Department of Chemistry, Clemson University, Clemson, South Carolina 29634, United States.
Spectroswiss, 1015 Lausanne, Switzerland.
J Am Soc Mass Spectrom. 2021 May 5;32(5):1224-1236. doi: 10.1021/jasms.1c00051. Epub 2021 Apr 1.
Isotope ratio (IR) analysis of natural abundance uranium presents a formidable challenge for mass spectrometry (MS): the required spectral dynamic range needs to enable the quantitatively accurate measurement of the UO species present at ∼0.0053% isotopic abundance. We address this by empowering a benchtop Orbitrap Fourier transform mass spectrometer (FTMS) coupled with the liquid sampling-atmospheric pressure glow discharge (LS-APGD) ion source and an external high-performance data acquisition system, FTMS Booster X2. The LS-APGD microplasma has demonstrated impressive capabilities regarding elemental and IR analysis when coupled with Orbitrap FTMS. Despite successes, there are limitations regarding the dynamic range and mass resolution that stem from space charge effects and data acquisition and processing restrictions. To overcome these limitations, the FTMS Booster was externally interfaced to an LS-APGD Q Exactive Focus Orbitrap FTMS to obtain time-domain signals (transients) and to process unreduced data. The unreduced time-domain data acquisition with user-controlled processing permit the evaluation of the effects of in-hardware transient phasing, increased transient lengths, advanced transient coadding, varying the length of a transient to be processed with a user-defined time increment, and the use of absorption-mode FT (aFT) processing methods on IR analysis. The added capabilities extend the spectral dynamic range of the instrument to at least 4-5 orders of magnitude and provide a resolution improvement from ∼70k to 900k /Δ at 200 /. The empowered LS-APGD Orbitrap platform allows for the simultaneous measurement of UO and the prominent UO and UO isotopic species at their natural abundances, ultimately yielding improvements in performance when compared to previous uranium IR results on this same Q Exactive Focus instrument.
天然丰度铀的同位素比（IR）分析对质谱（MS）提出了巨大的挑战：所需的光谱动态范围需要能够对 UO 物种进行定量准确的测量，其丰度约为 0.0053%。我们通过为台式 Orbitrap 傅里叶变换质谱仪（FTMS）配备液体采样常压辉光放电（LS-APGD）离子源和外部高性能数据采集系统 FTMS Booster X2 来解决此问题。当与 Orbitrap FTMS 结合使用时，LS-APGD 微等离子体在元素和 IR 分析方面表现出令人印象深刻的能力。尽管取得了成功，但由于空间电荷效应以及数据采集和处理的限制，存在动态范围和质量分辨率方面的限制。为了克服这些限制，FTMS Booster 被外部连接到 LS-APGD Q Exactive Focus Orbitrap FTMS 上，以获取时域信号（瞬变）并处理未还原的数据。用户控制处理的未还原时域数据采集允许评估硬件瞬变相位、增加瞬变长度、先进的瞬变叠加、以用户定义的时间增量处理的瞬变长度变化以及在 IR 分析中使用吸收模式傅里叶变换（aFT）处理方法的影响。附加功能将仪器的光谱动态范围扩展到至少 4-5 个数量级，并提供从 ∼70k 到 900k /Δ的分辨率提高，在 200 / 时。功能强大的 LS-APGD Orbitrap 平台允许同时测量 UO 和 UO 和 UO 同位素物种在其天然丰度下的含量，与同一 Q Exactive Focus 仪器上以前的铀 IR 结果相比，最终提高了性能。
