Improved Reproducibility for Acetaminophen Assay USP Monograph Using MaxPeak™ Premier Columns after Modernization to 2.5 μm Particles

Importance of the Topic

The USP monograph for acetaminophen ensures consistent evaluation of drug purity, potency, and identity, underpinning quality control in pharmaceutical laboratories. Modernizing such methods to smaller particle sizes can shorten analysis time and reduce solvent consumption, but requires robust column performance to maintain reproducibility.

Objectives and Study Overview

This study assesses reproducibility of acetaminophen quantitation in cold and cough medicine using traditional stainless-steel columns versus Waters MaxPeak Premier columns after modernization to 2.5 µm particles according to USP <621> guidelines.

Methodology

Three solutions (standard, system suitability, and OTC cough syrup sample) were prepared at 0.2 mg/mL acetaminophen in 45/55 methanol/water. Five injections per solution (n=15) were performed under isocratic conditions (45% MeOH/55% H2O), flow rate 0.42 mL/min, injection volume 0.8 µL, and sample temperature 10 °C.

Used Instrumentation

• ACQUITY H-Class Plus UPLC with PDA detector (254 nm)
• XBridge BEH C18, 2.1×100 mm, 2.5 µm and XBridge Premier BEH C18, 2.1×100 mm, 2.5 µm columns
• Empower 3 chromatography data system

Main Results and Discussion

The MaxPeak Premier column exhibited markedly lower variability compared to stainless-steel columns:

• Retention time %RSD: 0.09% vs. 1.59%
• Peak area %RSD: 0.03% vs. 0.91%
• Assay bias: 93.0% vs. 93.4%

Both columns met USP criteria (tailing ≤2.0; %RSD ≤2.0%; assay 90–110%), but Premier columns delivered tighter overlays and eliminated retention shifts attributed to metal-analyte interactions.

Benefits and Practical Applications

• Enhanced reproducibility reduces retesting and regulatory risks
• Shorter runtimes and lower solvent use after modernization
• Greater confidence in batch release testing by minimizing non-specific adsorption

Future Trends and Opportunities

Trends include wider adoption of sub-2.5 µm column formats, expanded use of surface-passivating technologies to mitigate metal adsorption, and integration of automated method transfer and monitoring tools, further streamlining USP monograph modernization across diverse analytes.

Conclusion

Modernization of USP acetaminophen assays to 2.5 µm particles per Chapter <621> enhances throughput and efficiency. MaxPeak Premier columns further improve precision and reproducibility by reducing metal-analyte interactions, making them an optimal choice for pharmaceutical quality control.

References

• USP General Chapter <621>, accessed April 25 2022
• Berthelette K. et al., Waters Application Note 720007872, 2023
• USP Monograph: Acetaminophen and related compounds in oral solution, accessed April 25 2022