Carrier Gas Shortages, MS Adoption Major Trends
For all its maturity and secure establishment in chemical analysis, predicting the future of gas chromatography is an exercise in uncertainty.
On the positive side, mass spectrometry detectors were predicted to succeed and that is happening. Today’s most common MS components, single ion traps, are slowly giving way to more capable (and costly) time-of-flight and triple quad detectors. Dr. Ignazio Garaguso, chromatography product specialist at Omnilab- Laborzentrum (Bremen, Germany) notes that newer MS modes allow users in research and discovery labs to probe unknown compounds through fragmentation patterns.
Another trend is the switch from helium carrier gas to hydrogen, yet the zeal with which users are embracing hydrogen is not as clear-cut as for TOF or triple quad MS detectors. The carrier gas switch is based on the worldwide helium shortage, which after four years shows no signs of abating. With major suppliers cutting back on production and issuing “Dear Customer” letters announcing delayed shipments, users are scrambling for solutions.
Hydrogen is far less expensive and more plentiful than helium, and as the carrier gas it serves as fuel for flame ionization detectors. Runs are also significantly shorter due to the atomic mass difference between the two elements. Negatives include flammability (although not at GC usage levels) and the need to rethink methods in several ways.
Garaguso comments that “even when results are similar, the helium-to-hydrogen conversion requires method revalidation.” The other drawback is that where helium is inert, hydrogen is reactive, a characteristic that may complicate MS detection by creation of additional fragments. But Garaguso is reluctant to say that MS detection under hydrogen is inferior. “You get different retention times and different fragments, but I would not say hydrogen is less suitable for MS. It’s different.”
Less certain have been adoption rates of GC and multidimensional GC (GC-GC), which have been growing but not as robustly as experts predicted. Uptake in environmental analysis, for example, has been slow for both GC modalities. The reason is probably related to standardization of common environmental methods and a reluctance on the part of labs to devote resources to redesigning and revalidating newer methods.
No fix for the helium shortage is perfect, as none achieves all desired goals without compromise. Switching to hydrogen or nitrogen carrier gases is fine if methods exist for those mobile phases but inconvenient if they do not.
The simplest solution involves minimizing helium usage. Several firms, including Agilent and Shimadzu, claim substantial gas savings by utilizing less expensive mobile phases for noncritical operations. Thermo Fisher’s approach is based on a new technology being implemented on the split/splitless injector of the company’s TRACE 1300 Series GC, similar to the technology which adopts instant connect detectors and injectors, introduced last year, to facilitate swapping components in and out.
“The idea is to allow users to continue using helium but to conduct all sample splitting and septum purges under much less expensive nitrogen gas,” explains Massimo Santoro, GC marketing manager at Thermo Fisher Scientific (San Jose, CA). “This way, a helium tank will last anywhere from more than three years up to fourteen years, even under heavy use. Even more important, labs run a much lower risk of operational shutdown.”
Unlike with gas-switching strategies, the helium mobile phase chromatography remains unaffected. There is no need to validate new methods or account for lower sensitivity or unanticipated fragmentation in MS detection.
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