Hydrogen in GC-FID applications is used to produce the flame that converts the sample into electrically-charged ions that produce the required electrical signals that generate the chromatograph.

The vast majority of GC-FID applications use hydrogen for this purpose but to date the analytical accuracy and limits of detection achieved have been limited by the purity of the hydrogen and air that is commercially available. For optimum analytical results it is important to use the highest grade of gas possible, with a low total hydrocarbon (THC) content.

When the purity of the hydrogen or air used in the GC-FID application falls short of the quality needed for such gas analysis, it results in a phenomenon known to chemists as ‘baseline noise’ – the appearance of unwanted peaks on the chromatogram. These imperfections can make it virtually impossible to measure the area beneath the peaks accurately. For the oil or gas analyst, this means that it may not be possible to detect some components in the sample at all, simply because they are present at very low concentrations below the limit of detection.

In the ongoing drive for improved accuracy, these imperfections are no longer acceptable and the petrochemical and natural gas industries are demanding quality gas products that are capable of producing highly accurate analyses and improved limits of detection, time after time. Ultimately, this focus on accuracy gives the process manager better control over the process and can help to improve overall plant efficiency.

In a bid to improve the accuracy of GC-FID applications, Air Products has developed a new hydrogen product which uses its own BIP technology to deliver an exceptional ultra-high purity gas product, with critical impurities such as oxygen, water and hydrocarbons dramatically reduced compared to conventional hydrogen grades.

Fitted with an internal purifier and patented valve system, the technology effectively ensures that the gas meets the highest standard of purity at the point of use, every time it is used.

This technological development has the potential to make a big difference. For the analyst, using the ultra-high purity BIP hydrogen will significantly lower detection levels and provide an assurance of improved accuracy.

For some oil and gas industry customers, there could be further benefits too if they consider extending their use of pure hydrogen to other analytical applications.

A recent survey by LCGC Europe has revealed that 73percent of the problems that arise in GC analysis are due to impurities in the carrier gas. Such impurities are typically water and oxygen and they need only be present at very low levels to affect the accuracy and reliability of analyses.

In order to eliminate this problem, petrochemical and natural gas industry customers are increasingly using higher purity gases and currently, the carrier gas of choice is helium, which provides fast analysis combined with a high level of analytical accuracy. As a carrier gas, helium compares very favourably to nitrogen, which while lower in cost results in much slower analysis.

However, the arrival of the ultra-high purity BIP hydrogen presents an opportunity for petrochemical and oil industry operators to improve efficiency by further increasing the speed of analysis in some applications.

When hydrogen is used as a carrier gas, it is possible to complete each analysis with a time saving that can be as high as 35percent. There is another benefit too – when using hydrogen as a carrier gas, the analytical results produced can often be even more accurate than when using helium.

Despite the potential improvements with hydrogen, helium is likely to remain the carrier gas of choice for the petrochemical and natural gas industries mainly because it is totally inert and therefore does not react at all with any components in the sample. However, for some laboratories where there is a particularly high level of usage, the efficiencies that could be attained by switching to hydrogen as a carrier gas are difficult to ignore.

In such circumstances, using hydrogen has recently become all the more viable due to the safety features that have been introduced to modern gas chromatographs, such as flow rate monitors that will automatically shutdown the hydrogen supply if a leak is detected.

The introduction of these safety features, combined with the availability of the
ultra-high purity BIP hydrogen gas, is encouraging a growing number of analytical users to consider using hydrogen as a carrier gas for the first time.

he cumulative effect of these recent developments presents an opportunity for the petrochemical and natural gas industries as they look for ways to increase analytical accuracy, improve limits of detection and produce ever more high performance, high-tech fuel and energy solutions for the modern age. While ideal as a fuel gas for most GC-FID applications, even the purest form of hydrogen has its limitations and is unlikely to replace helium as the industry's preferred carrier gas.

However, the new hydrogen alternative is already attracting significant interest internationally and the full potential of the efficiency benefits it is capable of delivering has yet to be fully explored. o

Gary Yates is Air Products’ European Product Manager Analytical and Laboratories, Walton-on-Thames, Surrey, England. www.airproducts.co.uk