Articles and Applications
Background Researchers from Prof. Guido Verbeck’s group at the University of North Texas (UNT) carried out analysis of drugs of abuse (DOA) and explosives using an ion trap GC-MS to compare results when using helium and hydrogen carrier and buffer gas. As well as comparing the two gases, the group also assessed a number of ion volumes with different orifice diameters to look at their effect on sensitivity with either gas.
Talk of a helium crisis following the shortage of 2012/13 appears to have subsided thanks to increased worldwide production, with labs now readily able to obtain helium. Here we look at what has happened over the last 2 years since the global helium shortage was the hot topic in GC, where do we currently stand and what is the outlook in the short term?
Alcohol consumption can seriously affect the ability of a driver to operate a vehicle and blood alcohol content (BAC) directly correlates with this impairment. A number of nations have zero alcohol tolerance for motorists, but the majority of countries worldwide have a limit of between 50 and 80 mg alcohol per 100 ml blood, or 0.05-0.08%. Results are used in court to provide quantitive levels of BAC, which makes it one of the most commonly practised analyses in forensic laboratories. The large number of samples and requirement for speed of sample processing mean that analysis needs to be conducted quickly, whilst giving reliable and accurate results.
Summary Labs worldwide have recently found that helium has been in short supply, leaving a number of labs without carrier gas. Added to this, helium prices have doubled over the past 10 years causing a number of labs to look into alternative carrier gases for GC, such as nitrogen and hydrogen. As well as lower price and unlimited availability, hydrogen has a number of potential advantages over helium, including potential for faster throughput, improved chromatography and better sample resolution.
Changing carrier gas from helium to hydrogen does not always present an opportunity for faster sample analysis. Method revalidation can be simplified by keeping the new method as close to the old method as possible, which will limit changes to sample selectivity and resolution whilst maintaining the retention times of analytes.