Developing an eMethod for the Analysis of Volatile Organic Compounds in Water Using Purge and Trap/GC with Agilent’s New 5975 inert Mass Spectrometer

Significance of the Topic

Ensuring accurate quantitation of volatile organic compounds in water is vital for environmental monitoring regulatory compliance and protection of public health. Traditional GC/MS methods require manual entry of instrument parameters and frequent retention time adjustments which can introduce variability between laboratories. Agilent eMethods combined with retention time locking and inert mass spectrometry flow paths address these challenges by enabling rapid portable method transfer and robust VOC analysis.

Study Objectives and Overview

This work aims to develop and validate an electronic method for analysis of 60 EPA Target VOCs in water using purge and trap GC/MS compliant with USEPA Method 8260B. Key objectives include packaging complete GC and MS parameters into a transferable eMethod demonstrating retention time locking calibration performance and implementing synchronous SIM/scan acquisition to enhance sensitivity without sacrificing scan data.

Methodology and Experimental Design

Water calibration standards were prepared at seven levels from 1 to 200 µg/L in 100 mL volumetric flasks spiked with a 2000 µg/mL VOC mix internal standards and surrogates. Purge and trap of 5 mL water samples employed a Tekmar Velocity XPT concentrator with a 3000 trap under specified purge purge rinse and bake conditions. GC separation used a 20 m × 0.18 mm × 1.0 µm DB-VRX column at constant helium flow with RTL of toluene-d8. The Agilent 6890N GC coupled to a 5975 inert MSD acquired data in scan and synchronous SIM/scan modes.

Used Instrumentation

• Tekmar Velocity XPT purge and trap with TekLink 2.4 control
• Agilent 6890N gas chromatograph Split Splitless inlet
• 20 m × 0.18 mm × 1.0 µm DB-VRX capillary column
• Agilent 5975 inert mass selective detector MSD Productivity ChemStation with eMethod import export

Main Results and Discussion

Calibration curves from 1 to 200 µg/L showed average response factor RSD of 4.3% for 59 analytes easily meeting the EPA 8260B requirement of 15%. System performance check compounds and continuing calibration compounds all passed specified limits. Initial nonlinearity and high RSDs observed for certain low-boiling analytes were resolved by replacing inlet liners and column to eliminate active site reactions. Synchronous SIM/scan acquisition improved sensitivity tenfold for target ions without loss of scan data achieving S/N ratios of 749 in SIM mode and comparable scan sensitivity to scan-only runs.

Benefits and Practical Applications

eMethods dramatically reduce method setup time and risk of parameter errors when sharing GC/MS methods across multiple instruments or laboratories. Retention time locking ensures consistent analyte identification while inert MSD flow paths minimize adsorption artifacts for trace VOCs. The validated procedure supports routine environmental monitoring drinking water analysis and QA/QC of industrial effluents in alignment with USEPA Method 8260B.

Future Trends and Potential Applications

Expansion of eMethods to additional sample matrices and analyte classes such as semivolatiles and pesticides promises to further standardize interlab workflows. Integration with cloud-based repositories and real-time instrument monitoring will facilitate global method distribution and performance tracking. Advances in trap materials and MS detector technologies can extend sensitivity to ultra-trace levels and emerging contaminants.

Conclusion

The developed eMethod for purge and trap GC/MS of 60 VOCs in water demonstrates streamlined electronic method transfer robust calibration linearity and enhanced sensitivity via synchronous SIM/scan acquisition. Retention time locking and an inert mass spectrometer flow path ensure reproducibility and data quality across laboratories, significantly improving VOC analysis workflows.

References

1. USEPA SW-846 Method 8260B volatile organic compounds by gas chromatography mass spectrometry revision 2 December 1996
2. USEPA Method 524.2 methods for the determination of organic compounds in drinking water Supplement III revision 4.1 1995
3. Philip L Wylie BFB tuning for environmental analysis three ways to succeed Agilent publication 5988-4373EN
4. Philip L Wylie techniques for optimizing the analysis of volatile organic compounds in water using purge and trap GC MS Agilent publication 5989-0603EN
5. USEPA Method 502.2 volatile organic compounds in water by purge and trap capillary column gas chromatography with photoionization and electrolytic conductivity detectors in series revision 2.1 1995