Quantification of active ingredients in shampoo using near-infrared spectroscopy (NIR)

Significance of the Topic

Near-infrared spectroscopy offers a rapid, non-destructive alternative to conventional chromatographic methods for quantifying multiple active and preservative components in complex shampoo matrices. Its minimal sample preparation, lack of chemical reagents, and low waste generation make it an attractive tool for routine quality control.

Objectives and Study Overview

The study targeted simultaneous quantification of a preservative (A) and two actives (B, C) in liquid shampoo using NIRS. A calibration model was developed and validated against reference laboratory values to assess accuracy and precision.

Methodology

Spectral data were collected from 48 shampoo samples with varying concentrations of components A, B, and C.

• Spectra were recorded on a Metrohm NIRS XDS RapidLiquid Analyzer with a 0.5 mm quartz cuvette and spacer.
• Data preprocessing employed second derivative transformation to enhance spectral features.
• Quantitative models were built using partial least squares regression, optimizing the number of factors for each analyte.

Used Instrumentation

• Metrohm NIRS XDS RapidLiquid Analyzer (2.921.1410)
• NIRS Quartz Cuvette, Open Top 0.5 mm (6.7401.110)
• NIRS Spacer for Quartz Cuvette 0.5 mm (6.7403.110)
• Vision Air 2.0 Complete software (6.6072.208)

Main Results and Discussion

• Preservative A: SEC 0.111% over 0–4%, using 4 PLS factors.
• Active ingredient B: SEC 0.147% over 0–4%, using 4 PLS factors.
• Active ingredient C: SEC 0.026% over 0–1%, using 2 PLS factors.

The strong correlation between predicted and reference values confirms the method's reliability for multi-constituent analysis in under one minute per sample.

Benefits and Practical Applications

• Rapid analysis with results in less than 60 seconds.
• Simultaneous quantification of multiple ingredients in a single measurement.
• No solvents or disposable columns, reducing operational costs and waste.
• Ability to detect out-of-specification batches promptly in manufacturing and QA/QC environments.

Future Trends and Opportunities

• Expansion to other personal care and detergent formulations.
• Integration with process analytical technology (PAT) for real-time monitoring.
• Development of portable or inline NIR sensors for on-site quality control.
• Enhanced chemometric techniques for improved model robustness.

Conclusion

Near-infrared spectroscopy provides an efficient and sustainable alternative to HPLC for multi-constituent quantification in shampoos, combining speed, accuracy, and cost savings. This method supports streamlined quality control workflows and aligns with green analytical chemistry principles.

Reference

NIR Application Note NIR-050, Version 1, October 2017