High throughput analysis of anion surfactant using ultra-high speed LC-MS/MS and 1 mm inside diameter column

Importance of the Topic

The analysis of anionic surfactants such as linear alkylbenzene sulfonates (LAS) is critical for environmental monitoring, industrial quality control, and regulatory compliance. Rapid, sensitive, and high‐throughput methods enable laboratories to process large sample sets efficiently while maintaining analytical precision and accuracy.

Study Objectives and Overview

This study aimed to develop and validate an ultra‐fast LC‐MS/MS method for the quantification and screening of C10–C14 LAS homologues. By employing a 1 mm internal diameter column coupled with a high‐speed triple quadrupole mass spectrometer, the authors sought to achieve sub‐minute separations and high sensitivity for trace‐level detection in aqueous matrices.

Methodology and Instrumentation Used

• UHPLC System: Nexera MP equipped with SIL‐30AC MP autosampler featuring ultrafast injection, ultralow carryover, and capacity for 2304 samples.
• Column: Unison UK‐C18 HT, 1 mm i.d. × 50 mm, 3 µm particle size.
• Mass Spectrometer: LCMS‐8030 triple quadrupole with rapid polarity switching (15 ms) and scanning up to 15 000 u/s.
• Chromatography: Binary gradient using 10 mM ammonium acetate (A) and acetonitrile (B), flow rates adjusted between 0.15 and 0.5 mL/min for high‐throughput conditions.
• Detection: Negative‐ion electrospray MRM transitions (quantitative Q1/Q3 and qualifier Q1/Q3 pairs) for each LAS homologue; precursor ion scan for m/z 183 screening.

Main Results and Discussion

Under conventional UHPLC conditions, individual isomers of LAS C10–C14 were fully resolved within 7 min. Recoveries in spiked tap water (20 ppb) ranged from 101.9% to 108.1%, demonstrating minimal matrix effects.

Optimized high‐throughput conditions achieved single‐peak separation of all LAS homologues in under 1 min. The total cycle time per injection was approximately 2 min. Calibration curves exhibited excellent linearity (R2 > 0.996) over 0.1–40 ppb, and repeatability at 0.5 ppb showed RSDs below 7.5%.

Precursor ion scanning at speeds up to 3750 u/s provided sharp chromatographic peaks and accurate mass assignments, confirming that ultra‐fast scanning did not compromise mass accuracy.

Benefits and Practical Applications

• High throughput: Enables rapid processing of large sample batches with minimal downtime.
• High sensitivity: Detection limits down to 0.1 ppb facilitate trace analysis in environmental and wastewater monitoring.
• Robustness: Matrix effects in tap water were negligible, supporting direct analysis of complex samples.

Future Trends and Applications

Continued miniaturization of columns and further acceleration of mass spectrometer scan rates will push the boundaries of throughput and sensitivity. Integration with automated sample preparation and real‐time data processing platforms could enable fully unattended monitoring in environmental and industrial settings. Additionally, expanding precursor ion screening to other surfactant classes and polar contaminants may broaden the utility of ultra‐fast LC‐MS/MS workflows.

Conclusion

The combination of a 1 mm i.d. column with an ultra‐fast LCMS‐8030 system delivers sub‐minute separation and reliable quantification of LAS homologues. This method offers high throughput, excellent sensitivity, and robust performance in aqueous matrices, making it a valuable tool for environmental and industrial analytics.

Reference

1) J. Watanabe et al., 56th ASMS Conference, LCMS I (WP)-295 (2008).