Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information (FASC), Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, 1090 Brussels, Belgium; Department of Analytical Chemistry, Applied Chemometrics and Molecular Modelling (FABI), Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, 1090 Brussels, Belgium.
Waters Belgium, Brusselsesteenweg 500, 1731 Zellik, Belgium.
J Chromatogr A. 2020 Sep 27;1628:461462. doi: 10.1016/j.chroma.2020.461462. Epub 2020 Aug 11.
Despite the extensive use of electrospray ionization (ESI) for the quantification of neuropeptides by liquid chromatography-tandem mass spectrometry (LC-MS/MS), poor ionization and transmission efficiency are described for this ionization interface. A new atmospheric pressure ionization source, named UniSpray, was recently developed and commercialized. In this study, the LC-MS performance of this new ionization interface is evaluated and compared with ESI for the quantification of seven neuropeptides. Besides comparison of signal intensities and charge state distributions, also signal-to-noise (S/N) ratios and accuracy and precision were assessed. Additionally, matrix effects of human precipitated plasma and rat microdialysate were evaluated as well as the effect of three supercharging agents on the ionization of the seven neuropeptides. UniSpray ionization resulted in signal intensities four to eight times higher at the optimal capillary/impactor voltage for all seven neuropeptides. S/N values at the other hand only increased by not more than a twofold when the UniSpray source was used. Moreover, UniSpray ionization resulted in a shift towards lower charge states for some neuropeptides. Evaluation of the matrix effects by a post-column infusion set-up resulted in different infusion profiles between ESI and UniSpray. The charge state distributions of the neuropeptides obtained with UniSpray are highly comparable with ESI. Finally, the effect of the supercharging agents on the ionization of the neuropeptides tends to be peptide-dependent with both ionization sources.
尽管电喷雾电离（ESI）在液相色谱-串联质谱（LC-MS/MS）中广泛用于神经肽的定量，但这种离子化接口的电离和传输效率较差。最近开发并商业化了一种名为 UniSpray 的新型大气压离子源。在这项研究中，评估了这种新的离子化接口的 LC-MS 性能，并将其与 ESI 进行了比较，以定量七种神经肽。除了比较信号强度和电荷状态分布外，还评估了信噪比（S/N）比值以及准确性和精密度。此外，还评估了人沉淀血浆和大鼠微透析液的基质效应，以及三种超荷电试剂对七种神经肽电离的影响。对于所有七种神经肽，在最佳毛细管/撞击器电压下，UniSpray 离子化导致信号强度提高了四到八倍。另一方面，当使用 UniSpray 源时，S/N 值仅增加了一倍。此外，UniSpray 离子化导致一些神经肽的电荷状态向低电荷状态转移。通过柱后输注装置评估基质效应会导致 ESI 和 UniSpray 之间的输注曲线不同。用 UniSpray 获得的神经肽的电荷状态分布与 ESI 高度可比。最后，两种离子源上超荷电试剂对神经肽电离的影响似乎都取决于肽。
