ASTM D4424 Standard Test Method for Butylene Analysis by Gas Chromatography
8. Procedure
8.1 If a vapor sample is to be injected using a gas sample valve, a representative portion of the liquid butylenes must be taken and vaporized into a suitable container. As a suggestion, a small, 5 or 10 mL aliquot of liquid butylenes under pressure in a valved, 5 or 10-mL sample cylinder can be expanded into a larger container as a vapor. Then this resultant vapor would be injected into the chromatograph.
8.2 If a liquid sampling valve is used, pressure the sample cylinder to at least 1100 kPa (160 psig) with either helium or nitrogen.
8.3 Take the sample after the proper preparation has been done and inject it into the gas chromatographic column using the appropriate sampling valve. Record the chromatogram using as low an attenuation as possible to insure all peaks are on scale and as large as possible.
8.4 Measure the peak areas after all peaks have eluted. Measurement may be automatic by using either mechanical or electronic integrators or computers.
9. Calculations
9.1 Calculate the concentration ofeach component using the following equation:
Ci = (Ai x Fi x 100/∑Ai x Fi)
where:
Ci = concentration of the i-th component,
Ai = peak area of the i-th component,
Fi = calibration factor for the i-th component, and
∑Ai x Fi = sum of all products of peak areas times calibration factors.
