Analysis of Haloacetic Acids and Dalapon in Water by GC-MS Using TraceGOLDTM TG-5MS with SafeGuard GC Column

Importance of the topic

The analysis of haloacetic acids (HAA) and the herbicide dalapon in drinking water is critical for ensuring public health and regulatory compliance. These halogenated acids are regulated contaminants under US EPA method 552.2 due to their potential toxicological effects. Reliable, sensitive, and robust analytical methods are required for routine monitoring and confirmation of trace level HAAs and dalapon in environmental water samples.

Objectives and study overview

This application note evaluates the performance of a TraceGOLD™ TG-5SilMS gas chromatography column with integrated SafeGuard guard for the identification and quantification of ten HAAs and dalapon at 250 ng/mL in water. Using GC–MS in selected ion monitoring (SIM) mode (m/z 59), the study aims to demonstrate compliance with EPA method 552.2 and to compare chromatographic performance versus traditional detectors.

Methodology and instrumentation used

Sample preparation and derivatization

• 20 mL water spiked with 10 µg/mL HAA mix and 250 ng/mL dalapon.
• Acidification to pH < 0.5 with H₂SO₄ and addition of 8 g Na₂SO₄.
• Liquid–liquid extraction with 2 mL methyl tert-butyl ether (MTBE).
• Derivatization in methanolic 10% H₂SO₄ at 50 °C for 2.5 h.
• Quench with saturated NaHCO₃ and final transfer of 500 µL extract to analysis vial.

Chromatographic and mass spectrometric conditions

• GC: Thermo Scientific TRACE GC Ultra
• Column: TraceGOLD TG-5SilMS, 30 m × 0.25 mm × 0.25 µm with 10 m SafeGuard guard.
• Carrier gas: He at 1.2 mL/min constant flow, split ratio 10:1.
• Oven program: 40 °C (1 min), ramp 5 °C/min to 135 °C (1 min).
• Injector: split mode, 220 °C, 2 µL injection.
• MS: Thermo Scientific ISQ single quadrupole, EI 70 eV, source 230 °C, transfer line 260 °C.
• SIM on m/z 59, solvent delay 3.2 min.

Main results and discussion

The TG-5SilMS column with integrated SafeGuard achieved baseline resolution for all ten HAAs and dalapon within 18 minutes. Sharp peak shapes and minimal tailing were observed due to the phenyl-modified stationary phase and guard refocusing. Relative standard deviations of peak area across three replicates ranged from 9% to 18%, indicating acceptable reproducibility without internal standards. The method provided clear identification in SIM at 250 ng/mL, meeting EPA sensitivity requirements.

Benefits and practical applications

• Enhanced column lifetime and protection against derivatization byproducts thanks to the SafeGuard guard.
• Compatibility with mass spectrometric detection enabling confirmatory analysis under EPA method 552.2.
• Improved inertness towards strong acid derivatives, reducing peak tailing.
• Streamlined workflow combining extraction, derivatization, and GC–MS analysis for routine water testing laboratories.

Future trends and opportunities

Advancements may include automated on-line sample preparation to increase throughput, coupling with high-resolution mass spectrometry for lower detection limits and broader analyte coverage, and development of multi-residue methods incorporating HAAs alongside other regulated disinfection byproducts. Green chemistry approaches may reduce solvent usage and derivatization reagents.

Conclusion

The TraceGOLD TG-5SilMS GC column with SafeGuard guard offers a robust solution for the GC–MS analysis of haloacetic acids and dalapon in drinking water. It delivers reliable separation, low bleed, and extended column life under harsh derivatization conditions, fully supporting EPA method 552.2 requirements for confirmatory monitoring.

Reference

1. EPA Method 552.2, Determination of Haloacetic Acids and Dalapon in Drinking Water by Liquid–Liquid Extraction, Derivatization and Gas Chromatography with Electron Capture Detection.