The present contribution describes analogies and differences between the quadrupolar ion trap (QIT) and the quadrupole mass analyzers, shows the potentialities of their combination in a single instrument and presents a review of applications of such a technology in different fields. The first section describes the quadrupole mass filter (QMF), outlining its principles of operation and the ion sorting procedure according to the use of oscillating electric fields inducing stable trajectories to the ions allowing them to reach the detector. Multiple quadrupole systems (normally triple quadrupoles) are then explained, showing their use in tandem mass spectrometry in space experiments (MS/MS-in-space). QIT principles of operation are then examined, pointing out that in this case the use of the same combination of oscillating electric fields takes advantage of unstable ion trajectories for their sorting. Substantially, analogies and differences between QMF and QIT come out, which consist in the fact that QMF is a scanning mass analyzer, whereas QIT is a sequential mass analyzer. In addition, the section underlines that QIT is capable to perform tandem mass spectrometry in time experiments (MS/MS-in-time). Later, the possibility to use a quadrupole as a trapping system with a prevailing dimension (linear ion trap [LIT]) is taken into consideration, and the possibility to combine both QMF and LIT in a single instrument, a QTrap mass spectrometer, is illustrated. In this frame, a lot more experiment types are possible with respect to both standalone triple quadrupoles and LIT, and they are described as well. Several combinations of these QTrap features can be used in information dependent acquisition (IDA) mode, allowing the high versatility of this instrumental configuration. The second section deals with a review of applications in different fields. These are organized by kind of QTrap and IDA features and cover different topics in biological, medical, agrochemical, nutritional and environmental fields.

中文翻译：

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离子扫描或离子捕获：为什么不能两者兼而有之？

目前的贡献描述了四极离子阱 (QIT) 和四极质量分析器之间的类比和差异，展示了它们在单个仪器中组合的潜力，并回顾了这种技术在不同领域的应用。第一部分描述了四极杆质量过滤器 (QMF)，概述了其操作原理和离子分选程序，该程序根据使用振荡电场诱导稳定的离子轨迹使其到达检测器。然后解释了多四极杆系统（通常是三重四极杆），展示了它们在空间实验（MS/MS-in-space）中的串联质谱分析中的用途。然后检查 QIT 的操作原理，指出在这种情况下，使用相同的振荡电场组合利用不稳定的离子轨迹进行分选。QMF和QIT之间的类比和区别在本质上是存在的，即QMF是扫描质量分析器，而QIT是顺序质量分析器。此外，该部分强调 QIT 能够在时间实验 (MS/MS-in-time) 中执行串联质谱分析。后来，考虑了使用四极杆作为具有主要尺寸的捕获系统（线性离子阱 [LIT]）的可能性，并说明了将 QMF 和 LIT 结合在单个仪器（QTrap 质谱仪）中的可能性. 在这个框架中，关于独立三重四极杆和 LIT 的更多实验类型是可能的，他们也被描述了。这些 QTrap 功能的多种组合可用于信息相关采集 (IDA) 模式，从而实现该仪器配置的高度通用性。第二部分涉及对不同领域应用程序的审查。这些按 QTrap 和 IDA 功能分类，涵盖生物、医学、农业化学、营养和环境领域的不同主题。