Temperature programming WCOT

Figure 3. Components trapped from the air over cut potato leaves. Carbon traps were extracted with 60 fxL of CSt IftL was used for CC (detector FID). GC conditions WCOT Carbowax 20M column, 50 m long temperature programmed 70-150 °C. Key a, trans-2-hexenal b, cis-3-hexenyl acetate c, cis-3-hexen-l-ol and d, tians-2-hexen-l-ol (14).

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... 

Sample extracts were analysed by capillary gas chromatography with electron capture detection using either Perkin-Elmer series 8310 or 8510 instruments. One microlitre aliquots were injected via a split/splitless injection system operated in the splitless mode. The components were separated on a 25 m WCOT fused silica capillary column (CP-Sil-5, internal diameter 0.22 pm, Chrompack, UK). The stationary phase was non-polar 100% dimethylpolysiloxane. The temperature program for the separation of chlorobenzenes was based upon the work of Lee et al (1986). Quantification was based on the method of internal or external standard. 

A small volume TCD still requires a reference flow to be well matched with the sample flow. For most wide bore WCOT columns, make-up gas is required to obtain the available resolution of the system For SCOT columns this can be neglected without serious loss In efficiency. Regulation and balancing of the reference and sample flows are relatively easy when only Isothermal operation is employed, but become very difficult when temperature programming is necessary. 

Figure 5.1 (c) On (i) polar and (ii) non-polar capillary WCOT columns illustrating like attracts like polar/non-polar retention properties and two column analysis to confirm components present. Toluene is used as the reference marker. 1, Methyl alcohol 2, ethyl alcohol 3, isopropyl alcohol 4, n-propyl alcohol 5, wo-butyl alcohol 6, iec-butyl alcohol 7, rert-butyl alcohol 8, n-butyl alcohol 9, toluene (reference marker). Polar column Carbowax 20M (25m X 0.32, 0.25 pm film). Non-polar column HP-1, dimethylsiloxane (25m x 0.32, 0.25 pm film). Both columns carrier gas He 1ml min injection 0.5 pi split 20 1 detector FID column temperature programmed 50-200°C at 5°C min. ... 

Figure 5.8 Column bleed, 25 m x 0.25 mm WCOT column dimethylsiloxane stationary phase, temperature programmed 50-350°C at 20°C min . ...

Samples (1 pi) of standards 1 and 2 and the soil extract were injected onto a 25 m WCOT BP5 capillary column temperature programmed 50-260°C at 15°C min , helium flow-rate 1 ml min , ECD, autoinjector with a precision of better than 99.4% (Table 10.16). 

Figure 5.13. Separation (part chromatogram) of very-long-chain fatty acids (methyl esters) from the cholesterol ester fraction of brain lipids from patients with Zellweger syndrome [838]. A fused silica WCOT column (12 m x 0.22 mm) coated with a methylsilicone phase (BP-1 ) was temperature-programmed from 160 to 320 C, with helium at 1 mL min as the carrier gas. (Reproduced by kind permission of the authors and of the Biochemical Journai, and redrawn from the original paper).

Figure 8.2. Separation of interesterified palm oil on a glass WCOT oolumn (6 m x 0.4 mm) coated with a methylsilioone phase [616], Helium at 6 mL/min was the carrier gas, and the oven was temperature-programmed from 250 to 350°C at 4°C/min. The numbers above eaoh peak refer to the carbon number of the oomponent. (Reproduced by kind permission of the authors and of Revue Francaise des Corps Gras, and redrawn from the original paper).

Figure 8.17. High-temperature GC of derivatized plasma lipids on a WCOT column (8 m x 0.3 mm) of fused silica, coated with SE-54, and temperature-programmed to a maximum of 340 C [647]. Abbreviations A, TMS ester derivatives of free acids B, TMS ethers of monoacylglycerols (derived from lysophosphatidylcholine) C, TMS ether of cholesterol D, tridecanoin (internal standard) E, TMS ether of 16 0-sphingosine (derived from sphingomyelin) F, TMS ethers of diacylglycerols (derived from phosphatidylcholine) and ceramides G, more TMS ethers of ceramides H, cholesterol esters J, triacylglycerols. (Reproduced by kind permission of the authors and of the Journal of Biochemical and Biophysical Methods, and redrawn from the original paper).

Fig. 5.3 Chromatograms of urinary acidic metabolites extracted using DEAE-Sephadex and separated as their ethoxime and trimethylsilyl derivatives on OV-101 by temperature programming on a packed column (upper) and WCOT capillary column (lower). Selected peaks are identified for comparative purposes. These are 1, lactic 2, glycollic 3, oxalic 4, sulphate 5, phosphate 6, succinic 7, 4-deoxyerythronic 8, 4-deoxythreonic 9,3-deoxytetronic 10,2-deoxytetronic 11, erythronic 12, threonic 13, 3-hydroxy-3-methylglutaric 14, citric 15, uric 16, n-tetracosane (standard) 17, n-hexacosane (standard) (Tracey and Chalmers, unpublished).

Fig. 11.2 Total ion current chromatogram (Varian MAT 44 GC-MS) of organic acids extracted using ethyl acetate and diethyl ether from the urine of a patient with propionic acidaemia and separated as their trimethylsilyl derivatives on a 25 m SE-54 WCOT capillary column using temperature programming from 70°C to 220°C at 4 C min Peak identifications are 1, lactate 2, 3-hydroxypropionate 3, 3-hydroxybutyrate 4, 2-methyl-3-hydroxybutyrate 5, 3-hydroxyisovalerate 6, 3-hydroxy- -valerate 7, aceto-acetate 8 and 9, 2-methyl-3-hydroxyvalerate 10, 3-oxovalerate 11, 2-methyl-3-oxo-valerate (isomer 1) 12,2-methylacetoacetate 13,2-methyl-3-oxovalerate (isomer 2) 14 propionylglycine 15, glutarate 16, adipate 17, 5-hydroxymethyl-2-furoate 18, 2-hydroxyglutarate 19,3-hydroxy-3-methylglutarate 20,4-hydroxyphenylacetate 21 and 22, methylcitrate 23,4-hydroxyphenyl-lactate 24, palmitate. (Redrawn with modifications from Truscott et al., 1979)...

Standards with a poor UV chromophore (4-methyl-2-pentanone, 1-chlorododecane, and stearic acid) were analyzed on a Perkin-Elmer 3920 gas chromatograph with a flame ionization detector and a 30-m SE-54 wall-coated open tubular (WCOT) fused-silica capillary column (J W Scientific). The injector temperature was 200 °C the detector interface temperature was 280 °C. The carrier gas was He at 16.5 lb/in.2, and the makeup gas was nitrogen at a flow of 40 cm3/min. Splitless l-/zL injections of the 25,000 1 concentrates were made by starting with an oven temperature of 45 °C and the oven door open after 2.75 min, the oven door was closed and the temperature was programmed at 4 °C/min to 280 °C, which was held for 8 min. The syringe was kept in the injection port for 15 s after injection. 

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