Quality Control of Shampoo

Importance of the Topic

Quality control of personal care products such as shampoos is critical to ensure consumer safety, regulatory compliance, and consistent performance. Conventional wet-chemical methods for surfactant analysis are laborious, require extensive sample preparation and reagents, and are time-consuming and costly. A fast, reagent-free alternative can significantly improve laboratory efficiency and sustainability.

Objectives and Study Overview

This study aimed to develop and validate a visible-near infrared (Vis-NIR) spectroscopy method for the simultaneous quantification of key shampoo ingredients: sodium laureth sulfate (SLES), cocamidopropyl betaine (CABP), cocamidopropylamine oxide (CAW), cocamide diethanolamine (DEA), and carbopol. The goals were to assess method feasibility, establish calibration models, evaluate prediction accuracy, and compare analysis speed and running costs with traditional titration/HPLC methods.

Methodology and Instrumentation

No sample preparation or chemicals were required. Shampoos were measured in transflection mode over 400–2500 nm using a DS2500 Solid Analyzer equipped with a 1 mm gold diffuse reflector and a DS2500 Slurry Cup for sample positioning and cleaning. Spectral acquisition and multivariate model development were conducted with Vision Air Complete software. Calibration datasets were built by correlating NIR spectra with reference titration values for each analyte.

Main Results and Discussion

Calibration models exhibited strong predictive performance:

• SLES: R²=0.998, SECV≈0.14 %
• CABP: R²=0.996, SECV≈0.05 %
• CAW: R²=0.998, SECV≈0.06 %
• DEA: R²=0.998, SECV≈0.036 %
• Carbopol: R²=0.969, SECV≈0.41 %

Correlation diagrams demonstrated close agreement between NIR predictions and primary titration values, confirming method robustness for routine monitoring.

Benefits and Practical Applications

The Vis-NIR approach reduces analysis time to under one minute per sample and eliminates reagent consumption, cutting average annual running costs by over 85% compared to titration/HPLC workflows. Its high throughput and minimal maintenance make it ideal for in-process and final quality control in shampoos and other personal care formulations.

Future Trends and Possibilities

Advancements in portable and inline NIR instruments will enable real-time, on-line monitoring directly in production environments. Integration with machine learning algorithms and expanded spectral libraries can further enhance model accuracy across varied formulations. Coupling spectroscopy data with manufacturing execution systems will support fully automated process control and predictive maintenance.

Conclusion

Vis-NIR spectroscopy using the DS2500 Solid Analyzer offers a rapid, cost-effective, and sustainable alternative to traditional wet-chemical analyses for shampoo quality control. Its ability to deliver precise, simultaneous quantification of multiple surfactants and polymers without reagents or sample preparation positions it as a powerful tool for modern analytical laboratories and manufacturing lines.

Instrumentation Used

• DS2500 Solid Analyzer (400–2500 nm)
• DS2500 Slurry Cup
• Gold diffuse reflector, 1 mm pathlength
• Vision Air 2.0 Complete software