Analysis of a Fixed–Dose Combination Drug Using the Agilent 1290 Infinity II Evaporative Light Scattering Detector

Importance of the Topic

Evaporative light scattering detection (ELSD) is essential for analyzing semivolatile and nonvolatile compounds that lack UV chromophores. In pharmaceutical quality control, many fixed-dose combination drugs contain active ingredients at widely differing concentrations. A detector with an extended dynamic range simplifies analysis by quantifying both high- and low-dose components in a single injection.

Objectives and Study Overview

This study evaluates the Agilent 1290 Infinity II ELSD’s performance in quantifying a fixed-dose combination drug containing paracetamol, vitamin C, caffeine and chlorphenamine across an 80:1 concentration ratio. Results are directly compared with those from a conventional ELSD under identical chromatographic conditions.

Methodology

Sample preparation involved opening two capsules, dissolving contents in water, ultrasonic extraction, filtration and serial dilution (1:10–1:50). Chromatographic separation was performed on a ZORBAX Eclipse Plus C18 column (4.6×100 mm, 5 µm) at 40 °C, using a water–acetonitrile gradient with 0.1% trifluoroacetic acid at 1 mL/min. Detection employed both the Agilent 1290 Infinity II ELSD and a conventional ELSD; UV–DAD monitoring at 254 nm served as a reference.

Instrumentation

• Agilent 1290 Infinity II Flexible Pump
• Agilent 1290 Infinity II Multisampler
• Agilent 1290 Infinity II Diode Array Detector
• Agilent 1290 Infinity II Evaporative Light Scattering Detector (G7102A)
• Agilent 1290 Infinity Evaporative Light Scattering Detector (G4261B)

Results and Discussion

The 1290 Infinity II ELSD demonstrated a linear response over four orders of magnitude—ten times wider than a conventional ELSD. A single injection of an undiluted sample resolved high-dose (20,000 ng/µL paracetamol, 15,000 ng/µL vitamin C) and low-dose (250 ng/µL chlorphenamine, 2,500 ng/µL caffeine) analytes with area RSDs below 3% (except chlorphenamine at 17.8%, still quantifiable at S/N > 16). Paracetamol calibration (400–2,000 ng/µL) yielded R² = 0.9996; chlorphenamine (5–25 ng/µL) gave R² = 0.9969. By contrast, the conventional ELSD required multiple dilutions and failed to quantify low-level analytes accurately in one run.

Practical Benefits and Applications

Automatic gain control and the enhanced dynamic range of the 1290 Infinity II ELSD streamline method development and improve sample throughput in pharmaceutical analysis. A single detector can replace multiple injections or detectors for fixed-dose combinations.

Future Trends and Applications

Future developments may integrate high dynamic range ELSDs with UHPLC–MS workflows and advanced signal processing to extend detection capabilities to complex matrices and nonvolatile analytes. Such enhancements will further boost efficiency in drug development and quality control.

Conclusion

The Agilent 1290 Infinity II ELSD offers a significant performance advantage over conventional ELSDs, providing a four-order dynamic range that enables accurate quantification of compounds across an 80:1 concentration ratio in a single injection. This advance reduces analysis time and simplifies workflows in pharmaceutical laboratories.

References

• Schuhn B. Analysis of a Fixed–Dose Combination Drug Using the Agilent 1290 Infinity II Evaporative Light Scattering Detector. Agilent Technologies Inc., 2015.