Simultaneous SIM/Scan P&T‑GC/MSD: High‑Confidence, High‑Sensitivity VOC QuantitationNew Organic Monitoring Techniques
Oral Presentation
Presented by A. Andrianova
Prepared by J. Lehman1, T. Hartlein2
1 - Agilent Technologies, 2850 Centerville Rd, Wilmington, DE, 19808, United States
2 - Teledyne Tekmar Company Inc, 4736 Socialville Foster Rd, MASON, OH, 45040-8265, United States
Contact Information: [email protected]; 302-290-2005
ABSTRACT
Environmental VOC analysis demands sub ppb sensitivity without sacrificing spectral fidelity for confirmation and unknowns review. In this work, we demonstrate a simultaneous SIM/Scan acquisition strategy on purge and trap (P&T) GC/MSD that delivers robust performance across the full EPA 8260 target suite, from early eluting light gases (e.g., vinyl chloride) through late eluting aromatics (e.g., hexachlorobutadiene). The method employs a 30 m DB 624 UI column with optimized method parameters and a Tekmar #9 trap, implemented on an Atomx XYZ–GC/MSD platform with a ≤15 min total cycle time to maintain laboratory throughput. Standards and samples were prepared in 5 mL of deionized water. Methanol compensation was employed for a total of 100ul. This final volume consisted of calibration standards and P&T grade methanol.
SIM was time-segmented for specific analytes to maximize low level response, while full scan data points were acquired concurrently to preserve complete EI spectra for confirmation and retrospective investigation. Recent field and laboratory datasets demonstrate:
• calibration ranges covering 0.2–1000 ppb for vinyl chloride and 10-1000ppb for the gas compounds, while standard VOCs were calibrated from 1-100ppb. Compound-specific low range windows for challenging late eluters (e.g., 1,4-Dichlorobenzene 0.1–100 ppb; Hexachlorobutadiene 0.5–100 ppb);
• sub-ppb MDLs for most targets;
• improved peak shape and chromatographic stability for early eluting light gases associated with the 30 m DB 624 UI column and optimized method parameters.
In production MDL studies, all targets met criteria after exclusion of anomalous runs except 1,2-dibromo-3-chloropropane (DBCP); evaluation of m/z 157 as an alternate quantifier is ongoing and shows promise. Improved peak symmetry and retention stability for light gases and early eluting VOCs supported consistent linear or quadratic calibration models that met site criteria while retaining full mass spectral confirmation.
This work provides a practical, production ready approach for achieving high sensitivity via SIM while preserving full scan spectral context within routine purge and trap laboratory workflows.
