Institute of Electrical Engineering and Measurement Technology, Department of Sensors and Measurement Technology, Leibniz University Hannover, 30167 Hannover Germany.
Department of Chemistry, Washington State University, Pullman, Washington 99164, United States.
J Am Soc Mass Spectrom. 2023 Jul 5;34(7):1283-1294. doi: 10.1021/jasms.3c00013. Epub 2023 Jun 5.
With ion mobility spectrometry increasingly used in mass spectrometry to enhance separation by increasing orthogonality, low ion throughput is a challenge for the drift-tube ion mobility experiment. The High Kinetic Energy Ion Mobility Spectrometer (HiKE-IMS) is no exception and routinely uses duty cycles of less than 0.1%. Multiplexing techniques such as Fourier transform and Hadamard transform represent two of the most common approaches used in the literature to improve ion throughput for the IMS experiment; these techniques promise increased duty cycles of up to 50% and an increased signal-to-noise ratio (SNR). With no instrument modifications required, we present the implementation of Hadamard Transform on the HiKE-IMS using a low cost, high-speed (600 MHz), open source microcontroller, a Teensy 4.1. Compared to signal average mode, 7- to 10-bit pseudorandom binary sequences resulted in increased analyte signal by over a factor of 3. However, the maximum SNR gain of 10 did not approach the theoretical gain largely due to capacitive coupling of the ion gate modulation with the Faraday plate used as a detector. Even when utilizing an inverse Hadamard technique, capacitive coupling was not completely eliminated. Regardless, the benefits of multiplexing IMS coupled to mass spectrometers are well documented throughout literature, and this first effort serves as a proof of concept for multiplexing HiKE-IMS. Finally, the highly flexible Teensy used in this effort can be used to multiplex other devices or can be used for Fourier transform instead of Hadamard transform.
随着离子淌度谱技术在质谱分析中越来越多地被用于提高正交性，从而增强分离效果，低离子传输率成为了漂移管离子淌度实验的一大挑战。高动能离子淌度谱仪（HiKE-IMS）也不例外，其通常使用的占空比小于 0.1%。傅里叶变换和 Hadamard 变换等多路复用技术是文献中常用于提高 IMS 实验离子传输率的两种最常见方法；这些技术有望将占空比提高到 50%，并提高信号与噪声比（SNR）。我们无需对仪器进行任何修改，就在 HiKE-IMS 上实现了 Hadamard 变换，使用的是低成本、高速（600MHz）、开源微控制器 Teensy 4.1。与信号平均模式相比，7 位到 10 位伪随机二进制序列使分析物信号增加了 3 倍以上。然而，最大 10 倍的 SNR 增益并没有接近理论上的增益，这主要是由于离子门调制与用作检测器的法拉第盘之间的电容耦合。即使采用逆 Hadamard 技术，也不能完全消除电容耦合。尽管如此，文献中已经充分证明了将多路复用 IMS 与质谱仪相结合的好处，而这首次尝试则为多路复用 HiKE-IMS 提供了一个概念验证。最后，在这项工作中使用的高度灵活的 Teensy 不仅可以用于多路复用其他设备，还可以用于傅里叶变换而不是 Hadamard 变换。
