微波等离子体炬分子同位素光谱法用于溶液中硼同位素定量分析

Quantitative Analysis of Boron Isotopes in Solution by Microwave Plasma Torch Molecular Isotopic Spectroscopy

摘要

针对溶液体系中硼同位素比例的快速分析需求, 建立了一种微波等离子体炬分子同位素光谱法(Microwave plasma torch molecular isotopic spectrometry, MPT-MIS), 用于溶液中硼同位素比例的定量分析. 该方法利用微波等离子体炬(MPT)激发BO₂分子发射光谱, 并结合偏最小二乘回归(PLSR)从全谱形状信息中提取硼同位素丰度信息, 实现了硼同位素比例的快速测定. 通过使用石英内管有效降低了硼的记忆效应, 并基于“留一法”交互验证(Leave-one-out cross validation, LOOCV)系统优化了光谱预处理方式和波长区间. 在最优预处理组合(一阶导数+面积归一化+25点平滑)和最优波长区间(464~589 nm)下, 仅需2个潜变量(Latent variables, LVs)即可充分提取与同位素丰度相关的光谱信息. 在验证集的3 个样品上模型预测¹¹B/¹⁰B 的相对偏差(Relative bias)最大为2.04%, 预测精密度为1%~2%(2σ). 此外, 实验还发现BO₂分子光谱强度与总硼浓度在5~3000 μg/mL范围内呈现良好的线性关系(R²>0.999), 表明该方法具备同步测定总硼浓度的潜力, 为核工业等场景中硼同位素比和总硼浓度的在线同步分析提供了一种操作简便、 成本较低的新方案.

Abstract

To meet the demand for rapid analysis of boron isotope ratios in solution systems， this study established a microwave plasma torch molecular isotopic spectrometry（MPT-MIS） method for the quantitative determination of boron isotope ratios in solutions. The method employs a microwave plasma torch（MPT） to excite the emission spectrum of BO₂ molecules and combines partial least squares regression（PLSR） to extract boron isotopic abundance from full-spectral shape， enabling rapid measurement of boron isotope ratios. The memory effect of boron was effectively reduced by using a quartz inner tube， and the spectral preprocessing methods as well as the wavelength range were systematically optimized based on leave-one-out cross-validation（LOOCV）. Under the optimal preprocessing combination（first derivative+area normalization+25-point smoothing） and the optimal wavelength range（464—589 nm）， only two latent variables（LVs） were needed to sufficiently extract the spectral information related to isotope abundance. On the three samples in the validation set， the maximum relative bias of the model-predicted¹¹B/¹⁰B ratio was 2.04%， and the prediction precision was 1%—2%（2σ）. Furthermore， it was found experimentally that the BO₂ molecular spectral intensity exhibited a good linear relationship with total boron concentration in the range of 5—3000 μg/mL（R²>0.999）， indicating the potential of this method for simultaneous determination of total boron concentration. This provides a simple and low-cost new approach for the online simultaneous analysis of boron isotope ratios and total boron concentration in scenarios such as the nuclear industry.

关键词

硼同位素 / BO₂分子光谱 / 微波等离子体炬 / 偏最小二乘回归

Key words

Boron isotope / BO₂ molecular spectroscopy / Microwave plasma torch / Partial least squares regression

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基金资助

湖州市科技计划项目(2025GY018)