High amplitude short time excitation: A method to form and detect low mass product ions in a quadrupole ion trap mass spectrometer

Abstract

Collision induced dissociation (CID) in a quadrupole ion trap mass spectrometer using the conventional 30 ms activation time is compared with high amplitude short time excitation (HASTE) CID using 2 ms and 1 ms activation times. As a result of the shorter activation times, dissociation of the parent ions using the HASTE CID technique requires resonance excitation voltages greater than conventional CID. After activation, the rf trapping voltage is lowered to allow product ions below the low mass cut-off to be trapped. The HASTE CID spectra are notably different from those obtained using conventional CID and can include product ions below the low mass cut-off for the parent ions of interest. . During CID, the internal energy of a parent ion is increased through inelastic collision(s) with a target gas, resulting in the dissociation of parent ions. CID is the result of two distinct events; parent ion activation (collisional activation) and parent ion dissociation [3]. The appearance of an MS/MS spectrum, both product ion formation and abundance, is a function of the amount of energy deposited into the parent ion during the activation period [4,5]. Activation times for CID in rf trapping instruments typically range between 10 and 50 ms; however, CID can be accomplished using much shorter activation times in these instruments [6].For rf trapping instruments, the Mathieu parameters q z , (proportional to the applied fundamental ac rf voltage), and a z , (proportional to the applied dc voltage) determine if ions of a given mass-to-charge will be trapped. Typically, and in these experiments, rf trapping instruments are operated at a z ϭ 0, so theoretically ions with q z values from 0 to 0.908 are trapped. As the mass-to-charge value of an ion increases, its q z value decreases. Thus, the mass-to-charge value corresponding to a q z value of 0.908 is the minimum mass-to-charge value of ions trapped and is termed the low mass cut-off (LMCO).Each ion held by the trapping field exists in a pseudo potential well with the well depth proportional to the q z for each mass-to-charge value. Hence, smaller mass-tocharge ions, which have larger q z values, exist in deeper wells than larger mass-to-charge ions, which have smaller q z values [7]. To implement CID, a q z value is selected that allows the kinetic energy of the parent ion to increase via power absorption from a supplementary resonance excitation voltage without exceeding the pseudo potential well depth. Typical q z values for CID in quadrupole ion traps range from 0.2 to 0.3 and supplementary resonance excitation voltages with amplitudes greater than 1 V are not generally utilized [8]. A trade-off in the selection of the q z value for CID is that product ions with mass-to-charge values below the LMCO will not be trapped. This means that product ions with mass-to-charge values less than ϳ25-30% of the parent ion mass-to-charge are not observed in the MS/MS spectrum.Previous research conducted using "fast excitation" CID has shown that collisional activation can be accom-

Tandem mass spectrometry identifies many mouse brain O -GlcNAcylated proteins including EGF domain-specific O -GlcNAc transferase targets

“…The AMT-GalNAz tag allowed CID to detect at least two of the three major oxonium ions from intact sugars (Fig. S3) despite the one-third low molecular-weight cutoff rule (23). Compared with CID, HCD consistently detected the three major diagnostic ions with higher mass accuracy and generally higher intensity (Fig.…”

Dynamic collision-induced dissociation (DCID) in a quadrupole ion trap using a two-frequency excitation waveform: I. Effects of excitation frequency and phase angle

“…The DCID process could then be followed by the mass acquisition scan in the normal fashion. This approach would be very similar to the HASTE experiments described°by°Glish°and°coworkers° [16],°except°for°the dynamic nature of energy deposition.…”

“…In selected applications, conventional on-resonance excitation can be slow relative to the timescale of fast separation methods, which can limit the sampling frequency or number of data points per chromatographic peak. Therefore, fragmentation procedures that can reduce the timeframe required for tandem mass spectra acquisition are desirable [15][16][17].…”

Theoretical Study of Dual-Direction Dipolar Excitation of Ions in Linear Ion Traps

“…To address the above issues, several methods for increasing the ion internal energy in ITs have been investigated and reported over the past decades [20][21][22][23][24]. The first method is to increase the ion kinetic energy, which is achieved by employing a highamplitude AC signal at relatively high q u value for ion activation with a short time followed by an ion trapping period at a low q u value, such as pulsed Q dissociation (PQD) [20], high amplitude short time excitation (HASTE) [21] and pulsed q dynamic CID [22].…”

“…The first method is to increase the ion kinetic energy, which is achieved by employing a highamplitude AC signal at relatively high q u value for ion activation with a short time followed by an ion trapping period at a low q u value, such as pulsed Q dissociation (PQD) [20], high amplitude short time excitation (HASTE) [21] and pulsed q dynamic CID [22]. The second is to increase the ion initial kinetic energy by heating the buffer gas, termed as thermally assisted collisioninduced dissociation (TA-CID) [23].…”