Simultaneous analysis of anionic, amphoteric and non-ionic surfactants using ultra-high speed LC-MS/MS

Importance of the topic

Surfactants are key components in household and industrial products such as detergents, shampoos and soaps. Monitoring anionic, amphoteric and non-ionic types simultaneously is crucial for environmental and quality control applications. The diversity of surfactant chemistries demands a rapid and sensitive analytical approach.

Objectives and Overview of the study

The study aimed to develop a single ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method capable of separating and quantifying representative anionic, amphoteric and non-ionic surfactants. Key objectives were high throughput, broad coverage and low detection limits.

Methodology

Standards of linear alkylbenzene sulfonates (LAS C10–C14), betaine amphoterics (C10, C12, C14) and heptaethyleneglycoldodecylether (HEDE) were prepared in water/acetonitrile. Chromatographic separation was achieved on a YMC-Triart C8 column (100×2.0 mm, 1.9 μm) at 40 °C with a binary gradient of 10 mM ammonium acetate (A) and 10 mM ammonium acetate/acetonitrile/isopropanol (1/4/5) (B). The flow rate was 0.3 mL/min and injection volume 10 μL. Electrospray ionization with ultra-fast polarity switching (15 ms) was used in multiple reaction monitoring (MRM) mode. Calibration curves covered 0.5–500 ppb with r2 values above 0.997.

Instrumentation

• UHPLC system Nexera MP (Shimadzu)
• Triple quadrupole mass spectrometer LCMS-8040 (Shimadzu)
• YMC-Triart C8 column (100 mm×2.0 mm, 1.9 μm)
• ESI source with ultra-fast polarity switching up to 555 transitions/sec

Main results and Discussion

All nine surfactants were baseline-resolved within 2.5 minutes and detected in a 5-minute total cycle time. Linearity was excellent across the tested ranges. Application to 1000× diluted household samples revealed LAS concentrations of 5–6 ppm in liquid soap and 35–75 ppm of selected surfactants in kitchen detergent. High-speed switching ensured simultaneous detection of positive and negative ions with high sensitivity.

Benefits and Practical Applications

• Single-run analysis of multiple surfactant classes
• High throughput for routine screening
• Low detection limits suitable for environmental monitoring
• Applicable to quality control in consumer products

Future trends and Potential Applications

Future work may extend this approach to a wider range of surfactant chemistries and environmental matrices, integrate high-resolution mass spectrometry for structural elucidation, and develop miniaturized or on-site systems for rapid field analysis.

Conclusion

A rapid UHPLC-MS/MS method with ultra-fast polarity switching was established for simultaneous quantification of anionic, amphoteric and non-ionic surfactants. The method demonstrated high resolution, sensitivity and linearity, and was successfully applied to real-world household samples.

References

• Matsumoto K, Watanabe J, Iida J. Simultaneous analysis of anionic, amphoteric and non-ionic surfactants using ultra-high speed LC-MS/MS. ASMS 2012; TP31-612. Shimadzu Corporation; 2012.