Fourier-Transform MS and Closed-Path Multireflection Time-of-Flight MS Using an Electrostatic Linear Ion Trap

An electrostatic linear ion trap (ELIT) has been configured to allow for the simultaneous acquisition of mass spectra via Fourier transform (FT) techniques (frequency measurement) and via time-of-flight (TOF; time measurement). In the former case, the time-domain image charge derived from a pick-up electrode in the field-free region of the ELIT is converted to frequency-domain data via Fourier transformation (i.e., FT-ELIT MS). In the latter case, the time difference between ion injection into the ELIT and ion detection after release from the ELIT using a microchannel plate (MCP) enables the acquisition of multireflection time-of-flight mass spectra (MR-TOF MS). The ELIT geometry facilitates the acquisition of both types of data simultaneously because the detection schemes are independent and do not preclude one another. The two MS approaches exhibit a degree of complementarity. Resolution increases much faster with time with the MR-TOF approach, for example, but the closed-path nature of executing MR-TOF in an ELIT limits both the <i>m</i>/<i>z</i> range and the peak capacity. For this reason, the FT-ELIT MS approach is most appropriate for wide <i>m</i>/<i>z</i> range applications, whereas MR-TOF MS can provide advantages in a “zoom-in” mode in which moderate resolution (<i>M</i>/Δ<i>M</i>_fwhm ≈ 10000) at short analysis times (10 ms) is desirable

Moriarty et al database ear mite treatment study

Data collected from field examinations of island foxes in this study, as well as lab analysis results (histopathology, immunology, mite counts, etc

Otitis and ceruminous gland hyperplasia (CGH) scores in a subset of Island foxes recaptured at t₃.

<p>Comparison between treated and untreated foxes at t₃, and between t₀ and t₃ within each group. Number of treated and untreated foxes at t₀ and t₃ (37, 33). Range of values for otitis and CGH shown in parentheses above each bar. Foxes excluded from analyses: three treated and two untreated foxes at t₀, one treated and untreated fox at t₃ (non-diagnostic biopsy), 18 treated and 22 untreated foxes at t₃ (not recaptured). ^a,b Significant difference (Mann-Whitney U test, p < 0.001). ^{c, d, e} Significant difference (Friedman test, p ≤ 0.007).</p

Scoring criteria: otoscopic assessment of mites and histopathologic assessment of otitis and ceruminous gland hyperplasia (CGH).

<p>Scoring criteria: otoscopic assessment of mites and histopathologic assessment of otitis and ceruminous gland hyperplasia (CGH).</p

IgG levels in Santa Catalina Island treated/untreated and uninfected/infected foxes, and Santa Cruz Island foxes.

<p>IgG level: a relative quantity of mite-specific antibody (determined by interpolation from a four-point calibration curve, see text for further explanation). Number of treated and untreated foxes (t₀: 59, 57; t₁: 38, 42; t₂: 24, 36 t₃: 40, 36); number of uninfected and infected foxes (t₀: 116; t₁: 31, 49; t₂: 25, 35 t₃: 42, 35); number of SCZ foxes (43). Range of values for IgG shown in parentheses above each bar. Foxes excluded from analyses: one untreated/infected fox at t₀ and one treated/uninfected fox at t₁ (missing IgG level). ^{a, b} Significant difference (Friedman test, p < 0.001). ^c Significant difference between SCZ foxes vs. SCA treated and untreated foxes at all capture events (Mann-Whitney U test, p ≤ 0.01), except for SCA treated foxes at t₃ (p = 0.6). ^{d, e, f} Significant difference (Mann-Whitney U test, p ≤ 0.01). ^{g, h} Significant difference (Friedman test, p ≤ 0.004). ⁱ Significant difference between SCZ foxes vs. SCA infected and uninfected foxes at all capture events (Mann-Whitney U test, p ≤ 0.001), except for SCA uninfected foxes at t₂ (p = 0.1) and t₃ (p = 0.9).</p

Ear mite prevalence and intensity of infection in treated and untreated Island foxes.

<p>Prevalence: number of foxes with mites/total number of foxes. Intensity of infection: median ear mite count. Number of treated and untreated foxes (t₀: 59, 58; t₁: 39, 42; t₂: 24, 36; t₃: 40, 36). Range of values for mite intensity shown in parentheses above each bar. Foxes excluded from analysis: one untreated fox at t₁ and t₂ (missing mite count), one untreated fox at t₃ (accidentally treated at t₂). ^{a, b, c} Significant difference (Pearson’s chi-square test, p < 0.001). ^d Significant difference (McNemar’s chi-square test, p< 0.001). ^{e, f, g} Significant difference (Mann-Whitney U test, p < 0.001). ^{h, i} Significant difference (Friedman test, p < 0.001, p = 0.02).</p