Highly sensitive method for determination of Ethanolamine in water as per ASTM D-7599 by LCMS-8045

Significance of the Topic

Ethanolamines are widely used in personal care products, industrial processes and gas treatment. Their bifunctional structure makes them effective emulsifiers and surfactants. However, their presence in water at trace levels raises health and environmental concerns, necessitating highly sensitive analytical methods for accurate monitoring.

Objectives and Study Overview

This study aims to develop and validate an ultra-sensitive LC-MS/MS method for simultaneous determination of four ethanolamines (diethanolamine, triethanolamine, N-methyldiethanolamine and N-ethyldiethanolamine) in water following ASTM D-7599. The focus is on direct injection of surface water samples with minimal preparation and using isotope-labeled surrogate standards to ensure quantitative accuracy.

Methodology and Instruments

The analytical procedure combines a HILIC separation with triple quadrupole mass spectrometry under single reaction monitoring (SRM). Key steps include:

• Preparation of seven calibration standards in the range 5–1000 ppb using a methanolic stock solution.
• Spike recovery assessment at three levels (50, 100 and 250 ppb) with diethanolamine-D8 as internal surrogate.
• Filtration through 0.45 µm PVDF syringe filters before injection.
• Separation on Shim-Pack Velox HILIC column with gradient elution (acetonitrile, water, 20 mM ammonium acetate).
• Detection by Shimadzu LCMS-8045 with heated ESI probe disabled for improved reproducibility.

Used Instrumentation

• Shimadzu Nexera UPLC system coupled to LCMS-8045 triple quadrupole mass spectrometer
• Shim-Pack Velox HILIC column (2.7 µm, 100 × 2.1 mm)
• Heated ESI probe (heater and gas turned off during analysis)
• Pumps and autosampler configured for gradient elution at 0.4 mL/min
• PVDF 0.45 µm syringe filters for sample cleanup

Main Results and Discussion

The method achieved excellent linearity for all analytes over 5–1000 ppb with correlation coefficients above 0.993. Limits of detection were set at 5 ppb, limited by minor interferences for some compounds. Accuracy ranged between 101 % and 103 % for calibration standards and internal surrogate responses. Spike recoveries in water samples met ASTM criteria, demonstrating robustness of the direct injection approach.

Benefits and Practical Applications

• Direct injection reduces sample handling and potential contamination.
• High sensitivity and selectivity enable trace-level monitoring of ethanolamines in environmental and industrial water.
• Isotope labeled surrogate ensures accurate quantitation and compensates matrix effects.
• Method conforms to ASTM D-7599, facilitating regulatory compliance.

Future Trends and Opportunities

Improvements may include automation of sample preparation, use of alternative stationary phases for faster run times, and application to a broader range of amine-containing contaminants. Integration with high-resolution MS could further enhance specificity and open avenues for non-target screening.

Conclusion

An ultra-sensitive LC-MS/MS method using Shimadzu LCMS-8045 has been established for quantifying four ethanolamines in water at low parts-per-billion levels. The approach provides reliable, high-throughput analysis in line with ASTM D-7599 requirements.

Reference

• ASTM D-7599: Determination of Diethanolamine, Triethanolamine, N-Methyldiethanolamine and Ethyldiethanolamine in Water by Single Reaction Monitoring LC/MS/MS