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72-521: The Spacecraft Atmosphere Monitor (SCRAM) is a highly compact gas chromatograph mass spectrometer ( GCMS ) instrument built by JPL that is a technology demonstration on the International Space Station for monitoring the cabin atmosphere in human spacecraft. SCRAM measures both the major constituents (e.g. nitrogen , oxygen , and carbon dioxide ) and trace parts per billion volatile chemicals (e.g. benzene , ethanol , siloxanes )in

144-474: A charcoal column that also used mercury. Gerhard Hesse, while a professor at the University of Marburg /Lahn decided to test the prevailing opinion among German chemists that molecules could not be separated in a moving gas stream. He set up a simple glass column filled with starch and successfully separated bromine and iodine using nitrogen as the carrier gas. He then built a system that flowed an inert gas through

216-413: A constant sensitivity over long period of time. In addition, when alkali ions are not added to the flame, AFD operates like a standard FID. A catalytic combustion detector (CCD) measures combustible hydrocarbons and hydrogen. Discharge ionization detector (DID) uses a high-voltage electric discharge to produce ions. Flame photometric detector (FPD) uses a photomultiplier tube to detect spectral lines of

288-524: A current between the electrodes. The increase in current is translated and appears as a peak in a chromatogram. FIDs have low detection limits (a few picograms per second) but they are unable to generate ions from carbonyl containing carbons. FID compatible carrier gasses include helium, hydrogen, nitrogen, and argon. In FID, sometimes the stream is modified before entering the detector. A methanizer converts carbon monoxide and carbon dioxide into methane so that it can be detected. A different technology

360-438: A detector response. Nitrogen–phosphorus detector (NPD), a form of thermionic detector where nitrogen and phosphorus alter the work function on a specially coated bead and a resulting current is measured. Dry electrolytic conductivity detector (DELCD) uses an air phase and high temperature (v. Coulsen) to measure chlorinated compounds. Mass spectrometer (MS), also called GC-MS ; highly effective and sensitive, even in

432-427: A gas switching valve system; adsorbed samples (e.g., on adsorbent tubes) are introduced using either an external (on-line or off-line) desorption apparatus such as a purge-and-trap system, or are desorbed in the injector (SPME applications). The real chromatographic analysis starts with the introduction of the sample onto the column. The development of capillary gas chromatography resulted in many practical problems with

504-545: A glass condenser packed with silica gel and collected the eluted fractions. Courtenay S.G Phillips of Oxford University investigated separation in a charcoal column using a thermal conductivity detector. He consulted with Claesson and decided to use displacement as his separating principle. After learning about the results of James and Martin, he switched to partition chromatography. Early gas chromatography used packed columns, made of block 1–5 m long, 1–5 mm diameter, and filled with particles. The resolution of packed columns

576-404: A number of problems inherent in the use of syringes for injection. Even the best syringes claim an accuracy of only 3%, and in unskilled hands, errors are much larger. The needle may cut small pieces of rubber from the septum as it injects sample through it. These can block the needle and prevent the syringe filling the next time it is used. It may not be obvious that this has happened. A fraction of

648-440: A radioactive beta particle (electron) source to measure the degree of electron capture. ECD are used for the detection of molecules containing electronegative / withdrawing elements and functional groups like halogens, carbonyl, nitriles, nitro groups, and organometalics. In this type of detector either nitrogen or 5% methane in argon is used as the mobile phase carrier gas. The carrier gas passes between two electrodes placed at

720-406: A short academic paper in 1944 to Naturwissenschaften , which was accepted and she informed them that future experimental work would follow. The paper however was not published at the time, because the journal's printing press was destroyed during air bombardment . It was finally published thirty years later in 1976 at which point it was considered a historical document. In December 1944,

792-507: A small number of samples), to robotic technologies (XYZ robot vs. rotating robot – the most common), or to analysis: The column inlet (or injector) provides the means to introduce a sample into a continuous flow of carrier gas. The inlet is a piece of hardware attached to the column head. Common inlet types are: The choice of carrier gas (mobile phase) is important. Hydrogen has a range of flow rates that are comparable to helium in efficiency. However, helium may be more efficient and provide

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864-423: A small quantity of sample. This detector can be used to identify the analytes in chromatograms by their mass spectrum. Some GC-MS are connected to an NMR spectrometer which acts as a backup detector. This combination is known as GC-MS-NMR . Some GC-MS-NMR are connected to an infrared spectrophotometer which acts as a backup detector. This combination is known as GC-MS-NMR-IR. It must, however, be stressed this

936-445: A substance can be measured, but it is often required that the sample must be measured in comparison to a sample containing the pure, suspected substance known as a reference standard . Various temperature programs can be used to make the readings more meaningful; for example to differentiate between substances that behave similarly during the GC process. Professionals working with GC analyze

1008-510: A temperature controlled oven. As the chemicals exit the end of the column, they are detected and identified electronically. Chromatography dates to 1903 in the work of the Russian scientist, Mikhail Semenovich Tswett , who separated plant pigments via liquid column chromatography. The invention of gas chromatography is generally attributed to Anthony T. James and Archer J.P. Martin . Their gas chromatograph used partition chromatography as

1080-464: Is also frequently determined by the detector, though the level of sensitivity needed can also play a significant role. Typically, purities of 99.995% or higher are used. The most common purity grades required by modern instruments for the majority of sensitivities are 5.0 grades, or 99.999% pure meaning that there is a total of 10 ppm of impurities in the carrier gas that could affect the results. The highest purity grades in common use are 6.0 grades, but

1152-449: Is at 394 nm. With an atomic emission detector (AED), a sample eluting from a column enters a chamber which is energized by microwaves that induce a plasma. The plasma causes the analyte sample to decompose and certain elements generate an atomic emission spectra. The atomic emission spectra is diffracted by a diffraction grating and detected by a series of photomultiplier tubes or photo diodes. Electron capture detector (ECD) uses

1224-595: Is calculated by finding the response of a known amount of analyte and a constant amount of internal standard (a chemical added to the sample at a constant concentration, with a distinct retention time to the analyte). In most modern GC-MS systems, computer software is used to draw and integrate peaks, and match MS spectra to library spectra. In general, substances that vaporize below 300 °C (and therefore are stable up to that temperature) can be measured quantitatively. The samples are also required to be salt -free; they should not contain ions . Very minute amounts of

1296-401: Is contained inside of a separation column. Today, most GC columns are fused silica capillaries with an inner diameter of 100–320 micrometres (0.0039–0.0126 in) and a length of 5–60 metres (16–197 ft). The GC column is located inside an oven where the temperature of the gas can be controlled and the effluent coming off the column is monitored by a suitable detector. A gas chromatograph

1368-413: Is made of a narrow tube, known as the column , through which the vaporized sample passes, carried along by a continuous flow of inert or nonreactive gas. Components of the sample pass through the column at different rates, depending on their chemical and physical properties and the resulting interactions with the column lining or filling, called the stationary phase . The column is typically enclosed within

1440-528: Is the collection of conditions in which the GC operates for a given analysis. Method development is the process of determining what conditions are adequate and/or ideal for the analysis required. Conditions which can be varied to accommodate a required analysis include inlet temperature, detector temperature, column temperature and temperature program, carrier gas and carrier gas flow rates, the column's stationary phase, diameter and length, inlet type and flow rates, sample size and injection technique. Depending on

1512-446: Is the polyarc, by Activated Research Inc, that converts all compounds to methane. Alkali flame detector (AFD) or alkali flame ionization detector (AFID) has high sensitivity to nitrogen and phosphorus, similar to NPD. However, the alkaline metal ions are supplied with the hydrogen gas, rather than a bead above the flame. For this reason AFD does not suffer the "fatigue" of the NPD, but provides

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1584-454: Is the process of separating compounds in a mixture by injecting a gaseous or liquid sample into a mobile phase, typically called the carrier gas, and passing the gas through a stationary phase. The mobile phase is usually an inert gas or an unreactive gas such as helium , argon , nitrogen or hydrogen . The stationary phase can be solid or liquid, although most GC systems today use a polymeric liquid stationary phase. The stationary phase

1656-412: Is two to three times more sensitive to analyte detection than TCD. The TCD relies on the thermal conductivity of matter passing around a thin wire of tungsten-rhenium with a current traveling through it. In this set up helium or nitrogen serve as the carrier gas because of their relatively high thermal conductivity which keep the filament cool and maintain uniform resistivity and electrical efficiency of

1728-504: Is very rare as most analyses needed can be concluded via purely GC-MS. Vacuum ultraviolet (VUV) represents the most recent development in gas chromatography detectors. Most chemical species absorb and have unique gas phase absorption cross sections in the approximately 120–240 nm VUV wavelength range monitored. Where absorption cross sections are known for analytes, the VUV detector is capable of absolute determination (without calibration) of

1800-400: The 1990s, carrier flow rate was controlled indirectly by controlling the carrier inlet pressure, or "column head pressure". The actual flow rate was measured at the outlet of the column or the detector with an electronic flow meter, or a bubble flow meter, and could be an involved, time consuming, and frustrating process. It was not possible to vary the pressure setting during the run, and thus

1872-608: The British Anthony Trafford James and Archer Porter Martin and in 1953, the Czech J. Janak published reports claiming the invention of gas chromatography. Martin and his partner Richard Laurence Millington Synge won the Nobel Prize for partition chromatography, which is often credited for introducing the use of gas as a mobile phase, in 1952. All were completely ignorant of Cremer's early work. This has been attributed to

1944-473: The ISS cabin atmosphere for interesting or anomalous constituents and temporal or spatial variations in the cabin atmosphere. Gas chromatograph Gas chromatography is also sometimes known as vapor-phase chromatography ( VPC ), or gas–liquid partition chromatography ( GLPC ). These alternative names, as well as their respective abbreviations, are frequently used in scientific literature. Gas chromatography

2016-507: The Nazi party came to power in Germany and the institute was dissolved for its reputation as anti-Nazi. Cremer was unable to find work or continue research for four years. Cremer joined Otto Hahn at Kaiser Wilhelm Institute for Chemistry to study radioactive trace compounds in 1937. She moved labs shortly after to concentrate on isotope separation. In 1938, Cremer received her habilitation from

2088-476: The University of Berlin to study chemistry. At the University of Berlin, she attended lectures by Fritz Haber , Walther Nernst , Max Planck , Max von Laue , and Albert Einstein . Cremer received her Ph.D. magna cum laude six years later in 1927 under Max Bodenstein . Her dissertation was on the kinetics of the hydrogen-chlorine reaction. The paper was published under her name only because it concluded that

2160-595: The University of Berlin. In any ordinary case, this qualification would lead to faculty positions; however, the Nazi government of the time had passed the Law on the Legal Position of Female Public Servants. The law banned women from senior positions (e.g. professorship) and required women to quit once married. Many women scientists and scholars were left unemployed or limited in career prospects. After World War II began and male scientists and professors were drafted, Cremer

2232-634: The University of Innsbruck and retired in 1971. She remained active in gas chromatography until almost the end of life. In 1990, an international symposium celebrating her work and her ninetieth birthday was held in Innsbruck. She died in 1996. In 2009, the University of Innsbruck established a program in her name which awards highly qualified women scientist in pursuit of a habilitation degree. Deutsches Museum opened an exhibition on 3 November 1995 which featured Cremer's work in its branch in Bonn , explaining to

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2304-668: The analytical possibilities of the gas chromatograph. Cremer was appointed director of the Physical Chemistry Institute at Innsbruck and was made a professor in 1951. Cremer began presenting Prior and Müller's work in 1947 at various scientific meetings. In 1951, three papers on Cremer's work were published in Zeitschrift für Elektrochemie , a lesser known German scientific journal. The scientific community responded to presentations and papers either negatively or not at all. Many believed that older methods were sufficient. In 1952,

2376-465: The area of the peak using the mathematical function of integration , the concentration of an analyte in the original sample can be determined. Concentration can be calculated using a calibration curve created by finding the response for a series of concentrations of analyte, or by determining the relative response factor of an analyte. The relative response factor is the expected ratio of an analyte to an internal standard (or external standard ) and

2448-415: The best separation if flow rates are optimized. Helium is non-flammable and works with a greater number of detectors and older instruments. Therefore, helium is the most common carrier gas used. However, the price of helium has gone up considerably over recent years, causing an increasing number of chromatographers to switch to hydrogen gas. Historical use, rather than rational consideration, may contribute to

2520-408: The carrier gas. In a flame ionization detector (FID), electrodes are placed adjacent to a flame fueled by hydrogen / air near the exit of the column, and when carbon containing compounds exit the column they are pyrolyzed by the flame. This detector works only for organic / hydrocarbon containing compounds due to the ability of the carbons to form cations and electrons upon pyrolysis which generates

2592-406: The column temperature, the faster the sample moves through the column. However, the faster a sample moves through the column, the less it interacts with the stationary phase, and the less the analytes are separated. In general, the column temperature is selected to compromise between the length of the analysis and the level of separation. A method which holds the column at the same temperature for

2664-399: The column. Generally, chromatographic data is presented as a graph of detector response (y-axis) against retention time (x-axis), which is called a chromatogram. This provides a spectrum of peaks for a sample representing the analytes present in a sample eluting from the column at different times. Retention time can be used to identify analytes if the method conditions are constant. Also,

2736-435: The common methods of the day. She was aware of the liquid absorption chromatography research going on at Innsbruck, so she thought of a parallel method to separate gases which used an inert carrier gas as the mobile phase. She developed mathematical relationships and equations and instrumentation for the first gas chromatograph. Separate components were detected by a thermal conductivity detector. She initially submitted

2808-427: The compounds as they are burned in a flame. Compounds eluting off the column are carried into a hydrogen fueled flame which excites specific elements in the molecules, and the excited elements (P,S, Halogens, Some Metals) emit light of specific characteristic wavelengths. The emitted light is filtered and detected by a photomultiplier tube. In particular, phosphorus emission is around 510–536 nm and sulfur emission

2880-436: The content of a chemical product, for example in assuring the quality of products in the chemical industry; or measuring chemicals in soil, air or water, such as soil gases . GC is very accurate if used properly and can measure picomoles of a substance in a 1 ml liquid sample, or parts-per-billion concentrations in gaseous samples. Erika Cremer Erika Cremer (20 May 1900, Munich – 21 September 1996, Innsbruck )

2952-488: The continued preferential use of helium. Commonly used detectors are the flame ionization detector (FID) and the thermal conductivity detector (TCD). While TCDs are beneficial in that they are non-destructive, its low detection limit for most analytes inhibits widespread use. FIDs are sensitive primarily to hydrocarbons, and are more sensitive to them than TCD. FIDs cannot detect water or carbon dioxide which make them ideal for environmental organic analyte analysis. FID

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3024-411: The detector being used, for example, a DID requires helium as the carrier gas. When analyzing gas samples the carrier is also selected based on the sample's matrix, for example, when analyzing a mixture in argon, an argon carrier is preferred because the argon in the sample does not show up on the chromatogram. Safety and availability can also influence carrier selection. The purity of the carrier gas

3096-421: The detector(s) (see below) installed on the GC, there may be a number of detector conditions that can also be varied. Some GCs also include valves which can change the route of sample and carrier flow. The timing of the opening and closing of these valves can be important to method development. Typical carrier gases include helium , nitrogen , argon , and hydrogen . Which gas to use is usually determined by

3168-425: The end of the column, and adjacent to the cathode (negative electrode) resides a radioactive foil such as 63Ni. The radioactive foil emits a beta particle (electron) which collides with and ionizes the carrier gas to generate more ions resulting in a current. When analyte molecules with electronegative / withdrawing elements or functional groups electrons are captured which results in a decrease in current generating

3240-432: The entire analysis is called "isothermal". Most methods, however, increase the column temperature during the analysis, the initial temperature, rate of temperature increase (the temperature "ramp"), and final temperature are called the temperature program. A temperature program allows analytes that elute early in the analysis to separate adequately, while shortening the time it takes for late-eluting analytes to pass through

3312-447: The fact that Cremer spoke to the wrong people in the wrong places. Austrian analytical and micro chemists did not focus on gases, so the idea did not gain interest. Also, in the post-war years, communication between English and German scientists was poor. Following the new reports, the method of gas chromatography spread widely and Cremer's work slowly gained more recognition. Cremer and her students continued their work on developing both

3384-443: The filament. When analyte molecules elute from the column, mixed with carrier gas, the thermal conductivity decreases while there is an increase in filament temperature and resistivity resulting in fluctuations in voltage ultimately causing a detector response. Detector sensitivity is proportional to filament current while it is inversely proportional to the immediate environmental temperature of that detector as well as flow rate of

3456-532: The first gas chromatograph that consisted of a carrier gas, a column packed with silica gel, and a thermal conductivity detector. They exhibited the chromatograph at ACHEMA in Frankfurt, but nobody was interested in it. N.C. Turner with the Burrell Corporation introduced in 1943 a massive instrument that used a charcoal column and mercury vapors. Stig Claesson of Uppsala University published in 1946 his work on

3528-477: The flow was essentially constant during the analysis. The relation between flow rate and inlet pressure is calculated with Poiseuille's equation for compressible fluids . Many modern GCs, however, electronically measure the flow rate, and electronically control the carrier gas pressure to set the flow rate. Consequently, carrier pressures and flow rates can be adjusted during the run, creating pressure/flow programs similar to temperature programs. The polarity of

3600-506: The hydrogen-chlorine reaction was a chain reaction , which was still considered an extremely original concept for that time. Because of this paper and her work on kinetics, the future Nobel Laureate for the study of kinetics, Nikolay Semyonov invited her to Leningrad to work. She refused and remained in Germany to work at the Kaiser Wilhelm Institute for Physical Chemistry and Electrochemistry with Karl Friedrich Bonhoeffer on

3672-424: The injection technique. The technique of on-column injection, often used with packed columns, is usually not possible with capillary columns. In the injection system in the capillary gas chromatograph the amount injected should not overload the column and the width of the injected plug should be small compared to the spreading due to the chromatographic process. Failure to comply with this latter requirement will reduce

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3744-399: The linear velocity the faster the analysis, but the lower the separation between analytes. Selecting the linear velocity is therefore the same compromise between the level of separation and length of analysis as selecting the column temperature. The linear velocity will be implemented by means of the carrier gas flow rate, with regards to the inner diameter of the column. With GCs made before

3816-499: The methods and theories behind gas chromatography over the next two decades and led to many of contemporary, common use ideas used in gas chromatography. Cremer and her group created the phrase "relative retention time " and how to calculate the peak area through multiplying the peak's height by the width of the peak at half height. Additionally, they demonstrated the relationship between measurement and column temperature and also invented head space analysis. Cremer continued research at

3888-417: The mixture, but functional groups can play a large part in column selection. The polarity of the sample must closely match the polarity of the column stationary phase to increase resolution and separation while reducing run time. The separation and run time also depends on the film thickness (of the stationary phase), the column diameter and the column length. The column(s) in a GC are contained in an oven,

3960-425: The need for detection at very low levels in some forensic and environmental applications has driven the need for carrier gases at 7.0 grade purity and these are now commercially available. Trade names for typical purities include "Zero Grade", "Ultra-High Purity (UHP) Grade", "4.5 Grade" and "5.0 Grade". The carrier gas linear velocity affects the analysis in the same way that temperature does (see above). The higher

4032-690: The number of molecules present in the flow cell in the absence of chemical interferences. Olfactometric detector , also called GC-O, uses a human assessor to analyse the odour activity of compounds. With an odour port or a sniffing port, the quality of the odour, the intensity of the odour and the duration of the odour activity of a compound can be assessed. Other detectors include the Hall electrolytic conductivity detector (ElCD), helium ionization detector (HID), infrared detector (IRD), photo-ionization detector (PID), pulsed discharge ionization detector (PDD), and thermionic ionization detector (TID). The method

4104-492: The only daughter and middle child of Max Cremer and Elsbeth Rosmund. Her father, Max Cremer, was a professor of physiology and the inventor of the glass electrode. She had two brothers, Hubert Cremer, a mathematician, and Lothar Cremer, an acoustician. Cremer's father moved to a new position in Berlin and Cremer had trouble adjusting to the new Prussian school system. Cremer graduated high school in Berlin in 1921 and matriculated to

4176-406: The pattern of peaks will be constant for a sample under constant conditions and can identify complex mixtures of analytes. However, in most modern applications, the GC is connected to a mass spectrometer or similar detector that is capable of identifying the analytes represented by the peaks. The area under a peak is proportional to the amount of analyte present in the chromatogram. By calculating

4248-431: The quantum theoretical problems of photochemistry . Cremer studied the breakdown of alcohols using oxide catalysts on scholarship at the University of Freiburg with George de Hevesy for a brief time. Cremer returned to Berlin to work with Michael Polanyi at Haber's Institut, where they investigated the conversion of hydrogen and ortho-hydrogen in one spin state to para-hydrogen. She remained there until 1933 when

4320-425: The sample is in liquid, gas, adsorbed, or solid form, and on whether a solvent matrix is present that has to be vaporized. Dissolved samples can be introduced directly onto the column via a COC injector, if the conditions are well known; if a solvent matrix has to be vaporized and partially removed, a S/SL injector is used (most common injection technique); gaseous samples (e.g., air cylinders) are usually injected using

4392-410: The sample may get trapped in the rubber, to be released during subsequent injections. This can give rise to ghost peaks in the chromatogram. There may be selective loss of the more volatile components of the sample by evaporation from the tip of the needle. The choice of column depends on the sample and the active measured. The main chemical attribute regarded when choosing a column is the polarity of

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4464-637: The separating principle, rather than adsorption chromatography . The popularity of gas chromatography quickly rose after the development of the flame ionization detector. Martin and another one of their colleagues, Richard Synge , with whom he shared the 1952 Nobel Prize in Chemistry , had noted in an earlier paper that chromatography might also be used to separate gases. Synge pursued other work while Martin continued his work with James. German physical chemist Erika Cremer in 1947 together with Austrian graduate student Fritz Prior developed what could be considered

4536-823: The separation capability of the column. As a general rule, the volume injected, V inj , and the volume of the detector cell, V det , should be about 1/10 of the volume occupied by the portion of sample containing the molecules of interest (analytes) when they exit the column. Some general requirements which a good injection technique should fulfill are that it should be possible to obtain the column's optimum separation efficiency, it should allow accurate and reproducible injections of small amounts of representative samples, it should induce no change in sample composition, it should not exhibit discrimination based on differences in boiling point, polarity, concentration or thermal/catalytic stability, and it should be applicable for trace analysis as well as for undiluted samples. However, there are

4608-448: The solute is crucial for the choice of stationary compound, which in an optimal case would have a similar polarity as the solute. Common stationary phases in open tubular columns are cyanopropylphenyl dimethyl polysiloxane, carbowax polyethyleneglycol, biscyanopropyl cyanopropylphenyl polysiloxane and diphenyl dimethyl polysiloxane. For packed columns more options are available. The choice of inlet type and injection technique depends on if

4680-546: The spacecraft cabin atmosphere to ensure the help safeguard the health of the astronauts. SCRAM has a total mass of 9.5 kg and uses 40W (nominal) during operation. SCRAM is an advanced technology demonstration that can be employed on future crewed flight missions, like in the Artemis program and the Orion spacecraft. It was launched to ISS on a Dragon spacecraft on July 25, 2019, and began continuous operations on July 29, 2019. SCRAM

4752-412: The temperature of which is precisely controlled electronically. (When discussing the "temperature of the column," an analyst is technically referring to the temperature of the column oven. The distinction, however, is not important and will not subsequently be made in this article.) The rate at which a sample passes through the column is directly proportional to the temperature of the column. The higher

4824-445: The university partially reopened, Cremer was still temporarily banned from work due to her German citizenship and would secretly visit the university in a delivery truck to continue research. Cremer was allowed to return to her work in late 1945. Prior completed the research demonstrating a novel method for measurements and qualitative and quantitative analysis in 1947. Another student of Cremer's, Roland Müller wrote his dissertation on

4896-462: The university's facilities were badly damaged in an air bombardment and after the war, Cremer, as a German citizen, was not allowed to use the limited facilities. Fritz Prior was one of her postwar students and a high school chemistry teacher. He chose her idea of the gas chromatograph for his dissertation. Until facilities at the University of Innsbruck were usable again, he used his high school's laboratory to continue Cremer's research with her. When

4968-449: Was a German physical chemist and Professor Emeritus at the University of Innsbruck who is regarded as one of the most important pioneers in gas chromatography , as she second conceived the technique in 1944, after Richard Synge and Archer J.P. Martin in 1941. Cremer was born on 20 May 1900 in Munich, Germany into a family of scientists and university professors . She was

5040-501: Was able to obtain a position as a docent in 1940 at the University of Innsbruck in Austria. However, she was informed that she would leave her job once the war had ended and the men came home. Cremer was pleased with her new position and location because she was able to mountain climb, a hobby of hers. At Innsbruck, Cremer researched the hydrogenation of acetylene and found difficulty separating two gases with similar adsorption heats using

5112-529: Was improved by the invention of capillary column, in which the stationary phase is coated on the inner wall of the capillary. The autosampler provides the means to introduce a sample automatically into the inlets. Manual insertion of the sample is possible but is no longer common. Automatic insertion provides better reproducibility and time-optimization. Different kinds of autosamplers exist. Autosamplers can be classified in relation to sample capacity (auto-injectors vs. autosamplers, where auto-injectors can work

5184-445: Was returned to earth aboard SpaceX-25 on Jan. 24, 2022 after almost two years of continuous operations aboard the ISS, exceeding its design lifetime goal of one year. The instrument was returned to JPL on Feb. 15, 2022. This first SCRAM instrument will be refurbished and be flown, along with a second SCRAM unit (SCRAM-2), to ISS in late 2022. The two instruments operating at the same time will enable JPL scientists to continuously monitor

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