Mikasar The width of the chart shall be not less than mm. The relationship is independent of temperature, sample size, and carrier gas flow rate. The separation should be completed within 40 min, including reversal of flow after n-pentane to yield a group response for hexanes and heavier components. NOTE 1 — T h e sample size limitation of 0.

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NOTE 7-Most modem chromatographs have valve ovens that can be temperatur!? It is strongly recomeiJ. Two consecutive checks must agree within l. Daily calibrations are recommended. Zple-Samples must be equilibrated in the at "F above the source temperature of the field sampling: The higher the temperature the shorter the equilibration time approxi- mately two hours for small sample containers of mL or less. This analysis method assumes field sampling methods have removed.

If the hydrocarbon dewpoint of the sample is. Copper, vinyl, or rubber connections are not aqceptab! This small sample. Sufficient accuracy can be obtained for the deterlnination of all but the minor constit- uents by the use ofthis sample size. Avoid introduction of liquids into the sample system. The amount of purging required must be established and verified for each instru- ment.

The sample loop pressure shoJ. Ild be near atmospheric. Close the cylinder valve and allow the pressure of the sample in the loop or tube to stabilize. Then immediately inject the contents, of the loop or tube into the chromatographic column to avoid infiltration of contaminants. NOTE 8: Caution-Some components, such as carbon dioxide, hy- drogen sulfide, and hexanes and higher hydrocarbons, may be partially or completely removed by the water. Inject the sample into.

Select a sample size in accordance with 8. Enter the sample, and backflush heaVy components when appropriate. Obtain a corresponding response on the refer- ence standard.

The sample size must not exceed 0. Enter the samPle and obtain a re- sponse through methane Note 6. Likewise, obtain a re- sponse on the reference standard fot nitrogen and methane. ObtaiB a response on dry air for nitrogen and oxygen, if de- sired. The air must be either entered at an accurately meas- ured reduced pressure, or from a helium-diluted mixture. The percent nitrogen is multiplied by 0. Do not rely on oxygen standards that have been prepared for more than a few days. It is permissible to use a response factor for oxygen that is relative to a stable constituent.

Enter a 1 to 5-mL and record the response for helium, followed by hydrogen, which will be just ahead of oxygen Note 6. Obtain a corresponding response on a reference standard containing suitable concentrations of helium and hydrogen see Fig. Calculation 9. The expressed numerical value of any component in the sample shouldinot be presumed tq be.


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