Ion Behavior in an Electrically Compensated Ion Cyclotron Resonance Trap.

We recently described a new electrically compensated trap in FT ion cyclotron resonance mass spectrometry and developed a means of tuning traps of this general design. Here, we describe a continuation of that research by comparing the ion transient lifetimes and the resulting mass resolving powers and signal-to-noise (S/N) ratios that are achievable in the compensated vs. uncompensated modes of this trap.

Characterization of currently marketed heparin products: reversed-phase ion-pairing liquid chromatography mass spectrometry of heparin digests.

Here we report results from the analyses by enzymatic digestion and reversed-phase ion-pairing liquid chromatography mass spectrometry (RPIP-LC-MS) of active pharmaceutical ingredient (API) unfractionated heparins (UFHs) from six different manufacturers and one USP standard sample. We employed a reverse phase ion-pairing chromatography method using a C(18) column and hexylamine as the ion-pairing reagent with acetonitrile gradient elution to separate disaccharides generated from the digestion of the heparins by lyase I and III (E.C.

A tuning method for electrically compensated ion cyclotron resonance mass spectrometer traps.

We describe a method for tuning electrically compensated ion cyclotron resonance (ICR) traps by tracking the observed cyclotron frequency of an ion cloud at different oscillation mode amplitudes. Although we have used this method to tune the compensation voltages of a custom-built electrically compensated trap, the approach is applicable to other designs that incorporate electrical compensation. To evaluate the effectiveness of tuning, we examined the frequency shift as a function of cyclotron orbit size at different z-mode oscillation amplitudes.

An electrically compensated trap designed to eighth order for FT-ICR mass spectrometry.

We present the design, guided by theory to eighth order, and the first evaluation of a Fourier transform ion cyclotron resonance (FT-ICR) compensated trap. The purpose of the new trap is to reduce effects of the nonlinear components of the trapping electric field; those nonliner components introduce variations in the cyclotron frequency of an ion depending on its spatial position (its cyclotron and trapping mode amplitudes). This frequency spread leads to decreased mass resolving power and signal-to-noise.