Drinking Water Semivolatiles Analysis using the 6890N/5975B inert GC/MSD

Significance of the Topic

The reliable detection and quantification of semivolatiles in drinking water are essential for public health and regulatory compliance. Low detection limits, robust calibration, and minimal analyte activity ensure that trace-level contaminants such as pesticides, acids, bases and neutral organics are accurately monitored. Advances in GC/MS instrumentation that improve sensitivity, linearity and inertness directly translate into more reliable water quality assessment and streamlined laboratory workflows.

Study Objectives and Overview

• Evaluate the performance of the Agilent 6890N/5975B inert GC/MSD for semivolatiles analysis under USEPA Method 525.2 conditions.
• Demonstrate improvements in sensitivity and linearity achieved through inert columns, a high-temperature inert source, and manual tuning procedures.
• Discuss alternative protocols for laboratories not bound by EPA mandates to enhance productivity and lower detection limits.

Methodology and Instrumentation

The system was configured with pulsed splitless injection (1 µL) into an Agilent direct-connect dual-taper inlet liner (no glass wool) at 250 °C. The HP-5MSi column (30 m × 0.25 mm × 0.25 µm) was run at constant helium flow (1.5 mL/min) with a 6890N oven ramp from 40 °C to 320 °C in 24 min. The 5975B inert MSD employed a 6 mm large-aperture drawout lens and source temperature of 300 °C to reduce peak tailing. Retention time locking to phenanthrene-d10 at 11.40 min ensured reproducible retention and simplified database use. Data were acquired in both full-scan (45–450 amu) and AutoSIM modes (26 groups, 115 compounds) at 3.54 scans/s.

Key Results and Discussion

• Full-scan calibration over seven levels (0.1–10 ppm) yielded an average RRF RSD of 8% for 108 analytes; individual standards and surrogates showed RSDs below 6%.
• Sensitivity loss from DFTPP tuning was limited to under 2× through manual lens optimization versus 3–6× under standard DFTPP.
• Semi-quantitative SIM acquisition extended calibration down to 0.01 ppm, reducing detection limits by up to 100× with RSDs of 6–11% across analytes and internal standards.
• Retention time locking maintained integration and SIM window consistency after column trimming or replacement.

Benefits and Practical Applications

The 6890N/5975B inert GC/MSD system meets or exceeds USEPA 525.2 criteria in a 24 min run, providing excellent sensitivity and linearity for over 100 semivolatiles. Manual tuning and inert hardware minimize analyte activity and improve repeatability. Laboratories can boost throughput using liquid–liquid extraction, programmable temperature vaporizing (PTV) large-volume injection, and combined SIM/scan methods without sacrificing confirmatory spectra.

Future Trends and Possibilities

• Broader adoption of PTV and LVI strategies for sub-ppt detection.
• Enhanced auto-tuning algorithms further reducing active compound degradation and manual optimization.
• Integrated SIM/scan workflows for simultaneous quantitation and spectral confirmation in a single run.
• Use of high-resolution mass spectrometry and advanced data processing to lower detection limits and simplify method development.

Conclusion

The Agilent 6890N/5975B inert GC/MSD provides a high-performance platform for semivolatiles analysis in drinking water. Optimized hardware, tuning strategies and acquisition modes deliver robust sensitivity, extended linearity and reproducible retention times, enabling laboratories to meet regulatory requirements and improve productivity.

References

1. USEPA Method 525.2, U.S. Environmental Protection Agency.
2. M. Szelewski, B. Wilson, P. Perkins, Improvements in the Agilent 6890/5973 GC/MSD System for USEPA Method 8270, Agilent Technologies, publication 5988-3072EN.
3. K. Weiner, N. Mata, P. Wylie, Retention Time Locking with the G1701BA MSD Productivity ChemStation, Agilent Technologies, publication 5968-3433E.
4. M. Szelewski, Fast USEPA 8270 Semivolatiles Analysis Using the 6890/5973 Inert GC/MSD, Agilent Technologies, publication 5989-1510EN.
5. H. Prest, D. Peterson, New Approaches to GC/MS Selected Ion Monitoring Acquisition and Quantitation Methods, Agilent Technologies, publication 5988-4188.
6. M. Szelewski, Synchronous SIM/Scan Low-Level PAH Analysis Using the Agilent 6890/5975 Inert GC/MSD, Agilent Technologies, publication 5989-4184EN.
7. C.K. Meng, Identification and Quantitation of Pesticides in the Parts-per-Trillion Range Using Retention Time Locking and GC/MS, Agilent Technologies, publication 5988-4392EN.