Our general rule is that while using the same column type every factor of two lost GC separation can bring with it a factor of four faster analysis if the right tools for it are available and clearly GC-MS with Cold EI enables very fast GC-MS. Fast GC-MS with Cold EI can be uniquely based on the use of increased injector and column flow rate for achieving fast analysis, combined with a compensation for some loss of chromatographic resolution by the enhanced separation power of the mass spectrometer, either through the enhanced selectivity of the molecular ion EI or with MS-MS.
Please note that the use of increased flow rate results in speeding up all the elements of chromatography including sample injection, chromatography and cooling back due to higher initial oven temperature. Furthermore, the enhanced separation power of the mass spectrometer as well as the high injector and column flow rate enables the fast analysis of thermally labile and relatively non-volatile compounds which otherwise are not amenable for analysis by standard GC-MS. A conventional GC such as the Agilent or Varian is connected to the supersonic nozzle through a short transfer-line simultaneously with two columns, having no limitations on the column ID, length or flow rate.
Even a very short 50 cm long megabore capillary column was connected to the supersonic nozzle, and served for obtaining ultra-fast GC-MS analyses [4,8]. Alternatively, we developed a unique low thermal mass fast GC inlet that enables below one minute analysis cycle time including splitless injection, temperature program and cooling back time.
This fast injection can be performed at relatively higher GC oven temperatures due to the elimination of the need for cryo focusing thus facilitating faster analysis and shorter cooling down time.
A unique extract free dirty sample introduction method and device ChromatoProbe enables a true fast analysis including the step of sample preparation. A novel Open Probe further simplifies and speed-up sample collection and introduction . Effective backflush can be easily achieved.
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A wide temperature range fast GC-MS is achieved without any ion source related peak tailing. Compatible mass scanning rate is enabled with standard quadrupole mass analyzers. Thus, standard quadrupole mass analyzer can be used. Sufficient overall GC-MS resolving power is provided, even for complex mixture fast analysis. The ultra fast cold EI ion source response time allows the monitoring of fast GC peaks originating even from relatively non-volatile molecules without tailing. Superior low concentration sensitivity is achieved with more than one microLiter fast splitless injections due to the high column flow rate.
This is in marked contrast to microbore column fast GC-MS. Fast splitless injections also enable faster temperature programming and GC cooling back time. Simplified sample preparation is achieved due to the superior low concentration sensitivity which allows the injection of smaller amounts of untreated samples. Alternatively, our unique ChromatoProbe and Open Probe devices considerably simplifies sample preparation.
Resolution, time and sensitivity trade-off choice is enabled for optimal results. The coupling with a standard GC is allowed without any constraints on the column diameter, length and carrier gas flow rate.
Thus, critical parameters such as chromatographic time and resolution can be optimized, with regards to and in consideration of the desired injected sample amount. This is easily achieved due to the practically unlimited column flow allowable. Alternatively a unique low thermal mass fast GC can be used for sub one minute full analysis cycle time. Megabore 0. While fast GC-MS is ideally suited for the fast screening of a large number of samples, confirmation is also needed, preferably with the same GC-MS instrument. In conclusion. Supersonic GC-MS enables faster analysis for a broad range of applications and with it the analysis is practicaly always faster.
Probe Sampling for Mass Spectrometry Studies. The ChromatoProbe device, effectively transforms a conventional temperature programmable GC injector, preferably a second GC injector in the GC-MS followed by a short capillary transfer line column 1 m microbore , into a cost-effective alternative to the standard direct insertion probe.
Furthermore, all this is achieved with a low cost. This new method is based on sampling in a test tube micro vial that retains the harmful and non-volatile matrix residue of real world samples. Thus, it eliminates the need for further sample clean-up, while the micro vial is a disposable item. The sample semi-volatile compounds are focused on the early portion of the column and are analyzed by the chromatography as usual. This method brings the many known advantages of thermal extraction in an easy to use low cost fashion, combined with the many advantages of GC-MS with Cold EI and best GC integrity.
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It facilitates extract free analysis of drugs in urine or hair, or pesticides in blended fruit and vegetable items, or in milk, juice and other sludge's. The ChromatoProbe also uniquely allows large volume sample injections of conventional extracts without the associated residues that usually restrict the sample size, and thus lower detected concentration limits can be achieved.
The containment of the non-volatile compounds in the disposable test tube also results in faster analysis that can end at a lower column temperature. The short 15 mm column is inserted into the SnifProbe easy-insertion-port and the SnifProbe is located or aimed at the sample environment. After a few seconds of pumping, the short column is removed from the SnifProbe with a tweezers and placed inside a ChromatoProbe glass vial having a 0. The ChromatoProbe sample holder with its glass vial and sample in the short column are introduced into the GC injector as usual.
The sample is then quickly and efficiently vaporized from the short sample column and is transferred to the analytical column for conventional GC and or GC-MS analysis. Thus, SnifProbe extends the ChromatoProbe range of samples that also includes gas phase samples. SnifProbe is ideal for field or process operation, it is small, enables fast sampling, compatible with the full range of semi volatile compounds and enables low cost sensitive analysis.
GC-MS with Cold EI excels in a wide range of applications due to its exceptionally broad range of advantages and unique features as above. While it can do all the current standard GC-MS analysis it particularly excels with many applications and can uniquely perform a few types of analyses that cannot be done by any other GC-MS. Accordingly, in the majority of both standard and non-standard applications it can replace the available instrumentation and provide a competitive advantage.
A list of a few such major applications includes:. Petroleum and hydrocarbon-MS. Petrochemical analysis benefits from many of the unique features of GC-MS with Cold EI including molecular ion information in alkanes, molecular ion only MS at low electron energies EI, unique isomer information and low boilers large petrochemical compounds GC-MS analysis.
A unique isomer abundance analysis method was developed that enables fuel characterization. Hydrocarbon MS is more than just petroleum analysis and includes arson investigations, fuel characterization, fuel adulteration, geochemical applications, environmental analysis and transformer oil analysis. The features of: a provision of trustworthy enhanced molecular ion; b extended range of thermally labile and low volatility compounds; c elemental formula information via isotope abundance analysis; d uniform compound independent response; e fast analysis; f enhanced isomer and structural MS information; g flexible, fast and easy method development; h easy and fast cold EI-Cluster CI-ChromatoProbe switching, are all important to this application.
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References 23 and 42 describe our success in these types of applications. Recently we demonstrated the unique ability of GC-MS with Cold EI in the optimization of organic chemical reaction yields via semi online monitoring of their progress and products. Pesticide Analysis.
The enhanced molecular ion and reduced matrix interference at the high molecular ion mass spectral range lowers the pesticide identification limits in complex agricultural matrices. The capability of fast GC-MS analysis and extended range of thermally labile pesticides such as carbamates are highly important for this application which was studied in details in reference . The ChromatoProbe device enables extract free pesticide analysis in fruit, vegetables, spices and other food items. Our goal is to have a fast under 8 min analysis cycle time pesticide analysis of broad range of pesticides in a one MS system.
Clinical Toxicology - Screening of Drugs in Urine and bio-fluids. The sensitivity and selectivity of Cold EI combined with fast GC-MS of thermally labile drugs enables few minutes drug screening from the sample to the results. Environmental Analysis In addition to benefits in pesticide analysis, large phthalates analysis benefits from significantly enhanced molecular and high mass fragments.
The analysis of large PAHs with over seven rings is uniquely enabled without any ion source tailing and the analysis of oil and fuel spills is significantly improved through the availability of molecular ions and isomer information. Forensic Analysis The best information generating GC-MS can certainly become an asset in the diversified and demanding field of forensic analysis.
Fast thermally labile explosive analysis is of considerable importance for this application and fast drug screening is also very desirable. Molecular ion and isomer abundance information for arson investigations, trace level drug detection and the use of the ChromatoProbe for dirty powder sample analysis are also of importance while IAA in combination with enhanced molecular ion can be a true asset in general unknown sample identification.
Food and Fragrance Industry The feature of ultimate information content enhanced molecular ion, isomer and structural and isotope abundance analysis are of central importance to these industries.
The extension of the range of compounds amenable for analysis and shorter analysis time are also beneficial. In conclusion, the combination of ultimate confidence level in sample identification, extended range of compounds amenable for analysis, superior sensitivity and faster analysis can benefit the majority of current of future potential GC-MS applications.
An important additional aspect of fast GC-MS pertains to the issue of high repetition rate automated sample injection method. Today, automated sample injection is performed with an autosampler that is capable of performing about one injection per minute. It is also limited to relatively clean samples, in the form of liquid solutions or gases introduced in crimped vials that are located on a sample tray. As a result, the standard autosampler is practically incompatible with the majority of ultra-fast GC-MS analyses, and a new and much faster injection method is desirable for very-fast and ultra-fast GC-MS.
The use of focused or slightly defocused laser light for sample desorption and volatilization seems to be the ideal injection method for ultra-fast GC-MS, comprising several inherent desirable features  including:. High repetition rate automated injection is enabled. With laser desorption injection, the chromatography is the limiting time step since 20 Hz laser operation is standard. Sample preparation is eliminated through the ability to reproducibly desorb and inject a very small sample amount that does not require further clean up.
For this purpose, ultra-fast analysis is clearly essential, otherwise the total mapping time could be prohibitively long. Laser desorption injection is especially suitable for the organic analysis of surfaces, while it can also be used for drilling into the bulk of solids in order to achieve an additional dimension of information. The subject of laser desorption for analytical purposes is not new, and matrix assisted laser desorption ionization is a major subject of research today and is in common use. However, most of the laser desorption schemes are based on laser desorption of samples that are placed inside the mass spectrometer vacuum chamber.
The laser desorption unit was mounted on the existing home made ultra-fast GC-MS injector inlet, with a thermally insulated clamp and mounting rod. The sample was placed on the sample holder, located inside the sample compartment. The laser used was a pulsed XeCl Excimer laser with mJ nm laser pulses of about 12 nsec duration. The laser pulse energy at the sample was only mJ due to its energy reduction through the light transfer optics. The laser pulses were controlled by a pulser and either a single laser pulse or a train of typically 20 pulses at a repetition rate of 50 Hz was employed for 0.