloride extraction is a reliable technique to determine the high-content iron carbonate (7.5%-80%) in samples. However, the traditional methods have the disadvantages of complicated operation, large reagent consumption and analytical error. Moreover, due to the low-content iron carbonate in stream sediments, the interferences caused by other ferrous minerals easily leads to the increase of measurement error. A highly sensitive and selective method for determination of low-level iron carbonate (0.1%-6.0%) in stream sediments has been developed by Flame Atomic Absorption Spectrometry (FAAS) combined with aluminum chloride extraction in water bath and is reported in this paper. Extraction conditions were optimized so that iron carbonate in stream sediments could be completely extracted when the concentration of aluminum chloride is 100 g/L, the heating time is 60 min for water bath, and extract dosage is 80 mL. The addition of aluminum chloride with the same concentration in the standard curve can eliminate matrix interference. The detection limit of iron carbonate was 0.0015 μg/mL, the relative standard deviation (n=12) was 2.3%-4.0% and the recovery ranges from 95.0% to 107.5%. Some ferrous minerals in stream sediments such as hematite and magnetite have negligible interference on the determination of iron carbonate and the interference from pyrrhotine could be also effectively eliminated by mercuric chloride. Compared with the chemical method, the proposed method is simple and easy to operate and has high accuracy and precision.

     

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