Department of Chemistry, Wayne State University, Detroit, MI, USA.
MSTM, LLC, Newark, DE, USA.
Rapid Commun Mass Spectrom. 2021 Jan;35 Suppl 1:e8449. doi: 10.1002/rcm.8449. Epub 2019 Jun 4.
Successful coupling of a multi-ionization automated platform with commercially available mass spectrometers provides improved coverage of compounds in complex mixtures through implementation of new and traditional ionization methods. The versatility of the automated platform is demonstrated through coupling with mass spectrometers from two different vendors. Standards and complex biological samples were acquired using electrospray ionization (ESI), solvent-assisted ionization (SAI) and matrix-assisted ionization (MAI).
The MS™ prototype automated platform samples from 96- or 384-well plates as well as surfaces. The platform interfaces with Thermo Fisher Scientific mass spectrometers by replacement of the IonMax source, and on Waters mass spectrometers with additional minor source inlet modifications. The sample is transferred to the ionization region using a fused-silica or metal capillary which is cleaned between acquisitions using solvents. For ESI and SAI, typically 1 μL of sample solution is drawn into the capillary tube and for ESI slowly dispensed near the inlet of the mass spectrometer with voltage placed on the delivering syringe barrel to which the tubing is attached, while for SAI the sample delivery tubing inserts into the inlet without the need for high voltage. For MAI, typically, 0.2 μL of matrix solution is drawn into the syringe before drawing 0.1 μL of the sample solution and dispensing to dry before insertion into the inlet.
A comparison study of a mixture of angiotensin I, verapamil, crystal violet, and atrazine representative of peptides, drugs, dyes, and herbicides using SAI, MAI, and ESI shows large differences in ionization efficiency of the various components. Solutions of a mixture of erythromycin and azithromycin in wells of a 384-microtiter well plate were mass analyzed at the rate of ca 1 min per sample using MAI and ESI. In addition, we report the analysis of bacterial extracts using automated MAI and ESI methods. Finally, the ability to perform surface analysis with the automated platform is also demonstrated by directly analyzing dyes separated on a thin-layer chromatography (TLC) plate and compounds extracted from the surface of a beef liver tissue section.
The prototype multi-ionization automated platform offers solid matrix introduction used with MAI, as well as solution introduction using either ESI or SAI. The combination of ionization methods extends the types of compounds which are efficiently ionized and is especially valuable with complex mixtures as demonstrated for bacterial extracts. While coupling of the automated multi-ionization platform to Thermo and Waters mass spectrometers is demonstrated, it should be possible to interface it with most commercial mass spectrometers.
成功地将多离子化自动化平台与市售质谱仪结合使用，通过实施新的和传统的电离方法，提高了复杂混合物中化合物的覆盖范围。该自动化平台的多功能性通过与来自两个不同供应商的质谱仪耦合来证明。使用电喷雾电离（ESI）、溶剂辅助电离（SAI）和基质辅助电离（MAI）采集标准品和复杂生物样品。
MS™ 原型自动化平台从 96 孔或 384 孔板以及表面采样。该平台通过更换 IonMax 源与赛默飞世尔科技的质谱仪接口，并通过对沃特世质谱仪进行少量的源入口修改与质谱仪接口。样品通过熔融石英或金属毛细管转移到电离区，在采集之间使用溶剂清洗毛细管。对于 ESI 和 SAI，通常将 1μL 样品溶液吸入毛细管管中，对于 ESI，通过施加电压于输送注射器筒来缓慢地将其分配到质谱仪入口附近，而对于 SAI，样品输送管插入入口而无需高压。对于 MAI，通常在吸入 0.1μL 样品溶液之前将 0.2μL 基质溶液吸入注射器中，然后在插入入口之前将其干燥。
对血管紧张素 I、维拉帕米、结晶紫和莠去津的混合物（代表肽、药物、染料和除草剂）进行 SAI、MAI 和 ESI 的比较研究表明，各种成分的电离效率存在很大差异。在 384 微孔板的孔中混合红霉素和阿奇霉素的溶液使用 MAI 和 ESI 以约 1 分钟/样品的速度进行质谱分析。此外，我们还报告了使用自动化 MAI 和 ESI 方法分析细菌提取物的情况。最后，通过直接分析薄层色谱（TLC）板上分离的染料和从牛肝组织切片表面提取的化合物，证明了自动化平台进行表面分析的能力。
原型多离子化自动化平台提供了用于 MAI 的固体基质引入，以及用于 ESI 或 SAI 的溶液引入。电离方法的组合扩展了有效电离的化合物类型，特别是对于复杂混合物非常有价值，如细菌提取物所示。虽然展示了将自动化多离子化平台与赛默和沃特世质谱仪耦合，但它应该可以与大多数商业质谱仪接口。
