APPLICATIONS OF GAS CHROMATOGRAPHY [APPLICATIONS OF GC] BY Prof. Dr. P.RAVISANKAR.

APPLICATIONS OF GAS CHROMATOGRAPHY [APPLICATIONS OF GC] BY Prof.Dr.RAVISANKAR
VIGNAN PHARMACY COLLEGE, VADLAMUDI, GUINTUR,A.P, INDIA.

1. APPLICATIONS OF GAS CHROMATOGRAPHY (GC) Prof. Dr . P. Ravi Sankar , M.Pharm .,Ph. D B. Sindhura M. Pharm Vignan Pharmacy college Vadlamudi Guntur Dist. Andhra Pradesh India. [email protected] [phone]

2. APPLICATIONS OF GAS CHROMATOGRAPHY G as chromatography (gc) is an instrumental technique used forensically in drug analysis, arson, toxicology analyses of other organic compounds. T he gc is one of popular instrument used in the world several (applications) advantages include: High speed analysis in a matter of minutes and routine and less few analysis in a matter of few seconds also possible and we see also both rapid analysis as well as high sensitivity. F or example is a 2 1/2 min of separation three common pesticides like methyl parathion, malathion, ethion at pg levels. pg means 10 -12 grams these are parts per billion. this is very good example of both the high speed as well as a very sensitive detection.

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4. USES : Petroleum products, waxes, solvents, hydrocarbons, highly volatile solvents.

5. COMMON APPLICATIONS : Quantification of pollutants in drinking and waste water using official U.S. Environmental Protection Agency ( EPA) methods. Quantification of drugs and their metabolites in blood and urine for both pharmacological and forensic applications. Identification of unknown organic compounds in hazardous waste dumps. Identification of reaction products. Analysis of industrial products for quality control. ANALYSIS OF VOLATILE ORGANIC COMPOUNDS IN INDOOR AIR

6. Gas chromatography is a physical separation method in where volatile mixtures are separated. It can be used in many different fields such as pharmaceuticals, cosmetics and even environmental toxins. Since the samples have to be volatile, human breathe, blood, saliva and other secretions containing large amounts of organic volatiles can be easily analyzed using GC. Knowing the amount of which compound is in a given sample gives a huge advantage in studying the effects of human health and of the environment as well.  Air samples can be analyzed using GC. Most of the time, air quality control units use GC coupled with FID in order to determine the components of a given air sample. Although other detectors are useful as well, FID is the most appropriate because of its sensitivity and resolution and also because it can detect very small molecules as well. GC/MS is also another useful method which can determine the components of a given mixture using the retention times and the abundance of the samples. This method be applied to many pharmaceutical applications such as identifying the amount of chemicals in drugs. Moreover , cosmetic manufacturers also use this method to effectively measure how much of each chemical is used for their products. 

7. GC and liquid chromatography together just been the premier technique for trace analysis of organic and inorganic compounds. If I think all the work which is been done in air pollution and water pollution and food safety. we have to analyze pesticides toxic chemicals founds in food and food products W e have to analyze the pesticide and food safety and toxic chemicals and food Products and all of these things are daily and rapidly by GC and or liquid chromatography .

8. Chemical analysis GC Analysis of Xylene Isomers on SLB ® -IL60 application for GC The xylene isomers are precursors to many chemicals: • o-xylene is a precursor for phthalic anhydride • m-xylene is a precursor for isophthalic acid • p-xylene is a precursor for terephthalic acid and dimethyl terephthalate The cresol (methyl phenol) isomers are also precursors to many chemicals. This chromatogram of a mix of aromatic and methyl phenol compounds was generated using an SLB-IL60 ionic liquid column. Its interaction mechanisms allow the separation of all three xylene isomers, and all three cresol isomers.

9. Related Categories Analytical/Chromatography , Applications , Aromatics , Capillary GC Columns and Guard Columns/Retention Gaps , Capillary GC Columns, by industry / application , Capillary GC Columns, by name , Capillary GC Columns, by phase polarity , Chromatograms , Compound Class , GC Applications , GC Columns for the Chemical Industry , Gas Chromatography (GC) , Hydrocarbons , Ionic Liquid Capillary GC Columns , Polar Capillary GC Columns , SLB-IL60 , Xylene Isomers Less... test parameters   column: SLB-IL60, 30 m x 0.25 mm I.D., 0.20 μm (29505-U)   oven: 40 °C (4 min), 8 °C/min to 200 °C (5 min)   inj. temp.: 250 °C   detector: FID, 250 °C   carrier gas : 30 cm/sec constant pressure   injection: 1  μ L100:1 split   liner: 4 mm I.D., split/ splitless type, wool packed single taper FocusLiner ™ design   sample: 12 analytes, each at 0.2% (v/v) in pentane suitability   application for GC Featured Industry   Chemicals and Industrial Polymers

10. Peak formation of xylene isomers:

11. Separation of m - and p - Xylenes by Gas Chromatography on Dimethyl Polysiloxone. Short piece of 5% diphenyl 95% dimethyl column connected to a wax column.  Cryofocusing was done on the 5 (which still has some diffusivity at -80°C) and rapid heating to 40°C restored the wax to a “liquid” to allow the efficient separation of m- and p-xylenes. A wax is one of the only commercially-available capillary GC stationary phases that will separate m- and p- xylenes.  

12. Analysis of p-Xylene by GC-FID using a HP-INNO Wax column The purity of solutions, from relatively pure solvent such as xylene, to liquors such as scotch can be also be determined by GC. Two examples are shown below. Analysis of Minor Components of Scotch by GC-FID using a HP-101 Column

13. One of the aspects of my job that I really enjoy is explaining the science of Blood Alcohol Concentration and/or reported levels of Drugs of Abuse to normal everyday folks, judges, jurors, prosecutors and even fellow attorneys . One of the most common questions I get asked is in the area of gas chromatography. Just yesterday a colleague from Texas called me up to help him interpret a Gas Chromatography result. He asked: How do they make the squiggly lines [of a chromatogram] turn into a magic number [the reported BAC]? It’s a great question. In essence, how do we take the electrical signal output from the detector and resolve that raw data into reported quantified result for our analyse of interest? In chromatography and in particular when a Flame Ionization Detector is used as the quantifying device, the method that we use to arrive the ultimate reported result is a product of the peak of the chromatogram. The peak height, the peak shape and the peak area are important .

14. Petroleum product analysis GC Analysis of Small Molecules in Jet Fuel on Supel-Q ™ PLOT application for GC Properties Related Categories Analytical/Chromatography , Applications , Capillary GC Columns and Guard Columns/Retention Gaps , Capillary GC Columns, by industry / application , Capillary GC Columns, by name , Chromatograms , Compound Class , GC Applications , GC Columns for the Petroleum Industry , Gas Chromatography (GC) , Hydrocarbons , Impurities in Fuel , PLOT Capillary GC Columns , Supel -Q PLOT Less... test parameters   column: Supel -Q PLOT   oven: 35 °C (3 min), 16 °C/min to 250 °C   detector: TCD   carrier gas: helium, 3.0 mL/min   sample: Jet fuel suitability   application for GC Featured Industry   Petroleum

15. GC Analysis of Water in Gasoline on Supel-Q ™ PLOT application for GC Related Categories Analytical/Chromatography , Applications , Capillary GC Columns and Guard Columns/Retention Gaps , Capillary GC Columns, by industry / application , Capillary GC Columns, by name , Chromatograms , Compound Class , GC Applications , GC Columns for the Petroleum Industry , Gas Chromatography (GC) , Hydrocarbons , Impurities in Fuel , PLOT Capillary GC Columns , Supel -Q PLOT Less... test parameters   column: Supel-Q   oven: 35 °C (3 min), 16 °C/min to 250 °C   detector: TCD   carrier gas: helium, 3.0 mL/min   sample: Gasoline suitability   application for GC Featured Industry   Petroleum

16. One advantages of adsorption ( GC) chromatography, as is also true for GSC, is that it is able to retain and separate some compounds that can not be separated by other methods. One such application is in the separation of geometrical isomers.

17. Primary column: Fused silica 30m by 0.25 mm ID. 5% diphenyl, 95% dimethyl polysiloxone stationary phase having 0.25 micrometer film thickness . Secondary column: Fused silica 30m by 0.25mm ID internally coated with 14 % cyanopropyl phenyl and 86% dimethyl polysiloxone stationary phase having 0.25 µm film thickness. The role of modulator is to collect fractions from chromatographic technique. It employs 2 columns in series separated by a modulator. The role of modulator is to collect the fractions from first column often called as First dimension column or Primary column or 1 o column and then focus on to the Secondary column or 2 column. Primary column tend to be 30m X 0.25mm ID. Secondary column tend to be 1-2m X 0.10mm ID.

18. DETERMINATION OF PESTICIDES RESIDUE IN AQUACULTURE PRODUCTS DETECTION AND QUANTITATION BY GAS CHROMATOGRAPHY Agricultural chemicals such as fertilizers and pesticides have made an important contribution to agriculture . Pesticides protect crops from pests and diseases. They have brought about large yield increases. Since almost all chemicals that can kill pests are also potentially damaging to human health . Legislation requires that pesticide use is appropriately controlled and maximum residue levels (MRL) not be exceeded. Detection method is the process of identifying the pesticides and determining their concentrations with the aid of an analytical instrument, such as a gas chromatograph (GC), we can obtain information about the original sample by running a standard solution containing the pesticide(s) at a known concentration and comparing it with the sample .

19. GC Analysis of Pesticides in Grapes on SLB ® -5ms after QuEChERS Cleanup using Supel ™ QuE PSA/C18 application for GC, application for SPE

20. Related categories Analytical/chromatography, applications, capillary GC column, guard column/ retention caps, capillary GC column, by industry/applications. Test parameters Sample preparation : dispersive (QuEChERS). Sample/matrix : Thomson green seedless table grapes. extraction tube : supel QuE Acetate extraction tubes (55234-U). extraction process : add 15 ml of acetonitrile with 1% acetic acid; shake for 1 min; add contents of supel QuE acetate extraction tubes; shake at 2500 rpm for 10 min. clean-up tubes: supel QuE PSA/C18 suitable for 2007.01 per AOAC(55288-U). Clean up process : transfer 1ml of acetonitrile layer into cleanup tube; shake for 1 min ; centrifuge at 5000 rpm for 3 min; draw off supernatant for LVI-GC/MS analysis. Column : SLB-5ms, 20*0.18µm(28564-U). Oven : 50 ֯ c (2.9 min), 8 ֯ C/min to 330 ֯ C. Inj. temp : programed 50 ֯ C (0.4min), 600 ֯ C/min to325 ֯ C (5min). Detector :MS-SIM. MSD interface : 330 ֯ C. Scan range : SIM. Carrier gas : helium, 0.7 mL/min constant flow. injection: 10 μL PTV; 100 mL/min vent flow (5 psi) until 0.4 min, purge flow to split vent 60 mL/min at 2.9 min. liner: 4 mm ID Focus Liner w/taper . Suitability . Application for GC. Application for SPE. Featured industry. Agriculture Food and Beverages

21. GAS CHROMATOGRAPHIC CONDITIONS Gas chromatograph Model: Shimadzu GC-17A, equipped with 63 Nielectron capture detector, attached to a CBM-102 Chromatopak recorder system. Detector: Electron capture detector (ECD) Column: SPB-608 (Supelco), Capillary (Fused silica), 30m X 0.25mm I.D ., 0.25 um film Column Oven Temperature: 150°C (4 min) to 290°C at 8o C/min, hold 10 min . Detector temperature: 300 o C Injector temperature : 220 o C Carrier gas: Nitrogen (N 2 ) at f low rate of 40 cm/sec . Measure the area or height of residue peak(s) and determine the residue amount by comparison to peak area or height obtained from a known amount of appropriate reference material(s).

22. Determination of the VOCs toluene , ethylbenzene, o-xylene and cumene (TEXC) in air analysed and quantified using a gas chromatograph with flame ionisation detection (GC-FID). Volatile organic compounds (VOCs) are a cause of concern for human health due to their increased presence in the indoor environment. They are responsible for a phenomenon known as the sick building syndrome (SBS ). Air monitoring is being used to assess indoor pollution.

23. The pharmaceutical industry also heavily uses GC and HPLC to determine the purity of reagents, the identity of synthesis products, and the identity of medicines and illicit drugs. A few examples are shown below: In most forensic applications of GC, a sample is prepared by dissolving it in a solvent, and the solution is injected into the instrument using a syringe. For example, to analyse a white powder suspected of being cocaine, a small portion is weighed out and dissolved in a solvent such as methylene chloride, methanol, or chloroform . A tiny portion of the sample is then drawn up into a syringe and injected into the heated injector port of the instrument. The mobile phase gas (called the carrier gas) also enters the injector port, picking up the volatilized sample and introducing it into the column where the separation process occurs . If the sample contains cocaine, it will emerge from the column at a given time (known as the retention time) that can be compared to the retention time of a known standard sample of cocaine. The retention time in conjunction with information obtained from the detector is used to positively identify the compound as cocaine if indeed it is present . Another method of sample introduction for GC is called pyrolysis, in which a solid sample such as a fiber or paint chip is heated in a special sample holder to extreme temperatures, causing the sample to decompose into gaseous components that can then be introduced into the GC . Pyrolysis is used when the sample is not readily soluble in common GC solvents .

24. GC-MS USED IN THYROID CANCER STUDY Gas chromatography-Mass spectrometry (GC-MS ) has been used to investigate the pathogenic differences in a form of cancer according to gender and menopausal condition . In a study published by BMC(biomed central services publish original research on oncology). Cancer, scientists sought to evaluate the metabolic changes in urinary steroids in men and pre and post-menopausal women with papillary thyroid carcinoma (PTC). GC-MS was used to measure the urinary concentrations of 84 steroids in all of the patients against corresponding controls . The metabolic ratio of 2-hydroxy estrone to 2-hydroxy-17 beta-estradiol in particular showed gender differences in PTC patients . It is hoped the findings could help better understand the pathogenic differences in PTC according to gender and menopausal conditions .

25. Gas chromatography (GC) is the most common method for analysing phytosterol content and composition . There are HPLC methods available for separating and quantifying the various forms of phytosterols, such as free sterols, steryl fatty acid esters, steryl glycosides, acylated steryl glycosides, and hydroxycinnamic acid esters of sterols [1,10]. However, with over 200 different structures, GC, often combined with mass spectrometry, is the best and most widely used tool for the chromatographic separation, identification, and quantification of phytosterol qualitative and quantitative analysis of phytosterols in food products. Therefore, GC-mass spectrometry (GC-MS) is a valuable aid for identifying unknown phytosterol peaks as well as for confirming the identification and purity of identified phytosterol peaks are identified using flame-ionization detection (FID) by comparing the retention times (RT) of sterol peaks to that of pure standards. A few sterol standards including cholesterol and cholesterol derivatives and analogues, campesterol, campestanol, stigmasterol, sitosterol, sitostanol, brassicasterol, fucosterol, cycloartenol, and ergosterol are available from commercial vendors such as Sigma,

26. Plant sterols (phytosterols) are ubiquitous in plants The most common phytosterols have a double bond at position 5 of the B-ring, (commonly referred to as Δ5), however, Δ7-phytosterols are also found in many seed oils, while cereals such as corn, wheat, rice, rye Phytosterols are well-known for their ability to lower blood cholesterol by competing with absorption of cholesterol from the diet and reabsorption of bile cholesterol

27. 2 . High resolution: Many compounds can be resolved nicely. For ex: gasoline has been resolved in to over 300 different peaks complex sample of Petroleum Oil refinery – separates fractions of oil for petroleum products.

28. Natural Gas GC can also be used to determine the identity of natural products containing complex mixtures of similar compounds . For example, the geographic source of crude oil or natural gas can be determined by the “fingerprint”, or relative distribution of major and trace compounds in each oil . Natural produce oils, such as food products or fragrances, can be identified by GC-FID or GC-MS . A few examples of the separation of these complex mixtures are shown below.

29. Barbiturates are a class of compounds that are central nervous system depressants. They are categorized as sedatives or hypnotics and are primarily used in the treatment of anxiety, insomnia , and convulsive disorders. Barbiturates can be analysed in either their underivatized or derivatized forms by gas chromatography. Derivatization of the barbiturates is most commonly performed by methylation of the amido nitrogens in positions 1 and 3. Methylating reagents like tetramethylammonium hydroxide (TMAH) and trimethylanilinium anilinium hydroxide (TMPAH) can be used . Analysis of barbiturates can also be performed on underivatized compounds. However, underivatized barbiturates have a tendency to produce overloaded or tailing peaks. Maintain injection port liners, guard columns, and analytical columns regularly to achieve good peak shape and adequate resolution .

30. Analysis of Anticonvulsants by GC-FID using an HP-1 column. Source : Agilent Technologies.

31. BARBITURATE ENANTIOMERS APPLICATION FOR GC : One enantiomer in the mixture may have an activity or toxicity ... Out of the many chiral complexing agents used to separate chiral drugs by gas chromatography ( GC ). Description (±)- Mephobarbital Hexobarbital carrier gas : helium, 20 cm/sec @ 275 °C column : β-DEX 120, 30 m × 0.25 mm I.D., 0.25 μm (24304) det. : FID, 300 °C inj. : 300 °C injection : 100:1 split oven : 210 °C

32. ANALYSIS OF ALKALOIDS AND BARBITURATES BY GC-FID WITH AN ULTRA 2 COLUMN.

33. ANALYSIS OF PEPPERMINT OIL BY GC-FID USING AN HP-INNO WAX COLUMN

34. Chlordiazepoxide is a long acting benzodiazepine drug. The half-life of Chlordiazepoxide is 5 – 30 hours but has an active benzodiazepine metabolite (desmethyldiazepam) which has a half-life of 36 – 200 hours. A rapid gas chromatographic method for the determination of diazepam and metabolites in body fluids. A rapid method is described for the extraction of diazepam and its metabolites from plasma and urine. The procedure is applicable to subsequent analysis by electron capture gas chromatography, and has been used for the analysis of clinical samples. The detection limit for diazepam is about 0.01 μg/ml .

35. NOVEL APPLICATIONS IN GAS CHROMATOGRAPHY DETECTION OF ARSON ACCELERANTS USING GAS CHROMATOGRAPHY Arson studies: Gas chromatography – mass spectrometry (GC/MS ) is a well established method for analysis of ignitable liquids . According to the  US Fire Administration, arson is the leading cause of fires and the second leading cause of deaths and injures, and that’s why arson investigation is of forensic significance for the criminal justice system. Commercially available fuels or solvents that are mixtures consisting of hundreds of components are typically used to start a fire. Analysis becomes very difficult because ignitable liquids consist of same or similar components at different concentrations, in addition, fire may evaporate some of the components and thus altering the composition of residual ignitable liquids found in fire debris. Analysis, detection, and identification of accelerants in arson studies are indeed applicable in gas chromatography.

36. BLOOD ALCOHOLS (PACKED APPLICATION GC ) The determination (accurately measure)of blood alcohol content (BAC) is one of the most common tests performed by forensic laboratories . Blood alcohol analysis is used by law enforcement to determine if a driver was unlawfully operating a vehicle. The results will be used in a court of law, therefore it is important to minimize systematic and operator errors . This application note presents the details of an optimized column separation method for the determination of ethyl alcohol, the internal standard propyl alcohol, three other common alcohols , and many potentially interfering common volatiles present in samples being analysed for measures of driving under the influence of alcohol" (DUI )acronym used in many regulating districts ). This possible method for determining forensic blood alcohol concentrations. carrier gas : helium, 20 mL/min. column : 6 ft. × 2 mm I.D. glass det . : FID injection : 1 μL oven : 85 °C packing : 5 % Carbowax 20M on 60/80 Carbopack B Determination of alcohol (i.e. ethanol) in blood or urine. One obvious application is when law enforcement agencies need to determine whether or not someone is inebriated. In these cases, high sensitivity is required since 0.1% blood alcohol content is considered to be legally intoxicated in most states .

37. We take the area under the peak, then apply that numeric to the calibration curve to arrive at the reported result . The peak shape should be Poisson, Gaussian or close to Gaussian. [ Blogger’s note: in Wednesday’s post we will describe what consequences can occur if it is not ] A calibration curve is simply a graph where concentration is plotted along the x-axis and area is plotted along the y-axis. [See the previous post about calibration curves-When is a straight line a curve: Calibration curve] Figure 2 is an example of a calibration curve for a hypothetical compound X. It was created by running 5 different calibration standards (5, 10, 15, 20, 25 g/mL). Each concentration gave a peak area (5000, 10000, 15000, 20000, 25000). Peak area was then plotted against the concentrations . Once we have constructed our curve, we can analyse our sample. We simply determine the peak area for the analyses in our sample, and then draw a line on the graph at that area (note the red arrows). When the calibration curve is reached, we drop a line down to the x-axis. That will give us the concentration of the analyses in our sample. This is why the area under the peak and peak shape is important in gas chromatography .

38. GC Analysis of Blood Alcohols in Human Plasma on SUPELCOWAX ® 10 after SPME using 60 μm Carbowax ® Fiber application for GC, application for SPME

39. Related Categories Alcohols , Analytical/Chromatography , Applications , Blood Alcohols , Capillary GC Columns and Guard Columns/Retention Gaps , Capillary GC Columns, by industry / application , Capillary GC Columns, by name , Capillary GC Columns, by phase polarity , Chromatograms , Clinical, Forensic, Bioanalytical , Compound Class , Drugs & Pharmaceuticals , Drugs of Abuse , GC Applications , GC Columns for the Forensic Industry , Gas Chromatography (GC) , Polar Capillary GC Columns , SPME Applications , SUPELCOWAX 10 Less... test parameters   sample/matrix: blood alcohols at concentrations indicated in human plasma   SPME fiber: 60 μm Carbowax   extraction: headspace, 50 °C (5 min)   desorption process: 220 °C, 2 min   column: SUPELCOWAX 10, 30 m × 0.25 mm I.D., 0.50 μm (24284)   oven: 35 °C (2 min), 10 °C/min to 125 °C (1 min)   detector: FID, 200 °C   carrier gas: helium, 1.0 mL/min constant   injection: 10:1 split   liner: 0.75 mm I.D. SPME liner suitability   application for GC   application for SPME Featured Industry   Forensics and Toxicology Properties

40. RAPID METHOD FOR DETERMINATION OF ETHANOL IN ALCOHOLIC BEVERAGES USING CAPILLARY GAS CHROMATOGRAPHY Ethanol content is very important for the mouth-feel and flavour of alcoholic beverages. Ethanol contents of wine , liqueur, and beer range from 7~21%(v/v ), 20~50 %(v/v), and 3~6%(v/v), respectively (1 ). In general, ethanol contents serve as the quality index and taxation factor for alcoholic beverages(2). After entering WTO, alcoholic beverages in Taiwan are taxed according to the ethanol contents, like the taxation system in United States(3). The higher the ethanol content in an alcoholic beverage , the higher the tax. I t takes only 7~8 min to complete a sample analysis for the determination of ethanol content in a beverage sample. A sample solution (0.5 mL) is mixed with adequate amount (5 mL) of 1% (w/v) internal standard solution (acetonitrile, equivalent to 50 mg), and injected into a capillary GC .

41. BREATH ALCOHOL TESTING Drunk driving costs countless lives and destroys families around the world each year . In most countries drunk driving is illegal and in pursuing these laws the police utilizes breathalysers tests. Test equipment must be perfectly calibrated to stand up in a court of law. Therefore one of the calibration methods is to use a calibration gas. The demands on such a calibration gas are strict, it must be easy to use, be stable, portable and fool-proof . Linde produces and delivers such calibration gases with the breathable program. Determination of free cholesterol in milk fat: rapid and direct gas chromatographic (GC) method for determining free cholesterol in milk fat using a capillary column and programmed-temperature vaporizer injector was assayed . Soil and Water Measurement contamination of soil and water can come from many areas, including acid rain, pesticides industrial waste, landfill, and raw sewage. Analytical procedures include GC/MS .

42. Environmental measurement is accomplished in many ways. Air samples may be collected using sample bags or containers and analysed using gas chromatography. For example, with the US EPA CEMS have a requirement under some environmental regulations for either continuous compliance determination of the level in which the facility is out of compliance with acceptable emission standards.  In all areas, a variety of pure gases and calibration gas mixtures are required. Additionally, due to legal requirements, many of these gas mixtures will need to be accredited to international standards. Air Quality Monitoring International accords such as the Montreal protocol, or Kyoto accords call on all industry everywhere to monitor, control and reduce their emissions before discharging them into the environment . There are a number of different particulate and gaseous emissions which result from smoke stack emissions in many industries including  manufacturing, chemical and  petrochemical, and power generation.

43. AREAS OF KEY MEASUREMENT INCLUDE Carbon monoxide (CO) from industrial processes and incomplete combustion of wood, oil, gas and coal. Carbon dioxide (CO 2 ) , Sulphur Dioxide (SO 2 ), and Nitric oxides (NO and NO 2 ) from combustion of gas, oil and coal. Hydrogen sulphide (H 2 S) and methyl mercaptan (CH 3 SH) from pulp and paper mills. Hydrocarbons resulting from incomplete combustion of fuels. ISO 3930 requirements for vehicle exhaust emission levels for carbon monoxide (CO), carbon dioxide (CO 2 ), hydrocarbons (HC, in terms of n-hexane), and oxygen (O 2 ). In all areas, a variety of environmental  pure gases  and calibration gas standards  are required . Additionally, due to legislative, and/or legal requirements, many of these standards will need which need manufacturing to accreditation levels. 

44. FOOD PACKAGING Modified Atmosphere Packaging of food, or MAP, is a natural shelf-life-enhancing method that is growing rapidly on an international scale. It often complements other techniques, such as high-pressure and microwave methods or oxygen absorption. The correct gas mixture in MAP maintains high quality by retaining the original taste, texture and appearance of the foodstuff. On the other hand, should the product have a high fat content and low water activity, oxidation protection is most important and inert nitrogen would be the preferred choice. The gas atmosphere must be chosen with due consideration of the particular foodstuff and its properties. For low-fat products with a high moisture content, it is especially the growth of microorganism that has to be inhibited by using carbon dioxide

45. Food and beverages applications Foods and beverages contain numerous aromatic compounds, some naturally present in the raw materials and some forming during processing. GC is extensively used for the analysis of these compounds which include esters, fatty acids, alcohols, aldehydes, terpenes etc. It is also used to detect and measure contaminants from spoilage or adulteration which may be harmful and which is often controlled by governmental agencies, for example pesticides.

46. GC Analysis of Organic Acids on Nukol ™ application for GC

47. Related Categories Acids , Analytical/Chromatography , Applications , Capillary GC Columns and Guard Columns/Retention Gaps , Capillary GC Columns, by industry / application , Capillary GC Columns, by name , Capillary GC Columns, by phase polarity , Chromatograms , Compound Class , Fatty Acids , Free Fatty Acids , GC Applications , GC Columns for the Food & Beverage Industry , Gas Chromatography (GC) , Nukol , Organic Acids , Polar Capillary GC Columns Less... test parameters   column: Nukol , 15 m x 0.32 mm I.D., 0.25 μ m (24130)   oven: 80 °C (1 min), 15 °C/min to 200 °C (3 min)   inj. temp.: 250 °C   detector: FID, 250 °C   carrier gas: helium, 2 mL/min constant   injection: 1  μ L100:1 split   liner: 4 mm I.D., split, cup design   sample: 5 analytes , at concentrations indicated in 1 M Phosphoric acid suitability   application for GC Featured Industry   Food and Beverages Properties

48. LASER CUTTING & WELDING Linde technology is being used constantly the world over in laser applications – in manufacturing, metallurgy, chemicals, food processing , medicine, alternative fuel technologies & environmental technology . The LASERLINE® concept of high purity gas products and comprehensive services, applications know-how along with cost efficient gas supply options forms the basis for customised solutions that maximise productivity Leak Testing Producing tight systems is necessary, no matter if you produce tanks for the space shuttle, automotive gas tanks or gas distribution systems. Other typical leak test objects are air bags and pace makers, and anyone can understand what a disaster these could cause if not tight. Leak testing is often done with a gas or gas mixture together with a "sniffer" which is a specialized mass spectrometer (MS). Gas tanks and distribution systems are checked with helium or helium mixtures while automotive systems often are checked with sulphur hexafluoride

49. Gas chromatography mass spectrometry (GC/MS) is an important technique in the detection and identification of both bulk drugs and trace level drugs in biological samples. The PerkinElmer® Clarus® 600 GC/MS is a highly-sensitive and robust system with flexibility to accommodate the wide range of analyses typical to drug investigations. DRUGS-OF-ABUSE ANALYSIS BY GC/MS

50. RAPID ANALYSIS OF PESTICIDE RESIDUES IN GREEN BEANS: Pesticide analysis is extremely important due to the need to ensure that foodstuff is not contaminated with pesticide residues, which can be harmful to human health. Pesticide analysis poses a number of challenges for laboratories due to the wide ranging chemistries within the contaminants. Scientists have used gas chromatography-mass spectrometry (GC-MS) to obtain samples in order to construct an in-depth human glomerulus proteome database. They hope the database will help increase the understanding of renal disease pathogenesis, as well aiding biomarker exploration.

51. GAS CHROMATOGRAPHY-MASS SPECTROMETRY USED TO LOOK AT ALTERNATIVE INSECTICIDES FOR CONTROL OF MALARIA Gas chromatography-mass spectrometry has been used to look into the insecticidal activity of the essential oils in fruits and seeds taken from Schinus terebinth folia Raddiagainst Africa malaria and filarial vectors. Reported in the Parasites & Vectors journal, research assessed the plant oil against Anopheles  gambiae s.s, An.arabiensis and Culex quinquefasciatus . The twenty third instar larvae of the anopheles gambiaes.s  and Cx. quinquefasciatus were exposed to different dosages of the oil, with mortality rates being observed at 12, 24, 48 and 72 hours.

52. Barbiturates and benzodiazepines are usually encountered by the forensic scientist as tablet or capsule preparations that have been diverted from licit sources, or, particularly in the case of barbiturates, as ‘cutting agents’ in other drug materials (for example, phenobarbitone in heroin samples ). In some cases, identification and confirmation of the dose form can be achieved by using internationally available databases. If this is not possible, then the traditional process of physical description, presumptive testing, TLC and GC–MS should be followed to identify the drug components . However, some benzodiazepines are thermally labile and in such cases HPLC, possibly with diode-array detection, is often the chosen method of analysis . The latter technique is, in addition, the preferred method for quantification purposes. Such drugs, when obtained from licit sources, are very pure and it is therefore particularly difficult, if not impossible, to compare the samples in order to determine if they once originated from the same batch .

53. Novel method for a rapid measurement of the volatile compounds of food a fruit juice should not contain ethanol, but in some cases a fermentation can occur. The maximum ethanol concentration allowed is 0.5% vol. We were asked to propose a rapid method for the measurement of this ethanol content. The method was as follows: Apple juice (8ml) was placed in a 22ml vial and ethanol was added in order to obtain a concentration of between 0.05 and 0.5% vol. The sample was thermostatised at 30°C for 30min. The head-space was sampled using a SPME- fiber, with an adsorption time of 2 min . The desorption took place in the TV9000 in 1 min. The signal was measured with a FID. The Fig. 5 shows the correlation between the amount of ethanol added and the area of the signal, for both standard ethanol solutions and spiked samples . The high area before any addition of ethanol (0 concentration) comes from the volatile compounds of the apple juice. Using this method, we can determine the concentration of ethanol in apple juice, and also monitor the evolution of ethanol during the fermentation of apple juice. Conclusion The TV 9000 is... Simple........ Robust........ Easy to use ........

54. ANALYSIS OF ANABOLIC STEROIDS FOR DOPING CONTROL PURPOSES BY GC In this application note, the performance of both one dimensional GC-TOFMS and GC x GC-TOFMS were evaluated, with special attention to the detectability and the confirmation reliability at low ppb concentration. For this purpose, five anabolic steroids were selected, for which very low detection limits (2 ng/mL) are required by the World Anti-Doping Agency . QUALITATIVE COMPARISON OF WHISKY SAMPLES USING FAST GC In quality control of alcoholic beverages it is often important to compare different production batches to detect possible changes in the fermentation and/or distillation process. This note describes the application of a simple and fast GC method with MS detection using the Pegasus II Time of-Flight GC/MS detector . THE APPLICATION OF GC/MS TO THE ANALYSIS OF PESTICIDES IN FOODSTUFFS Pesticide contamination of foodstuffs has become a worldwide concern, prompting various levels of regulation and monitoring. The discovery of the structure of insulin, for example, was made possible when the British biochemist, Frederick Sanger, rationally and methodically applied the technique to the fragments of the ruptured insulin molecule, for which he received the 1958 Nobel prize for chemistry

55. Because of its simplicity, sensitivity, and effectiveness in separating components of mixtures, gas chromatography is one of the most important tools in chemistry. It is widely used for quantitative and qualitative analysis of mixtures, for the purification of compounds, and for the determination of such thermochemical constants as heats of solution and vaporization, vapour pressure and activity coefficients. Gas chromatography is also used to monitor industrial processes automatically: gas streams are analyzed periodically and manual or automatic responses are made to counteract undesirable variations. Many routine analyses are performed rapidly in environmental and other fields. For example, many countries have fixed monitor points to continuously measure the emission levels of for instance nitrogen dioxides, carbon dioxide and carbon monoxide. Gas chromatography is also useful in the analysis of pharmaceutical products, alcohol in blood, essential oils and food products. 

56. Gas chromatography is widely used for the separation and analysis of mixtures of many compounds at very low concentrations . The compounds which has low boiling points lower than 300 o C can be easily analyzed by this Technique . The main areas of application of gas chromatography are Analysis of toxic compounds, solvents, hydrocarbons as well as in forensic field, Pollution studies, environmental analysis. Gas chromatography is mainly used in Pharmaceutical industry for the quantitative as well as qualitative estimation of solid, liquid and gaseous organic compounds. This technique is preferred over spectrophotometry and titration because the separation. As well as (both qualitative and quantitative can be carried out simultaneously. 1.Qualitative analysis: Identification of the compound by GC either by following ways… Collecting the eluted vapours from the column and subjecting them to specific technique like Mass spectroscopy, I.R, U.V, NMR etc. The retention time here is used for qualitative analysis. Qualitative analysis That is to say what is that peak. The retention time is simply a the time from the point of injection to the peak Maximum. That is the characteristic of this column and this system these conditions .

57. If the sample under test and the standard compounds are same , then under identical conditions their resolution time are also same. Any deviation of graph from the standard Indicates the presence of a compound other than the standard . Specific Retention volume of sample The relative retention R (sample/standard) = Specific retention volume of standard 2. Quantitative analysis: The next imp factor is the peak area. The peak area is used for peak concentration. Twice the concentration twice the peak Area . This peak area represents the amount of sample which is present in the Peak . One can also use peak height. The world countries do not have computes often times simple rulers used for measuring peak heights. But In the modern world computers and integrates peak areas easily obtained and the results printed out on the recorders .

58. Pharmaceutical applications : Chromatography plays imp. Role in the analysis of pharmaceutical products and drugs . Quality control and analysis of drug products an d in monitoring metabolites in biological Fluids. Antibiotics Penicillin's and its derivatives, Gentamycin, kanamycin , Neomycin , tetracycline, chloramphenicol, etc. Anti T.B drugs Ethambutol, Isoniazid, Rifampicin. Anti cancer drugs 6- mercaptopurin, fluorouracil, doxorubin, tamoxifen, busulfan, thiotepa, melfalan, etc… Antivirals Amantadine, cytarabin, Idoxuridine CNS stimulants Caffeine, theophylline, Nikethamide General anesthetics Chloroform, ether ,ethanol etc. Sedatives/ hypnotics Barbiturates, Guanidine, Phenobarbital (luminol), Mephobarbital, Benzodiazepines, Tranquilizers( some Major and minor tranquilizers) Diazepam(Valium),Chlordiazepoxide (Librium), Flurazepam (Dalmane),Alprazolam(Xanax),Lorazepam (Ativan), phenothiazine, identified and measured by GC .etc. Tri cyclic Antidepressants and its metabolites.(TCA’s) Imipramine, Desipramine, Imitriptyline, Nor triptyline

59. Drug Solid phase Liquid phase Mobile phase Detector Atropine sulphate Acid washed salinized Diatomaceous support. 3% w/w of coated with phenyl methyl silicone Fluid . Nitrogen FID Homatropine Same as above Same as above Nitrogen FID Hyoscine hydrobromideeyeye drops. Same as above Same as above Nitrogen FID Clove oil same as above 3% w/w of PEG. Nitrogen FID Ethosuximide syrup Same as above 3%w/w of Cyanopropyl methyl phenyl, Silicone fluid. Nitrogen FID Steric acid Same as above 15% w/w of Diethylene Glycol Succinate polyester. Nitrogen FID

60. Ethyl oestrenol Glass column acid washed salinized diatomaceous support. Coated with 3%w/w phenyl methyl silicone fluid. Nitrogen FID Econazole nitrite cream same Coated with 3%w/w pf phenyl methyl silicane fluid glass column Nitrogen FID Chloroxylenol solution Same Coated with 3% PEG Nitrogen FID Fenfluramine Hcl tablets Same Coated with 10% PEG and 2% W/W of KOH. Nitrogen FID Lincomycin Hcl Same Coated with 3%W/W of phenyl methyl silicone fluid Helium FID Mianserin HCl Same Coated with 3% W/W Phenyl methyl silicone. Nitrogen FID Troxidone caps. Stainless steel column packed with porous polymer beads Nitrogen FID

61. 2. Isolation and identification of mixtures of plant extracts, carbohydrates, volatile oils, Amino acids, lipids proteins, preservatives, vitamins, colorants, flavours etc. 3. Identification and determination of fatty acids. Determination of fate of the drugs in body fluids like plasma, serum, urine. Etc. 4. Analysis of solvents, organic functional groups, natural fats ,alcoholic beverages etc. 5. Determination of protective coatings like styrene monomer, vinyl toluene, toluene diisocyanate etc. Miscellaneous Applications: Gas chromatography is widely used in the analysis of fertilizers, rubber, cosmetics, perfumes, food products and petroleum products. For detection of steroids taken by athletes during international sports competitions. IN environmental studies for the isolation and identification of chlorinated pesticides like DDT and BHC, organ mercuric compounds, organophorous compounds, Sulphur compounds etc. For the analysis of dairy products like milk, butter, cheese, etc., for the presence of aldehyde, ketones, milk sugars and fatty acids. Gas-liquid chromatography is applicable to species with high critical temperatures and normal boiling points as high as 400° C . Substances that are solids at normal laboratory conditions with molecular weights below 1,000 are best separated with liquid-solid or liquid-liquid systems . Lower members of the molecular weight scale range are amenable to supercritical-fluid separations. Size-exclusion methods are involved at molecular weights above 1,000. Field-flow fractionation extends the size range to colloids and microscopic particles.

62. GC Analysis of Ibuprofen Enantiomers( Underivatized ) on β-DEX ™ 120 application for GC Related Categories β-DEX 120 , Active Pharmaceutical Ingredients (APIs) , Analytical/Chromatography , Applications , Capillary GC Columns and Guard Columns/Retention Gaps , test parameters   column: Supelco β-DEX 120, 30 m x 0.25 mm I.D., 0.25 μm (24304)   gradient: 50 °C (5 min), 5 °C/min to 200 °C (10 min)   inj. temp.: 250 °C   detector: FID, 250 °C   carrier gas: helium, 60 m/sec., constant flow   injection: 1 μL , 100:1 split   sample: 2 mg/mL in methanol peak 1: S(+)-ibuprofen peak 2: R(-)-ibuprofen   liner: 4 mm I.D., FocusLiner ™ suitability   application for GC Featured Industry   Clinical Pharmaceutical (small molecule) active pharmaceutical ingredient

63. GC Analysis of Parabens on SLB ® -5ms after SPME using 50/30 μm DVB/Carboxen/PDMS Fiber application for GC, application for SPME Paraben is an preservative

64. Related Categories Analytical/Chromatography , Antimicrobials , Applications , Capillary GC Columns and Guard Columns/Retention Gaps , Capillary GC Columns, by industry / application , test parameters   sample/matrix: Paraben, each at 200 ppb in 3 mL water + 25% sodium chloride in a 4 mL vial   SPME fiber: metal fiber assembly coated with 50/30 μm DVB/ Carboxen /PDMS (57912-U)   extraction: immersion with stirring, 25 °C (15 min)   desorption process: 260 °C, 2 min   column: SLB-5ms, 20 m × 0.18 mm I.D., 0.36 μm (28576-U)   oven: 60 °C (2 min), 15 °C/min to 300 °C (5 min)   MSD interface: 275 °C   scan range: m/z 40-450   carrier gas: helium, 0.7 mL/min constant   liner: 0.75 mm I.D. SPME suitability   application for GC   application for SPME Featured Industry   Chemicals and Industrial Polymers Cosmetics, Personal Care, and Cleaning Products Food and Beverages Pharmaceutical (small molecule) Properties

65. GC Analysis of Class 1 Residual Solvents on OVI-G43 application for GC Related Categories Analytical/Chromatography , Applications , Capillary GC Columns and Guard Columns/Retention Gaps , Capillary GC Columns, by industry / application , Capillary GC Columns, by method reference , Capillary GC Columns, by name , Capillary GC Columns, by phase polarity , Chromatograms , Compound Class , GC Applications , GC Columns for the Pharmaceutical Industry , Gas Chromatography (GC) , Intermediate Polar Capillary GC Columns , OVI-G43 , Residual Solvents , Solvents , USP Less... test parameters   column: OVI-G43, 30 m x 0.53 mm I.D., 3.0 μm (25396) with 5 m intermediate polarity guard (25339) (25339)   oven: 35 °C (15 min), 5 °C/min to 200 °C   inj. temp.: 225 °C   detector: FID, 250 °C   carrier gas: helium, 30 cm/sec @ 35 °C   injection: 1 μL , 33:1 split   liner: single taper   sample: 5 analytes, at concentrations indicated in DMSO suitability   application for GC Featured Industry   Pharmaceutical (small molecule)

66. GC Analysis of Camphor Enantiomers on Astec ® CHIRALDEX ® G-DP application for GC Related Categories Active Pharmaceutical Ingredients (APIs) , Analytical/Chromatography , Applications , Astec CHIRALDEX G-DP , Capillary GC Columns and Guard Columns/Retention Gaps , Capillary GC Columns, by industry / application , Capillary GC Columns, by name , Chiral Capillary GC Columns , Chromatograms , Compound Class , Enantiomers , Flavors & Fragrances, Aroma , GC Applications , GC Columns for the Chemical Industry , GC Columns for the Flavor & Fragrance Industry , GC Columns for the Food & Beverage Industry , GC Columns for the Pharmaceutical Industry , Gas Chromatography (GC) , Ketones , Volatiles Less... test parameters   column: Astec CHIRALDEX G-DP, 30 m x 0.25 mm I.D., 0.12 μ m (78033AST)   oven: 100 °C   inj. temp.: 250 °C   detector: FID, 250 °C   carrier gas: helium, 30 psi   sample: peaks 1 & 2: camphor enantiomers suitability   application for GC Featured Industry   Chemicals and Industrial Polymers Flavors and Fragrances Food and Beverages Pharmaceutical (small molecule)

67. ADVANTAGES OF COMBINING GAS CHROMATOGRAPH AND MASS SPECTROGRAPH There are several advantages of putting the two devices together in one instrument. For one, it finishes the process faster. The accuracy of both processes is also not attained when they are done separately. This is because the sample to be taken into the mass spectrometer must be in its purest state. Once the process is done separately and the sample is taken out of the gas chromatograph, the sample will be tampered and the results will differ. Also, when they are done separately, there are instances that the separated elements in the gas chromatograph have similar ionized fragment pattern and can be misinterpreted by the mass spectrograph. At least with putting the two devices together in one instrument, the number of errors is reduced.

68. Bio fuel analysis EN 14110: GC Analysis of Methanol Impurity in Biodiesel on Equity ® -1 after SPME using 85 μm Polyacrylate Fiber application for GC, application for SPME Related Categories Alcohols , Analytical/Chromatography , Applications , Biodiesel: Methanol Impurity , Capillary GC Columns and Guard Columns/Retention Gaps , Capillary GC Columns, by industry / application , Capillary GC Columns, by method reference , Capillary GC Columns, by name , Capillary GC Columns, by phase polarity , Chromatograms , Compound Class , EN , Equity-1 , GC Applications , GC Columns for the Biofuel Industry , Gas Chromatography (GC) , Gases & Hydrocarbons , Non-Polar Capillary GC Columns , SPME Applications Less... test parameters   sample/matrix: 2 g of B100 biodiesel containing 0.01% methanol and 0.0785% 2-propanol in a 4 mL vial   SPME fiber: PK3 SPME ASSY 85UM POLYACRYLATE FS 24GA MAN (WHITE) (57304)   extraction: headspace, 60 °C for 5 min   desorption process: 250 °C for 0.75 min   column : Equity-1, 30 m x 0.32 mm I.D., 1.0 μm (28057-U)   oven: 50 °C   inj. temp.: 250 °C   detector: FID, 200 °C   carrier gas: helium, 30 cm/sec   liner: 0.75 mm I.D., SPME type, straight design (unpacked) suitability   application for GC   application for SPME Featured Industry   Biofuels Environmental

69. ENVIRONMENTAL CHECKING AND CLEANING Have you ever wondered how environmentalists said that our air is already polluted? How did they come up with such statement? How did they identify the elements that pollute our air? This is where gas chromatography-mass spectrometry comes in. Supposedly, the air we breathe should only be composed of O2. Through GC and mass spectrometry, the other elements that mixed with O2 that make the air polluted are separated and identified each. Through GC and mass spectrometry, the field of environmental studies has widened. GC Analysis of Solvents in Water on SPB ® -1 SULFUR after SPME using 75 μm Carboxen/PDMS Fiber application for GC, application for SPME

70. Related Categories Analytical/Chromatography , Applications , Beverage Analysis (Water) , Capillary GC Columns and Guard Columns/Retention Gaps , Capillary GC Columns, by industry / application test parameters   sample/matrix: solvents at 20 ppb in 4 mL water + 25% NaCl in 4 mL vial   SPME fiber: carboxen /PDMS, 75 μ m (57318)   extraction: immersion, 10 min, rapid stirring   desorption process: 270 °C, 5 min   column: SPB-1 SULFUR, 30 m × 0.32 mm I.D., 4.0 μm film (24158)   oven: 50°C (2 min) to 150°C at 10°C/min   inj. temp.: splitless (closed 2 min), 260°C, 0.75 mm I.D. liner   detector: FID   carrier gas: helium, 30 cm/sec suitability   application for GC   application for SPME Featured Industry   Chemicals and Industrial Polymers Environmental Forensics and Toxicology Properties:

71. CRIMINAL FORENSICS CSI and NCIS have become the most popular criminal forensic TV series of all times. Have you ever thought how they are able to solve crimes even without much physical evidences? GC and MS are responsible for this. When a person is killed with the use of chemical, the chemical as well as the criminal can be detected through this process. Even without the actual container of the chemical, it can still be detected through the blood sample of the victim. In arson cases, this is a technique used to solve the crime, specifically Pyrolysis Gas Chromatography. This is to identify the elements that caused the fire of the area.

72. DRUG IDENTIFICATION Specific drugs are prohibited on every state. In order to detect whether a person is taking the illegal drugs, GC and MS is applied. Drug test makes use of these processes. Through this, the examiners can identify what drugs have entered the body of the person through their urine, blood, and faeces sample . SECURITY PURPOSES Since the September 11, 2011 incident, US airports have made their security stricter. To execute this, all incoming and outgoing individuals of the United States have their baggage inspected through Thermo Detection. This process involves GCMS to detect whether the baggage contains explosives . ANALYSIS OF FOOD AND BEVERAGES FOR NUTRITION PURPOSES AND PERFUME One way to identify the nutrition value of a certain food or drink is through GCMS. Their elements are identified individually and are then analysed whether they should still be taken or not.

73. ENVIRONMENTAL MONITORING AND CLEAN UP GC-MS is becoming the tool of choice for tracking organic pollutants in the environment. The cost of GC-MS equipment has decreased significantly, and the reliability has increased at the same time, which has contributed to its increased adoption in environmental studies. There are some compounds for which GC-MS is not sufficiently sensitive, including certain pesticides and herbicides, but for most organic analysis of environmental samples, including many major classes of pesticides, it is very sensitive and effective. CRIMINAL FORENSICS GC-MS can analyse the particles from a human body in order to help link a criminal to a crime. The analysis of fire debris using GC-MS is well established, and there is even an established American Society for Testing Materials (ASTM) standard for fire debris analysis. GCMS/MS is especially useful here as samples often contain very complex matrices and results, used in court, need to be highly accurate.

74. GC-MS is increasingly used for detection of illegal narcotics, and may eventually supplant drug-sniffing dogs. It is also commonly used in forensic toxicology to find drugs and/or poisons in biological specimens of suspects, victims, or the deceased. SECURITY A post–September 11 development, explosive detection systems have become a part of all US airports. These systems run on a host of technologies, many of them based on GC-MS. There are only three manufacturers certified by the FAA to provide these systems,[citation needed] one of which is Thermo Detection (formerly Thermedics), which produces the EGIS, a GC-MS-based line of explosives detectors. The other two manufacturers are Barringer Technologies, now owned by Smith's Detection Systems, and Ion Track Instruments, part of General Electric Infrastructure Security Systems. FOOD, BEVERAGE AND PERFUME ANALYSIS Foods and beverages contain numerous aromatic compounds, some naturally present in the raw materials and some forming during processing. GC-MS is extensively used for the analysis of these compounds which include esters, fatty acids, alcohols, aldehydes, terpenes etc. It is also used to detect and measure contaminants from spoilage or adulteration which may be harmful and which is often controlled by governmental agencies, for example pesticides.

75. Gas chromatography–mass spectrometry (GC-MS) is a method that combines the features of gas-liquid chromatography and mass spectrometry to identify different substances within a test sample. Applications of GC-MS include drug detection, fire investigation, environmental analysis, explosives investigation, and identification of unknown samples. GC-MS can also be used in airport security to detect substances in luggage or on human beings. Additionally, it can identify trace elements in materials that were previously thought to have disintegrated beyond identification. GC-MS has been widely heralded as a "gold standard" for forensic substance identification because it is used to perform a specific test. A specific test positively identifies the actual presence of a particular substance in a given sample. A non-specific test merely indicates that a substance falls into a category of substances. Although a non-specific test could statistically suggest the identity of the substance, this could lead to false positive identification .

76. From war zones or scenes of natural disasters, news reporters often comment on the stench of decaying bodies. This characteristic malodour is made up of a complex mixture of volatile compounds that might be useful in forensic pathology, to establish the cause of death and the post-mortem interval. In the normal world, this characteristic smell is also well known to members of the police force, crime scene technicians, medical staff and forensic pathologists, as well as to some dogs. Its composition is the trigger used by tracker dogs to locate hidden bodies. The same odour is also recognised by insects that quickly colonise a body once it begins to decay. Now, Greek researchers have suggested that the odour can be used to determine the time since death and possibly help to establish the cause of death. First of all, they remind us that the VOCs that constitute the smell arise from the same sources in each human corpse. Carbohydrates in the body break down to give mainly oxygenated compounds (alcohols, aldehydes, ketones, acids, esters, ethers), proteins degrade to nitrogen, phosphorus and sulphur compounds, nucleic acids from nitrogen and phosphorus compounds and lipids decompose to nitrogen, phosphorus and oxygenated compounds and hydrocarbons. So, in theory, different decaying bodies should produce the same set of VOCs (volatile organic compounds) he adsorbed gases were analysed by thermal desorption GC/MS and the components were identified from their retention times and mass spectra using a commercial database and an in-house database constructed from standard compounds. The results were described in Forensic Sci. Intl. 2005. A total of 86 substances were identified and quantified with the aid of internal standard compounds. he relatively high levels of toluene were unexpected, leading the authors to hint at the possibility of toluene poisoning of the victims. The high number of fatty acid esters found was explained in terms of saponification. Many hydrocarbons, aldehydes, ketones and alcohols were also detected. GC AND THE SMELL OF DEATH(CORPSES )

77. Sniffer dogs can track the scent of human bodies