Mass spectrometry method using filtered noise signal

A mass spectrometry method, including the steps of:

• (a) introducing ions in a trapping region bounded by a ring electrode and a pair of end electrodes separated along a central axis, while applying a combined signal to at least a subset of the ring electrode and the end electrodes to establish a combined trapping field in said trapping region, wherein the combined trapping field includes a three-dimensional guadrupole trapping field component, wherein the combined trapping field is capable of trapping one or more selected ones of the ions in the trapping region and ejecting ions other than said selected ones of the ions from the trapping region, and wherein the combined signal comprises a fundamental trapping voltage signal and a filtered noise signal;
• and
• (b) after step (a), changing one or more parameters of the combined signal to sequentially excite the selected ones of the ions for the detection.

A mass spectrometry method, including the steps of:

• (a) introducing ions in a trapping region defined by a set of electrodes, while applying a combined signal to the electrodes thereby establishing a combined field capable of trapping one or more selected ones of the ions in the trapping region and ejecting ions other than said one or more selected ones of the ions from the trapping region, wherein the combined signal comprises a trapping voltage signal and a filtered noise signal;
• and
• (b) after step (a), terminating application of the filtered noise signal, and changing one or more parameters of the trapping voltage signal to sequentially excite the selected ones of the ions for detection.