密闭酸溶-高分辨电感耦合等离子体质谱法测定高纯石英砂中的杂质元素

Determination of Impurity Elements in High-Purity Quartz by High-Resolution Inductively Coupled Plasma-Mass Spectrometry with Closed-Vessel Acid Digestion

  • 摘要: 高纯石英砂(SiO2含量≥99.998%)是半导体和光伏产业的核心基础材料,杂质元素的含量直接影响产品的性能,其总含量需严格控制在20μg/g以内。高纯石英砂中杂质元素测定方法主要使用电感耦合等离子体质谱法(ICP-MS)和发射光谱法(ICP-OES)。ICP-MS具有极低检出限和高灵敏度,但受限于分辨率,单四极杆ICP-MS在测定时部分元素多原子离子质谱干扰严重。样品分解方法主要采用氢氟酸单一酸溶或混合酸溶。酸溶过程中试剂用量大,难溶元素溶解不完全,挥发性元素易损失。本文采用氢氟酸和硝酸密闭酸溶分解样品,甘露醇溶液络合硼元素,利用高分辨电感耦合等离子体质谱法(HR-ICP-MS)对高纯石英砂中16种杂质元素进行测定。密闭酸溶强毒性试剂用量少,样品分解完全,甘露醇络合避免了挥发性元素损失,合适的同位素和中高分辨率模式(R≥4000)可区分待测元素和干扰离子的质谱峰,解决了多原子离子干扰问题。应用本方法对国际IOTA-CG高纯石英砂标准品和实际样品进行测定,标准品测定结果与标准值相符,各元素的相对误差(RE)≤10.0%,实际样品的加标回收率为92.0%~108.0%,相对标准偏差(RSD,n=12)≤9.78%,检出限为0.000089~0.33μg/g。该方法解决了高纯石英砂中多元素同时准确测定的难题,为高纯石英砂的品质评估及高端应用提供了技术支撑。

     

    Abstract: High-purity quartz sand (with an SiO2 content ≥99.998%) is a critical raw material in the semiconductor and photovoltaic industries. The content of impurity elements directly influences product performance, and their total concentration must be strictly controlled below 20μg/g. Inductively coupled plasma-mass spectrometry (ICP-MS) and inductively coupled plasma-optical emission spectroscopy (ICP-OES) are the primary techniques used for the determination of impurity elements in high-purity quartz sand. ICP-MS offers extremely low detection limits and high sensitivity. However, single-quadrupole ICP-MS suffers from significant mass spectral interferences caused by polyatomic ions, particularly due to its limited mass resolution. Common sample decomposition methods include single-acid digestion with hydrofluoric acid (HF) or mixed-acid digestion. Nevertheless, these approaches often require large amounts of reagents, may result in incomplete dissolution of refractory elements, and can lead to the loss of volatile components. In this study, high-purity quartz sand samples were decomposed using a closed-vessel acid digestion method with hydrofluoric and nitric acids. Boron was complexed with a mannitol solution to minimize its loss. A total of 16 impurity elements were accurately determined by high-resolution inductively coupled plasma-mass spectrometry (HR-ICP-MS). The closed-vessel acid digestion method employed a minimal amount of highly toxic reagents, achieved complete sample decomposition, and utilized mannitol complexation to prevent the loss of volatile elements. Appropriate isotope selection and medium-to-high resolution settings (R ≥ 4000) effectively separated the mass spectral peaks of target elements from those of interfering ions, thereby mitigating polyatomic ion interferences. This method was applied to the analysis of a high-purity quartz sand international standard reference material (IOTA-CG) and several real samples. The results obtained for the standard sample were in good agreement with the certified values, with relative error (RE) for all elements ≤10.0%. For the real samples, the standard addition recovery rates ranged from 92.0% to 108.0%, the relative standard deviation (RSD, n=12) for all elements were ≤9.78%, and the limits of detection (LOD) ranged from 0.000089μg/g to 0.33μg/g. This method addresses the challenge of accurately and simultaneously determining multiple elements in high-purity quartz sand, providing technical support for its quality evaluation and high-end applications.

     

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