Fast, Easy, and Reliable Measurements of Liquid Samples Using Transmission FTIR

Significance of the Topic

Transmission FTIR is widely used in pharmaceutical quality control, but traditional liquid cells present several drawbacks: fragility, pathlength variability, leak risk, bubble interference, and high solvent consumption. The Agilent DialPath sampling module simplifies liquid sample measurement, improving reliability and throughput.

Objectives and Study Overview

This study compares the performance of the Agilent Cary 630 FTIR with the DialPath module against a conventional demountable transmission cell for quantifying simethicone according to USP43-NF38.

Methodology and Instrumentation

• Sample Preparation:
  Standard simethicone solutions (2 mg/mL) and control samples (81.2%, 114.0%, 100.7%) prepared per USP43-NF38; commercial capsule extracts were also prepared.
• Instrumentation:
  Agilent Cary 630 FTIR with a 500 µm DialPath module and Agilent Cary 630 FTIR with a traditional transmission cell (CaF2 windows, 500 µm spacer).
• Data Collection Parameters:
  Spectral range: 4000–650 cm−1; resolution: 2 cm−1; 64 scans; pathlength: 500 µm; background blank.
• Software and Analysis:
  Agilent MicroLab software automated module detection, absorbance measurement at ~1260 cm−1, and percentage concentration calculations.

Main Results and Discussion

• Linearity: The DialPath response was linear (R2=0.9997) across 0–190% simethicone.
• Accuracy: Recovery tests (5–15% spike) yielded mean recoveries around 100.4–100.5%.
• Precision: Repeatability study showed absorbance SD=0.0013 and concentration SD=0.34%.
• Comparative Quantification: Control sample accuracy was higher with DialPath (98.1–100%) versus transmission cell (97.4–98.8%).
• Commercial Samples: DialPath and cell results (101.3–102.4% vs 101.8–103.8%) met USP criteria (85–110%).
• Throughput and Resource Use: DialPath doubled sample throughput (40 vs 20 per hour), reduced sample volume (20 µL vs 5 mL), and minimized cleaning time and solvent waste.

Benefits and Practical Applications

• Improved reproducibility and ease of use, suitable for routine pharmaceutical analysis.
• Reduced sample and solvent consumption, leading to time and cost savings.
• Rapid module switching and automated data processing support compliance with pharmacopoeia standards and regulatory requirements.

Future Trends and Opportunities

• Integration of FTIR sampling accessories with automated platforms for high-throughput screening.
• Expansion to other viscous or sticky pharmaceutical formulations and complex matrices.
• Enhanced software features for advanced chemometric analysis and real-time quality control.
• Development of new sampling modules with variable pathlengths for broader concentration ranges.

Conclusion

The Agilent Cary 630 FTIR with the DialPath module offers a robust, accurate, and efficient approach for liquid pharmaceutical analysis. It outperforms traditional transmission cells in accuracy, precision, and resource efficiency, meeting global pharmacopoeial requirements and supporting streamlined QA/QC workflows.

References

• United States Pharmacopeia and National Formulary, USP43-NF38. Simethicone Emulsion, DocID: GUID-4965A93F-3617-485C-87B4-1DFBDF33EC3F_4_en-US.