Pesticides and Brominated Flame Retardants by EPA Method 527 on Rxi®-5Sil MS

Importance of the topic

Environmental monitoring of trace-level pesticides and brominated flame retardants is critical for assessing human and ecological exposure. Combining EPA Method 527 with advanced gas chromatography–time-of-flight mass spectrometry (GC×GC-TOFMS) enhances sensitivity, selectivity and throughput, enabling laboratories to meet stringent regulatory requirements and support quality assurance in water, soil and biota analyses.

Objectives and Study Overview

This application study illustrates the simultaneous separation and detection of 17 target analytes—including 10 pesticides and 7 PBDE congeners—using EPA Method 527 on an Rxi®-5Sil MS column. The goals were to demonstrate chromatographic resolution, adequate signal response at 1 ng on-column, and compatibility with routine environmental testing.

Methodology

• Sample preparation: Pesticide and PBDE standard mixes spiked with internal and surrogate standards.
• Diluent: Ethyl acetate:methylene chloride (1:1 v/v).
• Injection: 12.5 µL splitless (hold 0.583 min) at 250 °C using a gooseneck splitless liner packed with semivolatiles wool.
• Oven program: 40 °C hold for 0.60 min, ramp at 30 °C/min to 320 °C, hold 1.07 min.
• Carrier gas: Helium, constant flow 2 mL/min (pressure-ramped control).
• Detection: TOF MS (LECO Pegasus 4D GC×GC-TOFMS) with 45–750 amu range, 10 spectra/sec, solvent delay 3.33 min.

Used Instrumentation

• GC column: Rxi®-5Sil MS, 15 m × 0.25 mm ID × 0.25 µm with IP-deactivated 5 m guard column.
• Connectors: Universal Press-Tight® fittings.
• Mass spectrometer: Time-of-flight analyzer with transfer line at 290 °C, ion source at 225 °C, electron energy ‑70 eV, mass defect offset ‑20 mu/100 u.

Main Results and Discussion

Chromatographic separation achieved baseline resolution for all 17 analytes within a single run of approximately 10 minutes. Key observations include:

• Early elution of polar pesticides (e.g., atrazine, malathion) followed by organophosphates and pyrethroids.
• Later elution of high-mass PBDE congeners (BDE-47, ‑99, ‑100, ‑153, Mirex, Kepone).
• Consistent retention time reproducibility and high signal-to-noise at 1 ng on-column.
• TOF MS provided accurate mass information for unambiguous analyte identification.

Benefits and Practical Applications

• Rapid multi-class analysis reduces instrument time and labor.
• High sensitivity supports trace-level quantitation in compliance with EPA regulatory limits.
• Robust inert flow path and optimized column chemistry minimize analyte adsorption and carryover.
• Applicability across environmental matrices including drinking water, wastewater, soil and biological tissues.

Future Trends and Applications

• Expansion to broader classes of emerging contaminants such as novel flame retardants and transformation products.
• Integration with two-dimensional GC (GC×GC) for enhanced peak capacity in highly complex samples.
• Automation of sample preparation workflows (e.g., online SPE-GC) to increase throughput.
• Use of high-resolution accurate-mass detection for suspect and non-target screening.

Conclusion

The demonstrated method combining EPA Method 527 with Rxi®-5Sil MS GC×GC-TOFMS offers a fast, reliable and sensitive approach for simultaneous quantitation of pesticides and PBDEs. Its robustness and high throughput capacity make it well suited for routine environmental monitoring, regulatory compliance and research applications.

Reference

Restek Corporation Application Note: Pesticides and Brominated Flame Retardants by EPA Method 527 on Rxi®-5Sil MS (LECO Pegasus 4D GC×GC-TOFMS).