Improved Performance with Hydrogen Carrier Gas Methods for SVOC and Organochlorine Pesticides Analysis by GC/MS/MSNew Organic Monitoring Techniques
Oral Presentation
Prepared by J. Mitchell1, B. Mock2, E. Fausett3, A. Andrianova4, B. Quimby4
1 - Pace Analytical Services, 12065 LEBANON ROAD, Mt. Juliet, TN, 37122, United States
2 - PACE ANALYTICAL, 12065 LEBANON ROAD, Mt. Juliet, TN, 37122, United States
3 - Agilent, 2850 Centerville Road, Wilmington, DE, 19808, United States
4 - Agilent, 2850 Centerville Road, Wilmington, DE, 19808, United States
Contact Information: [email protected]; 615-944-9517
ABSTRACT
GC Single Quadrupole MS (GC/SQ) has long been a standard for analyzing semi-volatile organic compounds (SVOCs) in environmental samples, but GC/TQ is emerging as a more powerful alternative due to its enhanced sensitivity and selectivity. Using Multiple Reaction Monitoring (MRM) in GC/TQ, sensitivity is increased, allowing for smaller sample extraction volumes and reducing costs for solvents, sample preparation, and waste disposal. MRM also reduces matrix interferences, enabling the analysis of more compounds, faster batch reviews, and greater confidence compared to GC/SQ in SIM or Scan modes. Additionally, with helium shortages, hydrogen has become a viable carrier gas alternative, offering benefits such as reduced GC/MS source cleaning, minimized peak tailing, and improved internal standard stability. This study discusses the successful adaptation of hydrogen as the carrier gas in GC/TQ for SVOC analysis.
The GC/TQ method was adapted from a successful helium-based method by translating it to hydrogen using method translation tools. Optimized conditions included reducing column dimensions from 30m x 0.25mm to 20m x 0.18mm while maintaining the same phase ratio for consistent retention times and elution order. Inlet conditions were optimized, including the use of a mid-frit liner and adjusting pulsed injection parameters. Temperature settings were 280°C for the GC inlet, 320°C for the GC-MS transfer line, and 300°C for the MS source.
Using hydrogen as the carrier gas, the system achieved comparable or superior results to helium. The analysis of 179 MRMs for over 80 target compounds showed excellent calibration and stability. For SVOC calibration (0.1-10 µg/mL), 57 out of 61 compounds fit average RF RSD calibrations, with R^2 values >0.995 for the four quadratically fitted compounds. Carryover was below 0.03%, and internal standard stability was within +/- 28% across the calibration curve.
