Quantitative analysis of 6 beta blockers on an LCMS-8045RX

Importance of the topic

Liquid chromatography tandem mass spectrometry (LC-MS/MS) methods for beta-adrenergic blocking agents (beta blockers) are essential because these compounds are both widely prescribed for cardiovascular conditions and subject to misuse in sport. Reliable, ultra‑trace analytical capability supports clinical toxicology, anti‑doping testing, forensic investigations and residue monitoring. High sensitivity, selectivity and robustness are required to confidently detect and quantify multiple beta blockers in complex biological matrices such as urine.

Objectives and study overview

This study developed and evaluated an ultra‑trace LC-MS/MS research method on a Nexera X3 coupled to an LCMS-8045RX for simultaneous quantification of six beta blockers (atenolol, nadolol, acebutolol, metoprolol, propranolol and carvedilol). Key goals were to achieve low limits of detection and quantification in both neat solvent (methanol) and a urine diluent (Sigmatrix), demonstrate linearity across a wide calibration range, and optimize throughput and signal‑to‑noise via automated MRM optimization.

Methodology and instrumentation

• Sample preparation: Primary standards prepared at 1 mg/mL in LCMS‑grade methanol and diluted in methanol or Sigmatrix urine diluent to produce calibration series spanning 0.010–100 ng/mL.
• Chromatography: Shim-pack Velox Biphenyl column (2.7 µm, 2.1 × 100 mm). Mobile phases: A = 5 mM ammonium formate + 0.1% formic acid in water; B = 5 mM ammonium formate + 0.1% formic acid in 1:1 methanol:acetonitrile. Flow rate 0.6 mL/min, column temperature 40 °C, injection volume 1 µL. Gradient produced short retention times and a high‑organic flush at run end to maintain column integrity.
• Mass spectrometry: Electrospray ionization (ESI) in positive ion mode with multiple reaction monitoring (MRM). LabSolutions Connect MRM automated optimization was used to maximize signal‑to‑noise. Reported source and gas parameters include nebulizing gas ~7 L/min, heating gas flow ~14 L/min, drying gas ~3 L/min, interface temperatures and desolvation/heat block settings as reported by the vendor.

Used instrumentation

• LC system: Nexera X3 (Shimadzu).
• Mass spectrometer: LCMS-8045RX (Shimadzu) with CoreSpray/ESI interface.
• Chromatographic column: Shim-pack Velox Biphenyl, 2.7 µm, 2.1 × 100 mm.
• Software: LabSolutions with Connect MRM optimization.

Main results and discussion

• Sensitivity: Limits of detection (LOD) of 0.010 ng/mL were achieved for all six analytes in both methanol and Sigmatrix urine diluent (signal‑to‑noise > 3 and accuracy within ±20% for the reported LOQ/LOD criteria).
• Quantification: Limits of quantification (LOQ) were reported at either 0.010 or 0.025 ng/mL depending on analyte and matrix; the calibration range covered 0.010–100 ng/mL.
• Linearity and precision: Excellent linearity was observed across the calibration range with correlation coefficients R2 typically ≥ 0.995 (values reported around 0.995–0.997). Accuracy across calibrants remained within ±20% for the study’s 17‑point calibration sets.
• Chromatography: Fast separations with retention times between ~1.04 min (atenolol) and ~3.05 min (carvedilol) enabled high throughput. The method provided baseline separation sufficient for MRM quantification in a short run time.
• MRM transitions: Each analyte was monitored using optimized precursor→product transitions (primary product ions reported per compound). Automated MRM optimization improved signal‑to‑noise and selectivity for each target analyte.
• Matrix performance: Comparable LODs between solvent and Sigmatrix urine diluent indicate strong method robustness against simple urine matrix effects at the tested diluent conditions; however, full validation in authentic urine samples and with internal standards would be required for regulated bioanalytical applications.

Benefits and practical applications

• Ultra‑trace capability (0.010 ng/mL LOD) supports sensitive anti‑doping screening, forensic toxicology, and research applications where very low concentrations must be measured.
• Short chromatographic cycle times improve laboratory throughput and sample throughput for screening programs.
• Use of automated MRM optimization simplifies method setup and helps ensure reproducible, high signal‑to‑noise transitions across multiple analytes.
• Method flexibility: compatibility with neat solvent and urine diluent makes the approach adaptable for both standard curve preparation and preliminary urine screening workflows.

Future trends and possibilities

• Extension to authentic biological matrices: full validation using real urine, plasma or serum with matrix‑matched calibrators and isotope‑labeled internal standards would increase method readiness for regulated testing.
• Broader analyte panels: adaptation to include additional beta blockers or metabolites to expand anti‑doping and forensic panels.
• High‑resolution MS and acquisition strategies: incorporation of HRMS could add confirmatory power and retrospective data mining capability.
• Miniaturization and microflow LC: reducing solvent consumption and increasing MS sensitivity through optimized flow regimes.
• Automated sample preparation: on‑line SPE or robotic workflows to improve reproducibility and reduce manual effort for high throughput labs.

Conclusion

The described LCMS-8045RX method delivers ultra‑trace detection and reliable quantification of six beta blockers with LODs at 0.010 ng/mL, strong linearity across 0.010–100 ng/mL, and rapid chromatographic separation. Automated MRM optimization and an optimized gradient provide high signal‑to‑noise and throughput suitable for research, anti‑doping screening and exploratory toxicology work. Further validation with real biological matrices and use of isotope‑labeled internal standards would be recommended for routine diagnostic or regulatory applications.

Reference

1. Pujos C., et al. Comparison of the analysis of Beta‑Blockers by different techniques. Journal of Chromatography B, 2009;877(32):4007–4014.
2. World Anti‑Doping Agency. World Anti‑Doping Code: International Standard — Prohibited List, 2021.