改装元素分析—稳定同位素比值质谱联用仪测定固体样品硫同位素

本文对元素分析—稳定同位素比值质谱联用仪（EA-IRMS）进行改装，并利用其测定不同形态硫同位素标准物质和样品。结果表明，在色谱柱后加装SO₂气体捕集管，可捕集氧化还原产生的SO₂气体，并重复调用作为参考气使用，无需外部引入高纯SO₂气体，减小了其对仪器管路腐蚀和实验室环境危害；硫酸钡进样量约400 μg时，捕集管中的SO₂气体可提供至少20次峰中心聚焦；改装后的EA-IRMS系统测试硫同位素标准物质（IAEA-SO-5、 IAEA-S-2、IAEA-S-3、EMA-P1），当硫元素进样量为20 μg时，δ³⁴S值测试精度达到0.2‰（n=3），4种国际标准物质测量值与真实值相关系数良好（R²=1），表明硫的不同化合物δ³⁴S值可以相互校准，也表明EA-IRMS改装后可以满足硫同位素测试精度的要求。

Modification of Elemental Analysis-Stable Isotope Ratio Mass Spectrometer Combined Instrument for Determination of Sulfur Isotopes in Solid Samples

In this paper, the elemental analysis-stable isotope ratio mass spectrometer (EA-IRMS) is modified to testing different forms of sulfur isotope standard material and sample. A SO₂ gas trap tube is installed after chromatographic column to trap the SO₂ gas generated by redox reaction and the captured SO₂ can be used as reference gas several times, there is no need to introduce high-purity SO₂ gas externally, which reduces the damage to the instrument pipeline corrosion and laboratory environment. When the amount of barium sulfate is about 400 μg, SO₂ gas in the trap tube can provide at least 20 peak center focus. Modified EA-IRMS system testing sulfur isotope standard material (IAEA-SO-5, IAEA-S-2, IAEA-S-3, EMA-P1), when the sulfur element injection volume is 20 μg, the δ³⁴S value test accuracy achieve 0.2‰(n=3), 4 kinds of international standard material measured value and true value have a good correlation coefficient (R²=1), it indicates that the δ34S value of different compounds of sulfur can be mutual calibration, and the modified EA-IRMS can meet the accuracy requirement of the sulfur isotope test.