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.

尽管通过液相色谱-串联质谱法（LC-MS / MS）广泛使用了电喷雾电离（ESI）定量神经肽，但该电离界面的电离和传输效率仍然很差。最近开发了一种新的名为UniSpray的大气压电离源并将其商业化。在这项研究中，评估了该新电离界面的LC-MS性能，并将其与ESI进行了比较，以定量7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）和准确性和精度。另外，评估了人类沉淀的血浆和大鼠微量透析液的基质效应，以及三种增压剂对七个神经肽电离的影响。对于所有七个神经肽，在最佳毛细管/接触器电压下，UniSpray电离导致信号强度高出四到八倍。另一方面，使用UniSpray源时，S / N值仅增加不超过两倍。此外，UniSpray电离导致某些神经肽向低电荷态转变。通过柱后输注设置评估基质效应，导致ESI和UniSpray之间的输注曲线不同。UniSpray获得的神经肽的电荷状态分布与ESI高度可比。最终，增压剂对神经肽电离的作用倾向于与两种电离源有关的肽依赖性。