Coating fused-silica capillary columns

GC column silicone-coated fused silica capillary column, such as DB-5 or equivalent. 

Acetophenone can be analyzed by GC-FID, GC-PID, HPLC, or GC/MS. A silicone-coated fused-silica capillary column is suitable for GC/MS analysis. Characteristic ions for its identification are 105, 71, 51, and 120 (electron-impact ionization). Acetophenone in sohd wastes, soil, and sludges can be analyzed by GC/MS by EPA Method 8270 (U.S. EPA 1986). 

This procedure was used by Berezkin and coworkers for flexible fused silica columns [109]. The results of comparison of two squalane-coated fused silica capillary columns, one of which had previously been wall-coated with barium carbonate crystals, are given in Table 6-6 [109]. The capillary column with rough inner walls has better chromatographic characteristics. This result was confirmed by comparison of two chromatograms obtained on these columns (see Fig. 6-23 [106]). Only 7 chromatographic peaks were separated on the column with smooth walls while all 12 peaks were separated on the column with walls covered by barium car-... 

Early work relied on the use of packed columns, but all modern GC analyses are accomplished using capillary columns with their higher theoretical plate counts and resolution and improved sensitivity. Although a variety of analytical columns have been employed for the GC of triazine compounds, the columns most often used are fused-silica capillary columns coated with 5% phenyl-95% methylpolysiloxane. These nonpolar columns in conjunction with the appropriate temperature and pressure programming and pressure pulse spiking techniques provide excellent separation and sensitivity for the triazine compounds. Typically, columns of 30 m x 0.25-mm i.d. and 0.25-qm film thickness are used of which numerous versions are commercially available (e.g., DB-5, HP-5, SP-5, CP-Sil 8 CB, etc.). Of course, the column selected must be considered in conjunction with the overall design and goals of the particular study. 

Oxyfluorfen column, fused-silica capillary column coated with cross-linked methyl silicone (25 m x 0.3-mm i.d., 0.52- am film thickness) temperature, column 200 °C (1 min), 10°Cmin to 250 °C (5 min), inlet and detector 250 and 300 °C, respectively gas flow rates, N2 carrier gas 30mLmin , N2 makeup gas 30mLmin H2 3.5mLmin" air llOmLmin injection volume, 2 p.L. ... 

Fused-silica capillary column, 0.53-mm i.d., 30-m length coated with DB-WAX 170 °C 250 °C... 

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. 

Fused silica capillary columns of various internal bores and of lengths in the range 25 to 50 m are mainly employed for analytical separations. A variety of polar and non-polar column types are available including those open tubular types with simple wall coatings (WCOT), those with coatings dispersed on porous solid-supports to increase adsorbent surface area (SCOT) and porous layer open tubular (PLOT) columns. Important stationary phases include polyethylene glycol, dimethylpolysiloxane and different siloxane copolymers. Various sample introduction procedures are employed including ... 

Gas chromatography of the soil extract was carried out on a Varian 3700 instrument equipped with a flame ionization detector and a fused silica capillary column (25in, 0.25mm i.d.) coated with CP-SIL 5. Samples were injected spitlessly, and nitrogen was used as a carrier gas. The oven temperature was programmed from 40°C (5min) to 300°C at 5°C/min. 

Column Fused-silica capillary column size (50 M x 0.32 mm) coated with a 5-pm film of chemically-bonded polymethyl siloxane ... 

Samples of both fulvic and humic acids were suspended in methanol and methylated with diazomethane. Both H and spectra of the free acids were obtained, at 299.94 MHz and 75.42 MHz respectively, on a Varian XL-300 spectrometer having a Nicolet TT-100 PET accessory. Spectra were obtained in D2O, in a 12-mm tube, with deuterated TSP (sodium 3-(trimethylsilyl)propionate-, , 3,3- 4) added as internal reference. GC/MS of methylated acids was conducted on a Hewlett-Packard Model No 5995 GC/MS/DA system equipped with a fused silica capillary column (12 m x. 020 mm ID, Hewlett Packard) internally coated with crosslinked methylene silicone. Infrared spectra were obtained with solid samples dispersed in KBr pellets, by using a Beckman IR-33 spectrophotometer. The various absorption peaks in IR and NMR were interpreted conventionally (9-10). 

Chirasil-Val, which is commercially available in both enantiomeric forms143, is stable up to 240 C when coated on carefully pretreated glass or fused silica capillary columns. The best performance is obtained when the chiral side chains in Chirasil-Val are separated by an average of five dimethylsiloxane units144. Using a Chirasil-Val column, the simultaneous enantiomer separation of all proteinogenic amino acids is possible (Figure 11). 

More polar cyclodextrin derivatives (Table 2), coated on fused silica capillary columns, have also been applied 177 - 180. 

Many types of cyclodextrin derivatives coated onto fused silica capillary columns are commercially available, notably, permethyl-/3-cyclodextrin dissolved in OV-1701 (CP-Cyclodextrin-/l-2,3,6-M-19) and Chirasil-Dex from Chrompack International14,3 and Lipodex A-D (Table 2) from Macherey-Nagel182. 

Capillary gas chromatography (GC) using modified cyclodextrins as chiral stationary phases is the preferred method for the separation of volatile enantiomers. Fused-silica capillary columns coated with several alkyl or aryl a-cyclo-dextrin, -cyclodextrin and y-cyclodextrin derivatives are suitable to separate most of the volatile chiral compounds. Multidimensional GC (MDGC)-mass spectrometry (MS) allows the separation of essential oil components on an achiral normal phase column and through heart-cutting techniques, the separated components are led to a chiral column for enantiomeric separation. The mass detector ensures the correct identification of the separated components [73]. Preparative chiral GC is suitable for the isolation of enantiomers [5, 73]. 

The GC was calibrated using a mixture of known quantities of d-limonene, d-limonene oxide (cis and trans), 2-octanone, and carvone. GC analyses were performed by injecting 1 pi samples with 1 40 split (column flow split flow), into a Hewlett-Packard 5840A GC equipped with a flame ionization detector. A fused silica capillary column 50m x 0.25 mm i.d., coated with OV-101 as a liquid phase was used. Column temperature was programmed from 50-250 C at 10 C/min, and helium was used as the carrier gas. 

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. 

One can find 1-mm glass-lined stainless steel columns or fused silica capillary columns. Fused silica is available with 75-yU.m, 100-/xm, or 320-/xm internal diameter by 20-cm, 25-cm, or 30-cm length. Fused silica is a glass tubing with an outside polyimide coating to prevent breakage. 

GC Analysis. GC analyses were performed on a Hewlett-Packard 5880 gas chromatograph equipped with a 60 m x 0.25 mm I.D. fused silica capillary column coated with a 0.25 ym film of SE-52. From an initial value of 40°C, the column temperature was programmed at... 

GC-MS Analysis. GC-MS analyses were performed on a Hewlett Packard 5985 GC-MS instrument in the electron-impact (70-eV) mode. The gas chromatograph on the 5985 instrument was equipped with a 60 m x 0.25 mm I.D. fused silica capillary column coated with 0.25 pm of SE-54 the column was programmed from 40°C to 300°C at 5°C/min, where it was maintained isothermally for 8 min. A splitless injection system was used to introduce the sample onto the GC-MS instrument. A mass range of 50 to 400 amu was scanned every 1.0 sec by computer (HP-2100MX equipped with the HP-7920 Large Disc Drive). 

Conventional high pressure NICI spectra were obtained using a Hewlett-Packard 5985B quadrupole GC/MS, as described previously (1). Methane was used as the Cl reagent gas and was maintained in the source at 0.2-0.4 torr as measured through the direct inlet with a thermocouple gauge. A 200 eV electron beam was used to ionize the Cl gas, and the entire source was maintained at a temperature of 200° C. Samples were introduced into the spectrometer via the gas chromatograph which was equipped with a 25 meter fused silica capillary column directly interfaced with the ion source. For all experiments, a column coated with bonded 5% methyl phenyl silicon stationary phase, (Quadrex, Inc.) was used and helium was employed as the carrier gas at a head pressure of 20 lbs. Molecular sieve/silica gel traps were used to remove water and impurities from the carrier gas. 

J. Kramer, R. Fouchard, et al., Difference in chromatographic properties of fused silica capillary columns, coated, crosslinked, bonded or crosslinked and bonded with polyethylene glycols (Carbowas 20 M) using complex fatty acid methyl ester mixtures, J. Chromatogr. Sci., 23 54-56 (1985). 

A stereoselective GC method for determination of etodolac enantiomers in human plasma and urine was first reported as a preliminary method [35], and then as a validated method [36]. Sample preparation involved addition of (S)-(+)-naproxen (internal standard) and sodium hydroxide to diluted plasma or urine. The samples were washed with diethyl ether, acidified with hydrochloric acid, and extracted with toluene. ( )-(+)-naproxen was used as a derivatizing agent to form diastereomeric derivatives of etodolac. The gas chromatograph system used in this work was equipped with fused-silica capillary column (12 m x 0.2 mm i.d.) coated with high-performance cross-linked methylsilicone film (thickness 0.33 pm) and a nitrogen-phosphorous detector. The operating conditions were injector 250°C detector 300°C column 100-260°C (32 °C/min). 

The effect of temperature on retention was studies using n-hexadecane on a 20 m, 50ji I.D. fused silica capillary column coated with an OV-17 phase using FID detection. The OV-17 was cross-linked in-situ to decrease its solubility in the supercritical fluid. The stationary phase film thickness was calculated to be 0.25pm. The... 

A 50 meter, 0.31 mm fused silica capillary column coated with 0.52 micron film thickness of SE-54 (Hewlett-Packard Ultra 2, 5% phenylmethyl silicone) was used for the separations with detection via flame ionization (FID) and flame photometric (FPD Hewlett-Packard Model 19256A). Injections were performed manually with the injection port at 200 C, splitter ratio 8 1, and 1 pi sample injected with temperature programming from 50 C (5 minute hold) at a 5 C/minute ramp to 180 °C (10 minute hold). Carrier gas flow was 2.5 ml/min at 40 °C and gas regulation on the FPD was hydrogen, 70 ml/min, and air, 80 ml/min for operation (310 ml/min total for ignition). 

Procedure (See Chromatography, Appendix IIA.) Use a gas chromatograph capable of split and splitless capillary column injection and equipped with a flame ionization detector and a 25-m x 0.53-mm (id) fused-silica capillary column coated with a 2.0-p.m film of 5% phenyl/95% methylsilicone liquid phase, or equivalent, and a 30-m x 0.32-mm (id) fused-silica capillary column, or equivalent, coated with 1.8-p.m film of (6% cyanopropylphenyl) methylpolysiloxane liquid phase, or equivalent, connected in series, with the first column that was described placed behind the second. Set the injector temperature to 150°, the detector to 250°, and the oven to 40° isothermal. Use helium as the carrier gas at a flow rate of 4.4 mL/min. Set the split flow at a rate of 98 mL/min. 

Procedure Inject 1-pL aliquots of the Standard Preparation and the Sample Preparation into a gas chromatograph equipped with a split injector, a flame-ionization detector, and a 25 -m fused silica capillary column coated with a 2-pm film of 7% cyanopropyl-7% phenyl-85% methyl-1% vinylpolysiloxane (CP-Sil 19 CB, Chrompack Middelburg, or equivalent). Maintain the column at 100°, raising the temperature at 8°/min to a final temperature of 300°. Set the injector temperature to 270°and the detector temperature to 270°. Use a mixture of helium and methane, at a split ratio of 1 100, as the carrier gas, flowing at 120 mL/ min. Run the chromatogram for 27 min. 

Gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) analyses GC analyses are performed on a WCOT (wall-coated open tubular) polydimethylsiloxane fused silica capillary column (1 fim film thickness, 50m x 0 32mm ID ) Shorter columns for example 25m, or columns with thinner films, for example 0 2/im, may also be used successfully Injection of the silylated sample (2/d) is performed with a moving needle-type injector, other types of capillary GC injection systems may be used after optimization of the concentration and amount of sample to be injected With a 50-m capillary... 

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