Temperature programmed column fractionation

Figure 12.7 Cliromatograms of a polycarbonate sample (a) microcolumn SEC ti ace (b) capillary GC ti ace of inti oduced fractions. SEC conditions fused-silica (30 cm X 250 mm i.d.) packed with PL-GEL (50 A pore size, 5 mm particle diameter) eluent, THE at aElow rate of 2.0ml/min injection size, 200 NL UV detection at 254 nm x represents the polymer additive fraction ti ansfeired to EC system (ca. 6 p-L). GC conditions DB-1 column (15m X 0.25 mm i.d., 0.25 pm film thickness) deactivated fused-silica uncoated inlet (5 m X 0.32 mm i.d.) temperature program, 100 °C for 8 min, rising to 350 °C at a rate of 12°C/min flame ionization detection. Peak identification is as follows 1, 2,4-rert-butylphenol 2, nonylphenol isomers 3, di(4-tert-butylphenyl) carbonate 4, Tinuvin 329 5, solvent impurity 6, Ii gaphos 168 (oxidized). Reprinted with permission from Ref. (14).

Figure 12.22 SFC-GC analysis of aromatic fraction of a gasoline fuel, (a) SFC trace (b) GC ttace of the aromatic cut. SFC conditions four columns (4.6 mm i.d.) in series (silica, silver-loaded silica, cation-exchange silica, amino-silica) 50 °C 2850 psi CO2 mobile phase at 2.5 niL/min FID detection. GC conditions methyl silicone column (50 m X 0.2 mm i.d.) injector split ratio, 80 1 injector temperature, 250 °C earner gas helium temperature programmed, — 50 °C (8 min) to 320 °C at a rate of 5 °C/min FID detection. Reprinted from Journal of Liquid Chromatography, 5, P. A. Peaden and M. L. Lee, Supercritical fluid chromatography methods and principles , pp. 179-221, 1987, by courtesy of Marcel Dekker Inc.

Figure 8.19 Two-diaenslonal separation of the components of a coal derived gasoline fraction using live switching. Column A was 121 n open tubular column coated with poly(ethelene glycol) and column B a 64 m poly(dimethylsiloxane) thick film column. Both columns were temperature programmed independently taking advantage of the two oven configuration. Peak identification 1 acetone, 2 2-butanone, 3 > benzene, 4 isopropylmethylketone, 5 isoprop-anol, 6 ethanol, 7 toluene, 8 => propionitrile, 9 acetonitrile, 10 isobutanol, 11 — 1-propanol, and 12 = 1-butanol. (Reproduced with permission from Siemens AG).

Boylan and Tripp [76] determined hydrocarbons in seawater extracts of crude oil and crude oil fractions. Samples of polluted seawater and the aqueous phases of simulated samples (prepared by agitation of oil-kerosene mixtures and unpolluted seawater to various degrees) were extracted with pentane. Each extract was subjected to gas chromatography on a column (8 ft x 0.06 in) packed with 0.2% of Apiezon L on glass beads (80-100 mesh) and temperatures programmed from 60 °C to 220 °C at 4°C per minute. The components were identified by means of ultraviolet and mass spectra. Polar aromatic compounds in the samples were extracted with methanol-dichlorome-thane (1 3). 

GC and GC-MS Analyses. Glass capillary columns were prepared in our laboratories as described briefly elsewhere (3). Aliquots (l-2 ul) of the PAH fraction dissolved in a small volume of chloroform were injected without stream splitting into the Hewlett Packard 5dk0A gas chromatograph. Injection port temperature was held at 250°C, and the column oven temperature was started at 100°C. Two minutes after injection a multistep temperature program was initiated final temperature was 290°C. Nitrogen was the carrier and make up gas. 

Figure 4. Total ion gas chromatogram of GPC fraction 3 of S02-solubles (Figure 2). Columns 5% Dexsil 300 on 100/120 Chromosorb H-WP, 1/8 in o.d. X 8 ft, carrier gas 20 mL helium/min, temperature program 80°-270° C at 2°/min for 40 min followed by 4°/min. See Table 1 for peak identification.

Figure 6. Gas chromatograms of volatiles isolated from pH 9 NLIB top chromatogram, neutral fraction bottom chromatogram, basic fraction 60 m x 0.32 mm fused silica DB-1 column, temperature programmed 50°C for 0.1 min., then 4 C/mln. to 230-C, held at 230 C for 10 min.

PLAC fractions (Fr II 2, Scheme 1) were analyzed by temperature-programmed GC with fused silica capillary columns coated with SE-54 (HP5 0.2 mm inner diameter, 0.11 cm film thickness or U2 0.2 mm inner diameter, 0.33 pm film thickness). Length of the columns was 25 or 50 m. 13C-labeled PCDD/Fs added before extraction and after cleanup were used as internal standards for quantitative results and recovery, respectively. Mass selective detector (HP 5970) or magnetic sector mass spectrometer (mostly VG AutoSpec) was used for electron impact LRMS or HRMS, respectively. Mass spectral data of the analyzed substance groups are collected in Table 3. Exact quantification was achieved only in a few cases when authentic standard compound was available. In most... 

Figure 4, Gas chromatogram of nonpolar fraction of TOSCO 11 (Green River) shale oil on a 100 X, 03 in. i,d. FFAP PLOT column. Substrate Chromosorb R6470-1 temperature program 40°-225°C at 4" C/min,...

Figure 11. Capillary GLC of the hydrocarbon fraction of olive oil (blend of refined and virgin olive oil). Column DBS, 25 m x 0.25 mm i.d., 0.2- im film thickness split ratio 1 15 temperature program 233 C, 6 min 2(y C/min 28S C final temperature injector 30O C detector 320" C, 1, cholesta-3,5-diene (internal standard) 2, stigmasta-3,5-diene.

In such a system, the pre-column acts as a real g.c. column for which the temperature can be independently programmed. A fraction of the g.c. effluent from this column can be cold trapped in the inlet of a second column, of the analytical type, most often a capillary one with high separation power. 

Each fraction was evaporated to dryness in 10-ml pear-shaped flasks, redissolved in a small amount of methylene chloride, and gas chromatographed. GC conditions were as follows column, 6 ft X 0.125 in. od stainless steel packed with 3% OV-17 on 100-120 mesh Gas-Chrom Q temperature program, 70-330°C at 12°/min, holding at the flnal temperature for up to 20 min and carrier gas flow rate, 28 ml/min. Fractions containing very little material or with GC patterns very much like adjoining fractions were combined. These fractions were then analyzed on the GC-MS computer system to obtain mass spectral data on the individual components. For certain fractions additional information was gained from ultraviolet spectra. 

The nonacidic fractions were analyzed using a coupled GC-MS system. The system consisted of a Hewlett-Packard 5840A gas chromatograph and a Hewlett-Packard 5985 mass spectrometer. A J W fused silica capillary column (30m x 0.25mm)coated with DB-1 (methyl silicon) was used for the analysis. The column was held for 2 min at 40°C and then temperature programmed to 250°C at 4°C/min. Mass spectra were obtained at 70eV and a source temperature of 200°C. 

Gas chromatographic analysis was performed with each fraction using a Varian Vista 6000 gas chromatography (GC) system coupled with a Vista 401 data system (Varian Instruments, Sunnyvale, CA). A flame ionization detector (FID) was used and the sample was separated on a glass capillary column (30 m x 0.25 mm with WCOT SE-30), temperature programmed from 100 C to 280 C at 8°/min, and held at 280 C for 10 min, which allowed observation of the n-alkane... 

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