Liquid chromatography flame-ionization detectors

Gas chromatography-flame ionization detector Gas chromatography/liquid chromatography-mass spectrometry... 

Several experimental techniques can be used to study transport phenomena in polymers nuclear magnetic resonance imagiug (NMR), UV spectrophotometer, gas chromatography/flame ionization detector (GCMD), high-performance liquid chromatography (HPLC), laser interferometry, gravimetric method and Fourier Transform Infra-Red spectroscopy (FTIR). 

Despite their importance, gas chromatography and liquid chromatography cannot be used to separate and analyze all types of samples. Gas chromatography, particularly when using capillary columns, provides for rapid separations with excellent resolution. Its application, however, is limited to volatile analytes or those analytes that can be made volatile by a suitable derivatization. Liquid chromatography can be used to separate a wider array of solutes however, the most commonly used detectors (UV, fluorescence, and electrochemical) do not respond as universally as the flame ionization detector commonly used in gas chromatography. 

For selective estimation of phenols pollution of environment such chromatographic methods as gas chromatography with flame-ionization detector (ISO method 8165) and high performance liquid chromatography with UV-detector (EPA method 625) is recommended. For determination of phenol, cresols, chlorophenols in environmental samples application of HPLC with amperometric detector is perspective. Phenols and chlorophenols can be easy oxidized and determined with high sensitivity on carbon-glass electrode. 

Epichlorhydrin (ECH) detection starts with detecting epoxide cycle using hydrochloric acid in combination with sodium chloride the reaction product - 1,3-dichlorhydrin - is extracted in diethyl ether and concentrated by removing the latter. Gas-liquid chromatography with a flame-ionization detector is used to detect glycerin 1,3-dichlorhydrin. The sensitivity of the method is 0.01 mg/dm. ... 

One example of normal-phase liquid chromatography coupled to gas chromatography is the determination of alkylated, oxygenated and nitrated polycyclic aromatic compounds (PACs) in urban air particulate extracts (97). Since such extracts are very complex, LC-GC is the best possible separation technique. A quartz microfibre filter retains the particulate material and supercritical fluid extraction (SPE) with CO2 and a toluene modifier extracts the organic components from the dust particles. The final extract is then dissolved in -hexane and analysed by NPLC. The transfer at 100 p.1 min of different fractions to the GC system by an on-column interface enabled many PACs to be detected by an ion-trap detector. A flame ionization detector (PID) and a 350 p.1 loop interface was used to quantify the identified compounds. The experimental conditions employed are shown in Table 13.2. 

The purity of 1 and 2 is assessed by analytical gas-liquid chromatography (GC) on a Hewlett-Packard 5890 gas chromatograph equipped with a flame-ionization detector and fitted with a 50 m x 0.2 mm HP-5 fused silica glass capillary column using linear temperature programming from an initial temperature of 150°C for 5 min to a final temperature of 200°C for 10 min at a rate of 5°C/min. 

The cracking of diphenylmethane (DPM) was carried out in a continuous-flow tubular reactor. The liquid feed contained 29.5 wt.% of DPM (Fluka, >99%), 70% of n-dodecane (Aldrich, >99% solvent) and 0.5% of benzothiophene (Aldrich, 95% source of H2S, to keep the catalyst sulfided during the reaction). The temperature was 673 K and the total pressure 50 bar. The liquid feed flow rate was 16.5 ml.h and the H2 flow rate 24 l.h (STP). The catalytic bed consisted of 1.0 g of catalyst diluted with enough carborundum (Prolabo, 0.34 mm) to reach a final volume of 4 cm. The effluent of the reactor was condensed at high pressure. Liquid samples were taken at regular intervals and analyzed by gas chromatography, using an Intersmat IGC 120 FL, equipped with a flame ionization detector and a capillary column (Alltech CP-Sil-SCB). 

Hewlett-Packard Model 6890 equipped with a nitrogen-phosphorus flame ionization detector Capillary column for gas-liquid chromatography (GLC), DB-1, 0.53-mm i.d. x 15 m, l-pm film thickness (J W Scientific)... 

The extracted fractions were esterified with either BF3-MeOH reagent or diazomethane and analyzed by GLC. Gas liquid chromatography (GLC) was conducted with a Perkin-Elmer Sigma 3 equipped with flame ionization detector. Separations were obtained on a Hewlett Packard 12 m x 0.2 mm i.d. capillary column coated with methyl silicon fluid (OV-101). The temperature was maintained at 80°C for 2 min then programmed from 80 to 220°C at 8°C/min. The injector temperature was 250°C. Mass spectra were obtained on a Hewlett Packard model 5995 GC-MS mass spectrometer, equipped with a 15 m fused silica capillary column coated with 5% phenyl methyl silicone fluid. Spectra were obtained for major peaks in the sample and compared with a library of spectra of authentic compounds. 

ECD = electrochemical detection FID = flame ionization detector GC = gas chromatography HPLC = high performance liquid chromatography M = molar NaOH = sodium hydroxide NR = not reported rpm = revolutions per minute... 

Some detection procedures involve the loss of the sample for example, in the flame ionization detectors used in gas chromatography the sample is burnt, while in liquid chromatography the addition of a colour reagent will also result in the loss of the sample. For such methods to be used in a preparative... 

High-performance liquid chromatographic separation with electrochemical detection may provide the best sensitivity for phenol quantification in biological samples. The use of gas chromatography with a flame ionization detector may be a more versatile method, if other non-ionic pollutants must be quantified. The advantages and disadvantages of different methods available for the quantification of phenol and metabolites in biological and environmental samples have been discussed by Tesarova and Packova(1983). 

ECO = electron capture detector ED = electrochemical detector FID st flame ionization detector GC = gas chromatography HECD = Hall s electrolytic conductivity detector HPLC = high performance liquid chromatography MEC = molecular emission cavity analysis MS - mass spectrometry HD = photo-ionization detector... 

Figure 1.6 ICH Class 2 solvents measured using GC. Purification of pravastatin sodium by preparative liquid chromatography. Reprinted from [15], copyright 2004, with permission from Elsevier. (Column 30 m X 0.53 mm i.d. 3 pm OVI-G43 (Supelco) carrier gas helium at 5 ml/min injection in split mode total flow 25 ml/min injector temperature 140 C flame ionization detector temperature 25C C and oven temperature 40°C for 20 min, to 240°C at 10°C/min, maintain at 240 C for 20 min. The components are 1 methanol, 3 acetonitrile, 4 dichloromethane, 5 hexane, 6 cw-l,2-dichloroeth-ylene, 7 nitromethane, 8 chloroform, 9 cyclohexane, 13 1,2-dimethoxyethane, 15 1,1,2-trichloroethyl-ene, 16 methylcyclohexane, 17 1,4-dioxane, 18 pyridine, 19 toluene, 20 2-hexanone, 21 chlorobenzene, 22 ethylbenzene, 23 m-xylene, 24p-xylene, 25 o-xylene, and 26 tetralin. The solvents are dissolved in DMF and heated at 80X for 60 min, and a sample of the headspace is injected.)...

GC = gas chromatography FID = flame ionization detector HPLC = high performance liquid chromatography HRGC high resolution gas chromatography MS = mass spectrometry RSD = relative standard deviation UV = ultraviolet light... 

The amount of cresol in the concentrated extract can then be determined by high performance liquid chromatography (HPLC) (DeRosa et al. 1987 Yoshikawa et al. 1986) or gas chromatography (GC) coupled to either a flame ionization detector (FID) or a mass spectrometer detection system (Angerer 1985 Needham et al. 1984). Separation of the cresol isomers by gas chromatography is readily accomplished, and the use of an appropriate internal standard allows the determination of their concentrations. Although exact detection limits were not given for the above GC methods, a concentration of 10 ppm appears to be readily determined. 

Toluene disproportionation was carried out in a high-pressure continuous flow micro reactor. Granular catalyst (32-64 mesh, 2.5 cm ) was loaded into a stainless steel tube reactor. Toluene was fed at a rate of 10 cm h (liquid) in the flow of H2S(0.2vol.%)/H2 mixture gas (200 cm min b at 623K and 6MPa. The effluent was analyzed by gas chromatography (Shimadzu, GC-9A) by a flame ionization detector (FID). 

Conversion to acetates, trifluoroacetates (178), butyl boronates (179) trimethylsilyl derivatives, or cyclic acetals offers a means both for identifying individual compounds and for separating mixtures of polyols, chiefly by gas—liquid chromatography (glc). Thus, sorbitol in bakery products is converted to the hexaacetate, separated, and determined by glc using a flame ionization detector (180) aqueous solutions of sorbitol and mannitol are similady separated and determined (181). Sorbitol may be identified by formation of its monobenzyhdene derivative (182) and mannitol by conversion to its hexaacetate (183). 

EC = electron capture detection FID = flame ionization detector GC = gas chromatography hexa = hexabrominated biphenyl HRGC = high resolution gas chromatography HRMS= high resolution mass spectrometry LC = liquid chromatography MS = mass spectrometry NCI = negative chemical ionization RED = plasma emission detection PBBs = polybrominated biphenyls... 

Fig. 30 Silver ion high-performance liquid chromatography (Ag-HPLC-FID) with flame ionization detector (FID) analysis of the triacylglycerols of chromatographed Crepis alpina seed oil. Ag-HPLC-FID conditions 0.5-mg sample 5-micron Chromspher Lipids column (Chrompack International, Middelburg, The Netherlands) (4.6 X 250 mm) mobile phase 0.5% acetonitrile in hexane (v/v) flow rate 1.0 ml/min FID. Chromatogram peak triacylglycerol fatty acid abbreviations S, saturated (palmitic and stearic) O, oleic L, linoleic and Cr, crepenynoic fatty acids.

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