气相色谱–质谱联用法测定水体中苯胺的不确定度

Uncertainty Evaluation for the Determination of Aniline in Water by Gas Chromatography-Mass Spectrometry

摘要: 苯胺作为典型的含共轭大π键芳香胺污染物，具有强致癌性与水环境持久性，水体中苯胺的精准定量是环境分析化学与生态风险评价的重要基础。本文以内标校正气相色谱–质谱联用(GC-MS)技术测定水体苯胺，依据定量全流程建立误差传递数学模型，系统拆分并量化样品平行测定、液液萃取前处理、标准溶液逐级稀释、校准曲线拟合、仪器计量性能，采用方均根法完成不确定度的计算。基质加标水样苯胺平均质量浓度为3.20 μg/L，置信水平95% (k = 2)下扩展不确定度U = 0.478 μg/L。误差溯源结果表明，标准溶液多步稀释累积偏差与最小二乘曲线拟合离散性是决定测量结果不确定度的核心来源。本工作完整地构建了GC-MS测定水中苯胺的标准化不确定度评定体系，阐明有机痕量色谱质谱分析的误差传递规律，为优化标准配制、仪器校准与前处理质控方案、提升水环境有机污染物定量数据的溯源性与可比性提供理论支撑与量化依据。

Abstract: As a typical aromatic amine pollutant with conjugated large π-bonds, aniline is highly carcinogenic and persistent in aquatic environments. Accurate quantification of aniline in water is fundamental to environmental analytical chemistry and ecological risk assessment. In this study, gas chromatography-mass spectrometry (GC-MS) with internal-standard correction was applied to determine aniline in water samples. A mathematical model for error propagation was established covering the whole quantitative procedure. Uncertainty components originating from parallel sample measurements, liquid-liquid extraction pretreatment, serial dilution of standard solutions, calibration-curve fitting and instrumental metrological performance were systematically decomposed and quantified. The combined standard uncertainty was calculated by the root-sum-square method. The average mass concentration of aniline in matrix-spiked water sample was 3.20 μg/L, and the expanded uncertainty was U = 0.478 μg/L at 95% confidence level (k = 2). Error-tracing results demonstrate that cumulative deviation caused by multi-step dilution of standard solutions and dispersion of least-squares calibration-curve fitting constitute the dominant sources of measurement uncertainty. This work constructs a standardized uncertainty-evaluation system for aniline determination in water using GC-MS, and illustrates the error-propagation rule for trace-organic chromatographic-mass spectrometric analysis. It provides theoretical support and quantitative reference for optimizing standard-solution preparation, instrument calibration and pretreatment quality-control strategies, as well as improving traceability and comparability of quantitative data for aquatic organic pollutants.