Methane sample chromatogram

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. 

With natural gas being a mixture of such structurally simple compounds, options available for correlation purposes are limited. Gas chromatography provides an indication of the distribution of the components present in the namral gas sample from which the ratio of methane/C2+ fraction can be determined. This is measure of the wetness of the gas and in certain cases can provide a measure of the maturity of the gas. The ratio needs to be combined with carbon and isotope ratio data to obtain the most useful information. A gas can be dominated by methane and, from the chromatogram alone, it is impossible to determine whether this is biogenic gas or a high maturity gas. As a result of thousands of... 

The fundamental criteria for assessing a column s capabilities relate to its separating capabilities in terms of the retention characteristics, column efficiency and the stationary phase at OPGV, and temperature cycle. Retention characteristics of a component are indicated by its retention ratio, k (k = t f /tM)- Dead time, is an indication of the OPGV and is readily determined by introducing a sample of methane onto the column. Column efficiency, N or Veir, can be calculated using data from the chromatogram... 

Separation of permanent gases on a molecular sieve column is shown in Fig. 2-2a [21]. Separation of oxygen, nitrogen, methane and carbon monoxide on a 3.6 m X 3 mm column at 70 °C is complete in less than 20 min. Fig. 2-2b [21] shows the same separation completed in 2.5 min using a wide-bore ALOT fused-silica column at 25°C. This chromatogram was obtained on a 10 m x 0.53 mm column with 50 n.m layer of molecular sieve 5A using direct sample injection and a carrier gas flow rate... 

Variations from 350 °C to 490 "C in pyrolysis temperature produced no change in the area of the acetic acid peak, but did cause area variation in the methane peak. The pyrolysis chromatogram of poly(ethylene-ethyl acrylate) at 475 "C shows one principal peak due to ethanol. No variation in peak areas was noted in the temperature range 300 °C to 480 °C. Table 3.6 shows the analysis of 0.05 g samples of poly(ethylene-ethyl acrylate (PEEA) and poly (ethylene-vinyl acrylate) (PEVA) obtained at a pyrolysis temperature of 475 °C. 

Barrall and co-workers [66] have described a pyrolysis - gas chromatographic procedure for the analysis of polyethylene - ethyl acrylate and polyethylene - vinyl acetate copolymers and their physical mixtures. They used a specially constructed pyrolysis chamber as described by Porter and co-workers [67]. Less than 30 seconds is required for the sample chamber to assume block temperature. This system has the advantages of speed of sample introduction, controlled pyrolysis temperature and complete exclusion of air from the pyrolysis chamber. The pyrolysis chromatogram of polyethylene - vinyl acetate contains two principal peaks due to methane and acetic acid ... 

A1.2.2 Enter a 1 to 5-mL sample into the partition column and reverse the carrier gas flow after -pentane is separated. Obtain a corresponding chromatogram of the reference standard. Measure the peak heights of ethane through /i-pentane and the areas of the pentane peaks of the standard. Make calculations on ethane and heavier components in the same manner as for the complete analysis method. Methane and lighter may be expressed as the difference between 100... 

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