what is a major requirement for an analyte in order for it to be separated by gc?

Gas Chromatography

Gas chromatography (GC) coupled with a flame ionization detector (FID) in combination with a methanizer and GC coupled with a mercuric oxide reduction detector (GC-HgO) are the two most widely used techniques for CO measurements in air samples (Zellweger et al., 2019).

From: Asian Atmospheric Pollution , 2022

Physicochemical fuel backdrop and tribological behavior of aegle marmelos correa biodiesel

Vinoth Thangarasu , R. Anand , in Advances in Eco-Fuels for a Sustainable Environment, 2019

11.3.2 The fatty acid limerick of AMC biodiesel

Gas chromatography (GC) is the nigh unremarkably adopted technique as the standard method to determine FAME content in biodiesel by regulatory and monitoring agencies in the majority of countries. The composition pct of fatty acids in Aegle Marmelos Correa Biodiesel was determined using the analytic method GC-MS that combines features of gas chromatography and mass spectrometry. GC-MS results show that Aegle Marmelos Correa Biodiesel contains saturated fatty acids such as behenic acid, arachidic acid, palmitic acid, lignoceric acrid, and stearic acid, and unsaturated fatty acids such every bit linolenic acid, oleic acid, and linoleic acid. AMC biodiesel contains 32.29% saturated fatty acids and the remaining are unsaturated fatty acids. Linoleic acrid, oleic acid, and palmitic acid were nowadays in a big percentage, approximately 25% each in AMC biodiesel. The percentage of each fat acids shown in Fig. xi.3.

Fig. eleven.3. Fat acid composition of AMC biodiesel.

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Methods for the detection and limerick study of fluid inclusions

Shuming Wen , ... Jiushuai Deng , in Fluid Inclusion Effect in Flotation of Sulfide Minerals, 2021

three.4.2.2.3 Gas chromatography

GC is a cavalcade chromatography technique using an inert gas (N₂, He, Ar, H₂, etc.) every bit the mobile stage. The mixed gas is separated based on differences in physical and chemical properties, such as the boiling betoken, polarity, and adsorption of the substance. Fig. 3.11 shows a chromatographic arrangement including the pure carrier gas source, sampling inlet (vaporizer for liquid sample), chromatographic column, and detector (for separation over time). Equally the components pass, the betoken output value of the detector changes to answer to the components.

Figure 3.eleven. Bones menstruum blueprint of gas chromatography.

In geology, vacuum explosion is generally used to open fluid inclusions, and the gaseous-phase composition of the inclusions is analyzed past GC. Dan Yang et al. reported the application of a modified GC, GC-2010 (run into Fig. 3.12). Two-dimensional GC with a double column and double detector in series was established to accurately make up one's mind H₂, O_two, Northward₂, and methane in fluid inclusions.

Figure iii.12. Diagram of the modified gas chromatograph GC-2010. TCD, thermal conductivity detector.

According to Yang D, Xu Due west, Cui Y. Determination of gaseous phase components in fluid inclusions by two-dimensional gas chromatography. Rocks Miner 2007;26(half dozen):451–4.

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Methods including biomarkers used for detection of disinfection by-products

Manish Kumar , ... Pooja Devi , in Disinfection By-products in Drinking Water, 2020

17.ii.iii Gas chromatography–mass spectrometry

Gas chromatography (GC) has been traditionally used in the identification and quantification of volatile and semivolatile DBPs. Chemical derivatization of the target analytes that are usually polar, thermally labile, or hydrophilic, is necessary. Detectors such as electron capture detection (ECD) and MS are predominantly used in the GC analysis of DBPs similar HAA ( Hodgeson et al., 1995). Due to its high sensitivity, ECD is used for the quantification of targeted DBPs. ECD is used in standard methods, such as U.South. EPA methods 551.1 for determination of chlorination of DBPs and 552.3 for decision of haloacetonitriles, THMs, chloral hydrate etc. (Domino et al., 2003; Ding et al., 2018). In addition to this it has also been used to measure emerging DBPs viz haloacetamides in h2o matrices (Zeng et al., 2016; Allen et al., 2017). As ECD has high sensitivity for halogenated complexes, some DBPs or other organic compounds may influence the target analytes. In contempo years, researchers used a combination of single ion monitoring and MRM to identify 61 DBPs by GC-MS (MS) method. Prior to this, On et al. (2018) developed a dispersive liquid–liquid microextraction technique for identifying the 11 emerging DBPs by GC-MS. Furthermore, one of the most ubiquitous ionization technique for GC-MS analysis is electron ionization (EI), which uses a standardized ionization free energy approximately seventy   eV and results in a fragmentation design that is useful for the comparison fragment to library databases also as standard interpretation and identification of new DBPs (Ma et al., 2016; Zhang et al., 2016). Based on the method, Zhang et al. (2018) identified a new grouping of nitrogenous DBPs, chlorophenyl acetonitriles and confirmed their identities on the basis of retention time and fragment ions of analytes compared with the standards. Very recently, Kimura et al. (2019) used GC-time-of-flight (TOF)-MS and invented a technique for the quantification of 39 target DBPs equally well as for the extensive identification of nontarget DBPs such equally trans-two,3,4-trichloro-2-butenenitrile. In some studies, it has been seen that electron ionization (EI) fragments the molecules and then intensely that no molecular ion is present in the mass spectrum, which makes it difficult to fully identify these unknowns. Chemical ionization (CI) takes care of the pseudo-molecular ion with minimal fragmentation. Daiber and other studies found that the combination of EI and CI in GC-60 minutes-TOF-MS is capable of identifying a new series of sulfur-containing bromo-DBPs in pond pools and spas treated by bromine disinfection (Daiber et al., 2016; Nihemaiti et al., 2017; Liberatore et al., 2017).

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Green Gas and Liquid Capillary Chromatography

Heba Shaaban , ... Tadeusz Górecki , in The Application of Light-green Solvents in Separation Processes, 2017

15.three.one Selection of an Appropriate Carrier Gas

Selection of GC carrier gas is an important step in greening GC. The most commonly used gas in GC is helium because it is inert, nontoxic, nonflammable, and provides high optimum linear velocity; notwithstanding, this precious gas is a nonrenewable resource [12]. Nitrogen is too a common carrier gas in GC; the main drawback of this gas is its lower optimal linear velocity compared to helium or hydrogen, leading to longer analysis times. This makes nitrogen the least desirable carrier gas in GC [12]. On the other manus, hydrogen provides a flat van Deemter bend, assuasive the apply of catamenia rates college than the optimum without a meaning loss in efficiency. Consequently, loftier-throughput GC analysis could be accomplished without sacrificing resolution and efficiency. These advantages make hydrogen the best carrier gas for "light-green" GC.

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Technologies for detection of HRPs in wastewater

Yan Zhang PhD , ... Huajin Zhao , in Loftier-Risk Pollutants in Wastewater, 2020

4.2.3 Gas chromatography–mass spectrometry

GC–MS is a combination of a gas chromatograph and a mass spectrometer. Mass spectrometry tin can perform qualitative analysis, but it is powerless for the analysis of complex organic compounds; chromatography is an constructive separation method for organic compounds, peculiarly suitable for quantitative analysis of organic compounds, merely it is difficult to use chromatography for the qualitative analysis. Therefore, the combination of these two techniques can efficiently and quantitatively analyze complex organic compounds in wastewater.

GC–MS is the mainstream technology for the assay of volatile and semivolatile pollutants in wastewater. It has the advantages of strong separation ability, large peak capacity, and high detection sensitivity. GC–MS not just can detect traditional volatile and semivolatile pollutants, just also can play an essential role in the analysis of persistent organic pollutants, such every bit dioxins, polychlorinated biphenyls (PCBs), brominated flame retardants, polychlorinated naphthalenes, perfluorosulfonates, amides, perfluorotelomers, neutral perfluorinated compounds, short-chain chlorinated paraffins, environmental endocrine disruptors, sunscreens, and constructed musk. Yet, compounds such as organic acids would exist too reactive during the heating process of GC-MS. So, these compounds need to exist derivatized before the analysis. GC–MS cannot be used to determine the compounds that are neither vaporizable nor esterified.

Jillani et al. (2019) used GC–MS for the decision of PAHs from a local wastewater treatment plant in Kingdom of saudi arabia and the detection limits ranged from 0.29 to viii.four   ng/mL. Adeyinka et al. (2019) used GC–MS to detect OCPs in effluent from the Darvill Wastewater Handling Plant (WWTP) of Pietermaritzburg, South Africa. Adeyinka et al. (2018) detected PCBs in the effluent of wastewater treatment plant using GC–MS and the limits of detection ranged from 0.007 to 0.022   ng/50. Cuderman et al. (2007) applied GC-MS coupled with a series of preparation methods, including acidification, filtration, solid-phase extraction, and derivatization, to analyze UV filters and ii common antimicrobial agents, clorophene and triclosan in wastewater samples. By using these methods, the obtained limits of detection were thirteen–266   ng/L for UV filters, and 10–186   ng/L for triclosan and clorophene. Erarpat et al. (2018) adult an accurate and sensitive analytical method, namely switchable solvent-based liquid-stage microextraction combined with GC–MS, for the simultaneous determination of OCPs in a municipal wastewater sample collected from a biological WWTP. The obtained detection limit was 8.6   ng/mL.

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Organic Matter in Gas Shales

D. Mani , ... A.M. Dayal , in Shale Gas, 2017

three.4.three Closed System Pyrolysis

A closed system, offline pyrolysis of shales was performed to desorb the thermo-labile gases present in the rock matrix (Fig. 3.iv; Mani et al., 2015b). 500   mg of powdered shale was heated in the evacuated pyrolysis assembly at a fixed temperature of 300°C for 3   min (Fig. 3.four). Saturated KOH solution was added externally to a glass ampoule to absorb the carbon dioxide released during the pyrolysis of shales (Mani et al., 2015b). The thermally desorbed gases released during the pyrolysis were collected past upwardly displacement in the graduated limb of an appliance fitted with a silicone septum. The desorbed gases were analyzed for their stable carbon isotope ratio compositions (Mani et al., 2015b).

Figure 3.4. A schematic of the offline pyrolysis assembly used for collecting the thermo-labile gases from shales.

3.4.3.1 Gas Chromatography

Gas Chromatography (GC) is used for the qualitative and quantitative identification of chemical compounds and substantially includes the separation and identification of chemic mixtures ( Grob, 2004; Mani et al., 2015a). It consists of three main components: ane) an injector, which is a port meant for injecting the samples into the GC, 2) a column in which the analyte gets separated into private components, depending upon its affinity with the stationary phase and the mobile carrier gas phase, and 3) the detector, where the composition and concentration of the analyte are adamant (Mani et al., 2015a). The molecules of the analyte are partitioned between the stationary phase nowadays in the column and the mobile phase of the carrier gas. A carrier gas is an inert gas such equally nitrogen or helium that carries the sample through the column to the detector. The column comprises the stationary phase, which is made up of polymeric material (Mani et al., 2015a). It is kept in a heated oven for maintaining the cavalcade temperature. Depending upon analyte composition, different types of columns, such as capillary or packed, with specific polymers are used. The components are eluted by the mobile phase. They accomplish the detector at different times, which is very specific for each component under a particular condition of pressure and temperature. It is called the retention fourth dimension (Rt) of a respective component (Mani et al., 2015a). The hydrocarbon concentration is detected using the FID. Here, the organic compounds are burnt in a flame of hydrogen and air. A collecting electrode collects the electrons produced during combustion. The resulting electric current is the response of the detector in the grade of series of betoken peaks. The concentration is adamant using the peak expanse or summit meridian every bit ground (Grob, 2004; Mani et al., 2015a). The GC, when hyphenated with a mass detector, becomes a more than powerful technique for trace level organics in sediments than GC-FID.

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Pesticides and herbicides in nonsaline waters

T.R. Crompton , in Determination of Toxic Organic Chemicals in Natural Waters, Sediments and Soils, 2019

Gas chromatography

GC is the preferred method for detecting triazine herbicides. McKone et al. [306] compared GC methods to detect atrazine (2-chloro-iv-ethylamino-6-isopropyl-amino-1,iii,five-triazine), ametryne (2-ethylaminio-4-isopropylamino-6-methylthio-1,iii,five-triazane) and terbutryne in h2o. The herbicides were extracted from water with dichloromethane, and the dried extracts were evaporated to dryness at a temperature below 35°C. The three herbicides were separated by GC on a glass column (i   thousand×four   mm) of 2% neopentyl glycol succinate on Chromosorb Westward (fourscore–100   mesh) operated at 195°C with a RbBr-tipped flame ionisation detector. The researchers detected 0.001   ppm of each herbicide. This method was superior to spectrophotometric methods.

Purkayastha and Cochrane [307] compared electron-capture and electrolytic conductivity detectors in the gas chromatographic determination of prometon, atraton, (two-thylamino-4-isorpopylamino-6-emthoxy-i,3,five-triazine), propazine, atrazine, (2-chloro-4-ethylamino-6-isopropylamino-1,iii,5-triazine), prometryne, simazine (two-chloro-4, 6-bis-ethylamino,i,three,5-trianxine) and ametryne (ii-ethylamino-4-isorporpylamino-6-methylthio-,1,3,five-triazine) in inland water samples. They establish that the electrolytic electrical conductivity detector had a wider awarding than a ⁶³Ni electron-capture detector. Use of the ⁶³Ni electron-capture detector necessitated a clean-upwardly stage for all the study samples. The electrical conductivity detector could be used in water assay without sample clean-up. The researchers observed efficient recoveries of atrazine added to water by extraction with dichloromethane.

Ramsteiner et al. [308] compared alkali flame ionisation microcoulmometric, flame photometric and electrolytic conductivity detectors to determine the presence of triazine herbicides in h2o. The researchers cleaned methanol extracts on an alumina cavalcade and detected 12 herbicides by GC with conventional columns containing three% Carbowax 20M on fourscore–100   mesh Chromosorb M.

Hormann et al. [309] monitored diverse European rivers for levels of atrazine, terbumeton, dealkylated metabolites GS26571 (two-amino-4-tertbutylamino-5-methoxy-1,3,5-triazine) and GS30033 (2-amino-4-chloro-5-ethylamino-ane,3,5-triazine). The compounds were extracted into dichloromethane and quantitated by GC with nitrogen-specific detection. Selected results were verified by GC with mass fragmentographic detection. The limit of detection was usually 0.4   µg   L⁻¹.

The US Environmental Protection Agency [305] issued a gas chromatographic method to determine the post-obit herbicides at the microgram per litre level in water and waste h2o: ametryne, atraton, atrazine, prometon, prometryne, propazine, secbumeton, simazine and terbutylazine. The method described an efficient sample extraction process and provided a method to eliminate nonpesticide interferences and prepared pesticide mixtures using cavalcade chromatography. Identification was fabricated by nitrogen-specific gas chromatographic separation, and measurement was accomplished with an electrolytic electrical conductivity detector or a nitrogen-specific detector. Steinheimer and Brooks [310] developed a multiresidue method for the simultaneous conclusion of seven triazine herbicides in surface and ground water with a detection limit at the micrograms per litre level. The technique used solvent extraction, gas chromatographic separation and nitrogen-constituent detection devices. The researchers examined solid-phase extraction techniques using chromatographic grade silicas with chemically modified surfaces for three natural water samples. Solid-stage extraction was found to produce a rapid and efficient concentration with quantifiable recovery. Solid-phase extraction was presented as an alternative to liquid–liquid partition.

Jahda and Marha [311] investigated the isolation of s-triazines from water using continuous steam-distillation extraction followed by gas–liquid chromatography. They report the recovery of vii triazine herbicides from water at pH values of 5.vii and 9: propazine, tertbutylazine, atrazine, prometryne, terbutryne, desmetryne and simazine. Recovery rates were independent of pH merely generally improved when steam-distillation extraction time was increased from one to 3   hours. Depression recovery rates were obtained for simazine. Atrazine only produced decent recovery rates later on 3   hours of steam-distillation extraction.

Lee and Stokker [312] developed a multiresidue procedure for the quantitative determination of 10 triazines in natural waters past GC using a nitrogen–phosphorus detector. The researchers analysed ametryne, atraton, atrazine, cyanazine, prometon, prometryne, propazine, simazine, simetone and simetryne. All compounds were successfully quantified on the Ultrabond 20   M and 3% OV-one columns. Extraction was by methylene chloride and clean-upward was by florisil. Recoveries of triazines at ten, 1.0 and 01   µg   L^−ane were between 87% and 108%, and simetone and simetryne at 0.1   µg   Fifty⁻¹ were just eighty%.

Isotope dilution GC–MS was used [313] to observe 0.i–1   µg   Fifty⁻ⁱ of atrazine, lindane, diazinon and pentachlorophenol in natural water. An accuracy of 86% and a precision of 8% were demonstrated.

Zangwei et al. [314] determined atrazine in water at sub-ppt levels using solid-phase extraction and GC–high-resolution MS. They used a C₁₈-bonded cartridge followed by column chromatography on florisil to remove interfering substances.

Deleu and Copin [315] used GC–MS to determine the presence of atrazine in water down to 0.i   µg   L⁻¹.

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Integrated Sand Management For Effective Hydrocarbon Catamenia Assurance

Babs Oyeneyin , in Developments in Petroleum Science, 2015

Molecular Weight Distribution

Gas chromatography (GC) or gel permeation chromatography (GPC) is used to identify the paraffin molecular weight distribution in the crude oil. The proportions of n-alkanes, iso-alkanes, cyclo-alkanes, naphthalenes, asphalts, etc., can exist estimated, although it becomes more than difficult to differentiate the many isomers for carbon number C7 and higher up. The weight percent of C18  + fractions and therefore the wax content can exist estimated from the chromatograms. A typical graph of distribution of different hydrocarbon chain lengths is given in Effigy 2.32.

Figure two.32. Typical northward-Alkane Distribution of Dead Rough.

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Physics of Terrestrial Planets and Moons

P. Falkner , R. Schulz , in Treatise on Geophysics (Second Edition), 2015

x.23.4.14.5 Gas chromatograph–mass spectrometer

Gas chromatography–mass spectroscopy (GCMS) is used to measure out abundances and isotopic ratios of noble gases (He, Ne, Ar, Kr, and Xe) and the abundances of minor gas constituents like SO ₂, COS, CO, HCl, H₂S, and H_iiO (nonexhaustive) in planetary atmospheres. A pump system controlled with valves is used to generate a low gas catamenia rate at a reduced pressure to obtain new gas samples from the ambience atmosphere, which are combined with a carrier gas (such as hydrogen) and injected into the gas chromatograph (GC). The GC section provides a fourth dimension-dependent separation of the gas components prior to a molecular identification in the mass spectrometer (MS). The output of the GC section is ionized with, for case, electron bear upon ionization before arriving in a quadrupole mass filter, followed by an ion detector. But other methods for the MS can be used as well.

Gas chromatograph–mass spectrometer systems are powerful analytic tools for chemic analysis of many compounds and especially of gas mixtures, but relative circuitous instruments. GCMS instruments have been flown, for case, on Huygens (Niemann et al., 2002) and the Rosetta lander Philae (Goesmann et al., 2006; Wright et al., 2006) or more than recently on the MSL mission (Mahaffy and The SAM Team, 2011).

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Measurement and Monitoring of Mine Gases

Pramod Thakur Ph.D. , in Advanced Mine Ventilation, 2019

19.4.3 Gas Chromatography

Gas chromatography, with regard to gas analysis, involves the separation of all sample components followed past their measurement on relatively nonspecific detectors. Specificity is obtained by virtue of the separation process rather than detection.

The use of a GC expands analytical capabilities to include gases crucial in the estimation of spontaneous combustion events, particularly ethylene and hydrogen. The GC provides a consummate assay of the gases expected underground and is the only i of the iii techniques capable of measuring hydrogen, nitrogen, ethylene, and ethane. Determination of nitrogen is especially important for determining oxygen deficiency in some spontaneous combustion indicating ratios (refer to Chapter 21).

Similar to the tube package, problems exist with bringing the samples to the GC. The significance of time delays in getting results is dependent on what the results are beingness used for. GC is not going to be suitable for detection of a belt burn because of the time delay between collection of the sample and analysis, simply the delay is acceptable for confirmation of other results or for bear witness and trending of spontaneous combustion indicators.

Like the tube parcel organization, the gas matrix of the sample does non affect GC assay. Then long equally appropriate scale gases are bachelor, this technique is capable of measuring gases at any concentration in a higher place their detection limit. This eliminates the bug seen with the other techniques, especially for carbon monoxide concentrations greater than 1000   ppm.

The ultrafast GCs in use in Australian mines permit the assay of most of the components expected underground in approximately 2   minutes.

This increased speed of analysis is invaluable during emergency situations, especially when assessing the safe of the underground atmosphere for reentry or during reentry by mine rescue teams. In these cases, what makes this assessment more effective is that GC is on-site and tin can be operated by mine personnel. There is no delay in determining the status underground, while waiting for external providers to get in or transporting samples away from site for laboratory analysis.

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