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M7 Single Quadrupole GCMS Mass Spectrometry for environmental protection M7 Single Quadrupole GCMS is the new generation high performance Mass Spectrometer designed by Persee, who solely holds intellectual property rights. The basic setup of a FAB ion source is shown in the Figure taken from the JEOL data system. This blog serves for sharing advanced GC-MS techniques, instruments, methods, applications and opinions. Recently the subject of helium shortage and the possible use of hydrogen or nitrogen as alternative carrier gases in GC-MS became a hot topic in various forums, blogs and GC-MS vendor seminars.
In short, we believe that the helium shortage problem is not a long lasting one as alternative natural gas wells are being found and they are likely to contain helium due to long time radioactivity in deep gas wells, albeit the helium price might increase. If and when the helium supply is disrupted, hydrogen or nitrogen can serve as natural alternative carrier gases, but they do come with their own set of problems. Keep reading to find out how the 5975-SMB GC-MS with Cold EI enables helium-free unperturbed operation with nitrogen as its column carrier gas and hydrogen as the Cold EI make up gas.
Clearly Helium is the ideal gas for the operation of standard GC-MS and similarly GC-MS with Cold EI.
Sample: Aviv Analytical standard test mixture of 10 ppm each Hexadecane (n-C16H34), Methylstearate, Cholesterol and n-C32H66 in hexane. As demonstrated in the figure below, GC-MS with Cold EI works effectively with nitrogen as the column carrier gas and hydrogen as the make up gas. Our advice is to stay with helium and purchase an additional spare helium gas cylinder if you suspect that its supply could suffer from short-time shortage periods. Accordingly, the 5975-SMB GC-MS with Cold EI can be effectively operated with nitrogen as column carrier gas and hydrogen as nozzle make up gas, with minimal changes to the analysis method and with little signal loss while having about the same noise level. You are invited to share your GC-MS insights, thougths, recent interesting findings and application notes in a concise way of up to about two pages and a figure or two.
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XBS Triple Filter Mass Spectrometer configured for k-cell and e-gun MBE Deposition Rate Monitoring.
GC-MS 6800 Gas Chromatograph Mass Spectrometer(GC-MS Analysis) Introduction GC-MS 6800 GC-MS Analysis is a cost-effective gas chromatograph mass spectrometer. LCMS-2020 Mass Spectrometer Systems Delivering the ultimate in measurement speed and sensitivity, the compact LCMS-2020 mass spectrometer offers faster measurements and higher detection sensitivity for quicker and more accurate detection of trace impurities, environmental pollutants, and other contaminants.
To stabilize formation of ions, the monitored emission current is always compared to the setting value and the result is feed-backed to the filament current source.


They are usually administered orally but are sometimes injected intramuscularly and intravenously. Its softness results from combining the desorption of the analyte from the condensed phase with its subsequent ionization. Different from EI or CI modes of operation, the ion source is kept close to room temperature to prevent rapid evaporation of the liquid solvent, i.e. It is aimed for those that are passionate about Gas Chromatography Mass Spectrometry and wish to learn about recent advances in GC-MS as well as to share with others their recent achievements and interesting findings.
We published our opinion on this topic in another post called "Helium Shortage and Hydrogen as a Carrier Gas for GC-MS" a few months ago. Due to the advantages of using Helium our advice is to continue and use it as the carrier gas for GC-MS while purchasing additional cylinders "just in case" a temporal shortage will occur. Hydrogen is a reactive gas and it degrades certain compounds without a simple indication to what these compounds could be. Helium is perfectly inert, enables faster GC separation (compared with N2) and provides the best sensitivity due to its minimal ionization cross section hence lowest intra-ion source space charge. The sample was originally purchased from Restek at 1000 ppm and diluted to 10 ppm by Aviv Analytical. GC-MS 6800 GC-MS Analysis holds several patented technologies, and are widely used in industrial inspection, food hygiene, environmental protection, etc. GC-MS applications - Where a GC is needed, especially when an unknown sample needs to be determined. Before the ultimate inactivation of the compound in the liver, 30-40% binds to plasma proteins, and the rest is distributed in various tissues. This is effected by bombarding a liquid solution of the analyte with fast atoms (Ar or Xe of 3-8 keV) or fast ions (Cs+ up to 35 keV). Note that this hydrogen related reactivity is mostly indirect, via the promotion of surface activity at the liner, column and standard EI ion source metallic surfaces.
The right side mass spectra are the Cold EI mass spectra of Cholesterol which is the most delicate sample compound in the mixture used. The use of nitrogen as column carrier gas is not as flexible as helium and it does not permit the use of high column flow rate or flow programming without signal loss. DESCRIPTION Carboxypeptidase B catalyzes hydrolysis of the basic amino acids lysine, arginine and histidine from the C-terminal end of polypeptides.
The latter version is known as liquid secondary ion mass spectrometry (LSIMS or liquidSIMS).


From the drawing you can easily follow the flow of neutral Xe into the FAB gun where Xe ions are generated by EI. Nitrogen is also a little less effective than Helium in gas chromatography at a given temperature programming rate, and in view of its lower column flow rate is less effective in the analysis of labile compounds, BUT, it provides an inert alternative to helium and permits the continued operation of GC-MS with Cold EI under helium shortage conditions.
The advantage of such a combination ion source is in that it circumvents breaking the high vacuum. The ions are accelerated, focussed and neutralized by charge exchange with neutral Xe in the collision cell. GC-MS with Cold EI requires a light carrier gas for both effective jet separation and sample acceleration for the filtration of vacuum background. Dominant molecular ion was observed and no sign for any degradation was found with the use of hydrogen as make up gas.
Thus, when modes are being switched one only needs to wait for heat up or cool down to the respective temperature of operation. The atom beam hits the drop of sample on the target and then, the emerging secondary ions are accelerated and focussed towards the analyzer by use of the ion source optics. However, while hydrogen can be used instead of helium for the analysis of hydrocarbons, its reactivity precludes its use for most other types of analysis and thus, for most analysis, nitrogen must be used as the column carrier gas.
Thus, the best idea that we conceived was to use nitrogen as the column carrier gas and hydrogen as the supersonic nozzle make up gas. Consequently, a nitrogen gas line was connected as usual to the GC instead of helium while a hydrogen gas line was separately connected to the Aviv Analytical make up gas supply that has its own electronic flow controller (Alicat).
From pure gas dynamic consideration we note that 8% N2 in H2 has the same average mass 4.0 of helium. Cold EI ion source tuning with this gas mixture was simple and in comparison with helium it required more negative focus Lens 2 voltage (-30V) and more importantly the nozzle-skimmer distance had to be increased from 7 mm to about 11-12 mm.
We found that hydrogen induced emission current reduction, and at our standard filament operation power (what we normally use with helium) it resulted in x4 lower emission current.
This effect is likely due to hydrogen related increase in the tungsten filament work function (Nitrogen itself did not affect the emission).



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