Terephthalic, Benzoic and p-Toluic Acids Using Acclaim Trinity P1

Significance of the Topic

Monitoring acidic degradation products in oral care formulations is critical for ensuring product safety and effectiveness. Benzoic acid, p-toluic acid and terephthalic acid can arise from excipient breakdown or raw material impurities. Rapid and reliable separation of these compounds supports quality control in mouthwash manufacturing, minimizes regulatory risk and protects consumer health.

Objectives and Study Overview

This study aimed to develop a fast isocratic chromatographic method for simultaneous determination of benzoic, p-toluic and terephthalic acids in mouthwash. The approach leverages mixed-mode retention to achieve baseline separation of all three analytes in under four minutes, streamlining routine analysis in QA/QC laboratories.

Methodology and Used Instrumentation

Chromatographic method employed a Thermo Scientific Acclaim Trinity P1 column (3.0 × 150 mm, 3.03 μm) operated at 25 °C with a flow rate of 0.5 mL/min. Mobile phase consisted of acetonitrile, 100 mM formic acid (pH 3.5) and water under isocratic conditions. Detection combined diode array UV monitoring at 220 nm for benzoic and p-toluic acids with conductivity detection using a Thermo Scientific Dionex CSRS 300 suppressor (external water 1.0 mL/min; 8 mA). Sample injections of 5 μL were made from standards prepared in mobile phase.

Main Results and Discussion

The mixed-mode column achieved clear resolution of all three acids within a four-minute window. At pH 3.5, benzoic and p-toluic acids remain largely neutral and are retained via hydrophobic interactions, while terephthalic acid is partially ionized and elutes distinctly due to ionic interactions. Conductivity detection provided sensitive, interference-free quantitation of terephthalic acid, while UV detection delivered sharp peaks for benzoic and p-toluic acids. Method precision and peak shapes met industry standards for routine quality testing.

Benefits and Practical Application

• Rapid throughput: analysis cycle under four minutes per injection
• Mixed-mode selectivity: robust separation of neutral and ionized acids
• Dual detection: UV and conductivity enhance sensitivity and specificity
• Simple isocratic operation: reduced solvent consumption and method complexity

Ideal for regular monitoring of acidic preservatives and impurities in oral care products, this method supports compliance with pharmacopeial and regulatory guidelines.

Future Trends and Potential Applications

Emerging directions include coupling this workflow with mass spectrometry for structural confirmation of unknown impurities, extending mixed-mode methods to other consumer products and integrating automated on-line sample preparation to boost laboratory efficiency. Continued development of novel stationary phases may further shorten run times and improve selectivity for complex matrices.

Conclusion

The presented isocratic mixed-mode chromatography method enables fast, reliable and sensitive determination of benzoic, p-toluic and terephthalic acids in mouthwash. Its simplicity and performance make it a valuable tool for quality control in the oral care industry.

References

1. Thermo Fisher Scientific Application Note PB20627_E, 2012
2. Thermo Fisher Scientific Application Note PB20856_E, 2013