Has the Helium Bubble Burst? Using Hydrogen Carrier Gas with Multi-Gas Enabled Thermal Desorption and a Novel EI Source for TD-GC-MS Analysis of Standard Ambient Air Monitoring Methods

Air Monitoring, Methods, and Technology
Oral Presentation

Presented by A. Smith- Henry
Prepared by L. Miles1, A. McQuay2
1 - Markes International, 1000B Central Park, Western Avenue, Bridgend, Wales, CF31 3RT, United Kingdom
2 - Agilent Technologies, 2850 Centerville Road, Wilmington, DE, 19808, United States


Contact Information: [email protected]; +44 1443 230935

ABSTRACT

Helium has long been the gas chromatographer’s carrier gas of choice, it provides faster separations than nitrogen, is considered safer than hydrogen and, until recent years, has been in ready supply. Once again analytical labs find themselves facing a global helium shortage with prices rising and no guaranteed supply of this vital component. It's not surprising then that many laboratory managers are looking for a more sustainable alternative to helium & exploring the option of hydrogen carrier gas. The benefits of hydrogen in gas chromatography (GC) are widely accepted, it can be generated in the lab in a cost-effective manner and produces fast chromatography & higher sample throughput.
However since hydrogen is a reactive gas, hydrogenation and de-chlorination reactions can and do occur in the mass spectrometer electron ionization (EI) source. These reactions can make applying hydrogen carrier gas to standardised ambient air methods using thermal desorption such as US EPA TO-15 & TO-17, and Chinese EPA method HJ 759 difficult due to altered mass spectral ion ratios, spectral infidelity, and peak tailing. The combination of Multi-Gas enabled thermal desorption systems with the development of a new and novel EI source to address these hydrogen-related issues improves performance with hydrogen carrier gas in GC/MS.
In the presentation several examples will be shown demonstrating full method compliance, increased productivity, optimal peak shapes and the absence of any in-source reactions, for a number of environmental standard methods, when using hydrogen carrier gas and modern TD-GC-MS systems.