The Waters ACQUITY QDa is a compact single-quadrupole mass detector designed to bring mass-spectrometric selectivity into routine HPLC and UPLC workflows. It provides a mass range of 30–1250 m/z, positive and negative electrospray ionization, and Full Scan and Single Ion Recording (SIR) acquisition. Its design focuses on simplified operation without the extensive tuning traditionally associated with LC-MS systems.
The QDa integrates into an LC stack similarly to a conventional optical detector and can be used with supported Waters ACQUITY UPLC, ACQUITY UPLC H-Class, ACQUITY Arc, and other LC platforms. Automatic mass-calibration verification and system health checks simplify routine operation and make MS detection accessible to QA/QC and analytical laboratories.
Mass Analyzer
The ACQUITY QDa uses a single quadrupole mass analyzer.
- Mass range: 30–1250 m/z
- Nominal resolution: 0.7 Da FWHM
- Mass-scale verification acceptance: approximately ±0.2 Da
- Maximum scan speed: 10,000 Da/s
This provides additional selectivity and peak-identification information compared with optical detection alone.
Acquisition Modes
Full Scan
Full Scan is suitable for:
- molecular-ion confirmation,
- sample screening,
- basic mass spectral information,
- complementing UV/PDA data with m/z information.
SIR
Single Ion Recording selectively monitors specific m/z values and supports improved sensitivity and selectivity for targeted assays.
Typical uses include:
- routine quantitation,
- targeted impurity monitoring,
- identity confirmation,
- defined-compound screening.
Electrospray Ionization
The QDa incorporates a pre-aligned ESI source supporting positive and negative ion modes.
Capillary-voltage ranges:
- positive: 0.3–1.5 kV
- negative: 0.3–0.8 kV
Cone voltage is adjustable from approximately 0–100 V.
LC Flow Compatibility
- Maximum LC flow: 2.0 mL/min
- Optimum performance range: approximately 0.3–0.8 mL/min
- Operation below approximately 0.2 mL/min is not optimal for the original QDa.
This enables direct connection to conventional analytical LC workflows without routine flow splitting.
Nitrogen Requirements
- Gas: dry, oil-free nitrogen
- Minimum purity: 95%
- Supply pressure: 6.5–7 bar
- Typical consumption: approximately 1300 L/h.
Software
The ACQUITY QDa can be controlled through:
- Waters Empower™
- Waters MassLynx™
This enables chromatographic and mass-detection data to be handled within a common workflow.
Typical Applications
- Pharmaceutical analysis
- Impurity analysis
- QA/QC
- Peak identity confirmation
- LC-MS screening
- Food analysis
- Environmental analysis
- Veterinary pharmaceuticals
- Small molecules
- Peptides
- Small biotherapeutics
- Metabolites
- Reaction monitoring
- Orthogonal detection alongside UV/PDA
