铊(Thallium, Tl)是一种有毒的金属元素, 主要用于半导体、 电子设备、 农药和灭鼠剂的生产, 会对职业人群的身体健康造成潜在的威胁, 工作场所空气中铊及其化合物浓度的测定对保证职业人群的健康具有重要意义。 虽然工作场所空气中痕量铊的毒性高于其他有毒金属元素, 但对其研究却很少。 目前工作场所空气中铊及其化合物浓度检测方法主要是原子吸收光谱法(AAS), 但该方法有不足之处。 建立了超声浸提-No Gas-电感耦合等离子体质谱(ICP-MS)测定工作场所空气中铊及其化合物(以²⁰⁵Tl计)的新方法。 在采样点, 按照GBZ 159—2004方法用0.8 μm孔径的微孔滤膜对工作场所空气进行短时间采样。 检测过程中, 考察了不同超声浸提条件对测定结果的影响, 并对质谱干扰及消除进行了分析。 最终优化的实验条件为3%硝酸在室温条件下对采集的滤膜样品进行超声浸提10 min, 采用No Gas模式对工作场所空气中铊及其化合物(以²⁰⁵Tl计)进行ICP-MS分析。 在该实验条件下得出铊及其化合物在0.087~80 ng·mL^-1浓度范围内呈现良好的线性关系( Y=0.009 2 X-0.001 8, R=0.999 9); 检出限为0.026 ng·mL^-1, 当采样体积为75 L时, 最低检出浓度为0.001 7 μg·m^-3, 最低定量浓度为0.005 7 μg·m^-3。 用质控样品(滤膜中铊质量控制样品ZK147和ZK148)验证了本方法的精密度和准确度, 结果显示测定值与参考值之间无显著性差异, 相对标准偏差(RSD)为0.77%和0.86%。 用加标法(3倍于滤膜中铊含量的常见干扰元素)对建立的新方法进行干扰分析, 回收率在97.2%~106.7%之间, 表明本法抗干扰能力较强。 用本法与国标方法《工作场所空气有毒物质测定 第25部分: 铊及其化合物》(GBZ/T 300.25—2017)溶剂洗脱-石墨炉原子吸收光谱法相比较, 10个实际样品的测定结果基本一致。 相对于现行国标方法, 该方法具有操作简单、 检出限低、 线性范围宽和准确度高的优点, 能够满足实际工作场所空气中铊及其化合物的准确、 快速、 痕量及高通量测定需求。 该方法有望成为工作场所空气中铊及其化合物测定的新方法, 可更高效地为特定职业人群健康监护提供参考和依据。

Thallium (Tl), an extremely toxic metal element, was mainly used to manufacture semiconductors, electronic equipment, pesticide, and rodenticide. The determination of thallium and its compounds in workplace air was of great significance to ensure the health of the occupational people because they posed a potential threat to their physical health. Although trace amounts of thallium were more toxic than other toxic metals in the workplace air, little research was done. At present, atomic absorption spectrometry (AAS) was the main method for thallium assay in workplace air, but this method had some shortcomings. Therefore, we proposed a new method for the determination of thallium and its compounds in workplace air by ultrasonic extraction-inductively coupled plasma mass spectrometry (ICP-MS) using No Gas mode. At the sampling point, the short sampling workplace air was sampled by a microporous membrane with an aperture of 0.8 μm according to GBZ 159—2004 method. The effect of ultrasonic extraction conditions on the result was investigated, and the interference and elimination of mass spectrometry were analyzed. The optimized experimental conditions were 3% HNO₃ for ultrasonic extraction of the filter membrane samples for 10 min at room temperature and No Gas mode for ICP-MS analysis. Under the optimal conditions, good linearity was obtained in the range of 0.087 to 80 ng·mL^-1, with linear calibration curves of Y=0.009 2 X-0.001 8 ( R=0.999 9). The detection limit (LOD) was 0.026 ng·mL^-1. When the sampling volume was 75 L, the minimum detected concentration was 0.001 7 g·m^-3, and the minimum quantitative concentration was 0.005 7 g·m^-3. The precision and accuracy of the method were verified by the quality control samples (thallium quality control samples ZK147 and ZK148 in the filter membrane). The results showed no significant difference between the measured value and the reference value, and the relative standard deviation (RSDs) was 0.77% and 0.86%. Interference analysis of the new method was carried out by adding standard method (common interfering elements with 3 times the thallium content in membranes), and the recovery rate was between 97.2% and 106.7%, indicating that the method had strong anti-interference ability. Comparing with the national standard method of “Determination of toxic substances in workplace air-Part 25: Thallium and its compounds” GBZ/T 300.25—2017 solvent elution-graphite furnace atomic absorption spectrometry (GFAAS), the results of 10 samples were basically consistent. And the proposed method exhibited a simpler operation, lower detection limit, wider linear range and higher accuracy, which met the needs of accurate, rapid, trace and high-throughput determination of thallium and its compounds in samples. The new method is expected to be a new method for the determination of thallium and its compounds in workplace air and can provide reference and basis for health monitoring of specific occupational groups more effectively.