ASTM D4864 Test Method for Determination of Traces of Methanol in Propylene Concentrates by Gas Chromatography
12. Procedure
12.1 Weigh the sampling cylinder containing at least 100 g of propylene concentrate to the nearest 0.1 g.
NOTE 7 - When practical, it is advisable to weigh the sampling cylinder before sampling to obtain a tare mass.
12.2 Pressure deionized water into the injection device in a vertical position from the bottom and close the valves.
12.3 As shown in Fig. 3, connect the injection device to the sample cylinder using a hex coupling or other suitable device.
12.4 Attach the other end to an inert gas source at 1724 kPa (250 psig) and purge the lines between V2 and V5.
12.5 Close V5 and tighten the connection at V2.
12.6 Pressure the water into the cylinder by opening Valves V1, V2, V3, and V4, in that order.
12.7 Close valves V1 and V4 and depressure the device via V5. Then disconnect the cylinder.
12.8 Remove any residual water from the outlet of V4 and reweigh the cylinder to 0.1 g. The difference between this mass and that in 12.1 is the mass of the water, W.
12.9 Shake the cylinder vigorously for at least 10 min.
12.10 Clamp the cylinder in a vertical position and allow the aqueous phase to settle. (When the cylinder contains an outage tube, it must be at the top of the cylinder.)
12.11 Carefully open the bottom valve and drain the aqueous phase containing the methanol into an appropriate container (vial or flask) and cap it. (Warning - As soon as the aqueous phase drains, high-pressure liquified propylene concentrate will surge out.)
12.12 With the GC at the proper operating conditions, inject the appropriate size of the aqueous extract for the GC and calibration being used.
12.13 Safely vent off the remaining propylene in the sample cylinder and reweigh it to 0.1 g (unless the cylinder was already tared.) The difference between this mass and that in 12.1 is the mass of the propylene concentrate extracted, G.
