高温热水解离子色谱法快速同时测定粘土中的卤素

建立高温热水解分解粘土样品,离子色谱快速同时测定其中的氟、氯、溴和碘含量的方法。优化了影响粘土高温热水解的主要参数,得到以下最佳测定条件:2.0 g粘土,反应温度1000℃,停留时间10 min,样品与催化剂V2O5质量比为1∶1,空气流量90 mL/min,15 mL 5.4 mmol/L Na2CO3和5.1 mmol/L NaHCO3混合溶液为粘土释放卤素的吸收液;考察了粘土高温热水解后卤素的赋存形态。结果表明,这些卤素在吸收液中以F!、Cl!、Br!和I!形式存在,且能被离子色谱很好地分离。粘土样品较好的卤素加标回收率和较小的相对标准偏差及土壤标准物质中卤素的评估说明本方法的准确度和精密度良好。分析了4个粘土样品,氟、氯、溴和碘的检出限分别为0.030,0.043,0.09和0.13#g/g,本方法简单、可靠、低消耗和快速,每小时可分析5个样品,可同时分析粘土和其它无机基质中的氟、氯、溴和碘的含量。

Simultaneous Rapid Determination of Halogens in Clay Using Pyrohydrolysis Combined with Ion Chromatography

An ion chromatography (IC) method for rapid determination of halogens (F, Cl, Br and I) simultaneously in clay with pyrohydrolysis as sample digestion was developed. The parameters that significantly affect pyrohydrolysis were investigated and the following conditions of pyrohydrolysis were optimized. 2.0 g clay sample and V₂O₅ were put into the reactor at 1000 °C for 10 min; the mass ratio of clay sample to accelerator V₂O₅ was 1:1 and air flow rate was 90 mL min^-1; 15 mL solution containing 5.4 mM Na₂CO₃ and 5.1 mM NaHCO₃ was used as receiver solution. The detection of analyte by this method following the proposed pyrohydrolysis procedure indicated that F, Cl, Br and I in clay were presented as F⁻, Cl⁻, Br⁻ and I⁻ in receiver solution which were well separated by IC. The accuracy of this approach was confirmed by the analysis of four clays spiked with Chinese Soil Reference Materials (SRMs). The limits of detection (LOD) were 0.030, 0.043, 0.09 and 0.13 μg g⁻¹ for F, Cl, Br and I, respectively. By using a relatively simple and low cost pyrohydrolysis system, up to five samples can be processed per hour, and then F, Cl, Br and I can be determined in clay and other inorganic samples.