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Instrument families

OpenARaw's corpus covers two Agilent instrument families, both under the modern AcqData MassHunter directory layout:

Q-TOF​

Quadrupole time-of-flight instruments (models G6540B, G6550A confirmed in the validation corpus). Q-TOF acquisitions can carry profile data, centroid data, or both, and typically run Auto-MS/MS (data-dependent acquisition): MS1 survey scans interleaved with MS2 scans against automatically selected precursors.

  • analyzer on yielded spectra is Analyzer::TOFMS.
  • MS2 spectra carry a real target_mz precursor - see Scan data.
  • MSMassCal.bin is present, holding per-scan calibration coefficient traceability (already applied upstream - see MSMassCal.bin).

QQQ​

Triple-quadrupole instruments (model G6410A confirmed in the validation corpus) running targeted MRM (multiple reaction monitoring) acquisitions: a fixed list of precursor/fragment transitions cycled repeatedly through the run.

  • analyzer on yielded spectra is Analyzer::TQMS.
  • Every scan is effectively MS2; there is no isolation-window target_mz in the Q-TOF sense, so precursor identity is carried as precursor_native_id (mrm_channel=<id>) instead - see Scan data.
  • MSMassCal.bin is absent - QQQ instruments don't use TOF-style dynamic mass recalibration.

How the reader tells them apart​

The reader does not read the instrument model string. It infers the family from MSScan.bin's record stride (>= 220 bytes indicates Q-TOF; QQQ records use a shorter 186- or 196-byte stride) - see MSScan.bin for the full stride table. This heuristic has held across every corpus file tested; if you encounter a .d directory it misclassifies, please open an issue.