ASTM D4929 method for determination of organic chloride content in crude oil
DISTILLATION AND CLEANUP PROCEDURE
7. Apparatus
7.1 Round-Bottom Boiling Flask, borosilicate, 1 L, single short neck with 24/40 outer ground-glass joint.

7.2 Tee Adapter, borosilicate, 75° angle side-arm, 24/40 ground-glass joints.

7.3 Thermometer, ASTM thermometer 2C (-5 to 300°C) or 2F, (20°F to 580°F).

7.3.1 Other temperature measuring devices, such as thermocouples or resistance thermometers, may be used when the temperature reading obtained by these devices is determined to produce the same naphtha fraction that is obtained when mercury-in-glass thermometers are used.

7.4 Thermometer Adapter, borosilicate, 24/40 inner ground-glass joint.

7.5 Liebig Condenser, borosilicate, 300-mm length, 24/40 ground-glass joints.

7.6 Vacuum Take-Off Adapter, borosilicate, 105° angle bend, 24/40 ground-glass joints.

7.7 Receiving Cylinder, borosilicate, 250-mL capacity, 24/40 outer ground-glass joint.

7.8 Wire Clamps, for No. 24 ground-glass joints, stainless steel.

7.9 Receiver Flask, for ice bath, 4 L.

7.10 Copper Tubing, for heat exchanger to cool condenser water, 6.4-mm outside diameter, 3-m length.

7.11 Electric Heating Mantle, Glas-Col Series 0, 1-L size, 140-W upper heating element, 380-W lower heating element.

7.12 Variacs, 2, for temperature control of upper and lower heating elements, 120 V, 10 amps.

8. Reagents and Materials
8.1 Acetone, chloride-free. (Warning - Extremely flammable, can cause flash fires. Health hazard.)

8.2 Caustic Solution, 1 M potassium hydroxide (Warning - Can cause severe burns to skin.) prepared in distilled/deionized water.

8.3 Distilled/Deionized Water.

8.4 Filter Paper, Whatman No. 41 or equivalent.

8.5 Stopcock Grease.

8.6 Toluene, chloride-free. (Warning - Flammable. Health hazard.)

9. Sampling
9.1 Obtain a test unit in accordance with Practice D4057 or D4177. To preserve volatile components, which are in some samples, do not uncover samples any longer than necessary. Samples should be analyzed as soon as possible, after taking from bulk supplies, to prevent loss of organic chloride or contamination due to exposure or contact with sample container. (Warning - Samples that are collected at temperatures below room temperature may undergo expansion and rupture the container. For such samples, do not fill the container to the top; leave sufficient air space above the sample to allow room for expansion.)

9.2 If the test unit is not used immediately, then thoroughly mix in its container prior to taking a test specimen. Some test units can require heating to thoroughly homogenize. (Warning - When heating is required, care should be taken so that no organic chloride containing hydrocarbons are lost.)

10. Preparation of Apparatus
10.1 Clean all glassware by rinsing successively with toluene and acetone. After completing the rinse, dry the glassware using a stream of dry nitrogen gas. Obtain and record the masses of the round-bottom flask and receiving cylinder. Assemble the glass distillation apparatus using stopcock grease to seal all joints and wire clamps to prevent loosening of the joints. Adjust the thermometer position within the adapter tee such that the lower end of the capillary is level with the highest point on the bottom of the inner wall of the adapter tee section that connects to the condenser.

NOTE 1 - A diagram illustrating the appropriate positioning of the thermometer can be found in Test Method D86.

10.2 Form the copper tubing into a coil to fit inside the receiver flask, leaving room in the center of the flask for the receiving cylinder. With the PVC tubing, connect one end of the copper coil to the water source, and connect the other end of the coil to the lower fitting of the Liebig condenser cooling jacket. Connect the upper condenser fitting to the water drain. Fill the receiver flask with an ice/water mixture, and turn on the water. Maintain the temperature of the condenser below 10°C.

11. Procedure
11.1 Add a 500-mL crude oil test specimen to tared round bottom flask. Obtain and record the mass of the crude oil-filled flask to the nearest 0.1 g. Connect the flask to the distillation apparatus. Place the heating mantle around the flask, and support the heating mantle/flask from the bottom. Connect the heating mantle to the variacs. Turn on the variacs and start the distillation. During the distillation, adjust the variac settings to give a distillation rate of approximately 5 mL/min. Continue the distillation until a thermometer reading of 204°C (400°F) is attained. When the temperature reaches 204°C (400°F), end the distillation by first disconnecting and removing the receiving cylinder. After the receiving cylinder has been removed, turn off the variacs and remove the heating mantle from the flask. Obtain and record the mass of the receiving cylinder and distillate.

11.1.1 The precision and bias statements were determined using mercury-in-glass thermometers only. Therefore, when alternate temperature measuring devices are used, the cut-off temperature so obtained shall be that which will produce a naphtha cut similar to what would be yielded when mercury-in-glass thermometers are used. Such alternate temperature measuring devices shall not be expected to exhibit the same temperature lag characteristics as mercury-in-glass thermometers.

11.2 Transfer the naphtha fraction from the receiving cylinder to the separatory funnel. Using the separatory funnel, wash the naphtha fraction three times with equal volumes of the caustic solution (1 M KOH). Follow the caustic wash with a water wash, again washing three times with equal volumes. The caustic wash removes hydrogen sulfide, while the water wash removes traces of inorganic chlorides either originally present in the crude or from impurities in the caustic solution.

After the washings are complete, filter the naphtha fraction to remove residual freestanding water. Store the naphtha fraction in a clean glass bottle. This naphtha fraction can now be analyzed for organic chlorides by either sodium biphenyl or combustion/microcoulometric techniques.

11.3 Measure the density of the crude oil specimen and the naphtha fraction by obtaining the mass of 10.0 mL (using a 10-mL volumetric flask) of each to the nearest 0.1 g.

12. Calculation
12.1 Calculate naphtha fraction as follows:
f = Mn/Mc
where:
f = mass fraction of naphtha collected,
Mn = mass of naphtha collected, and
Mc = mass of crude oil specimen.

12.2 Calculate the density as follows:
Density, g/mL = m/v
where:
m = mass of sample specimen, g, and
v = volume of sample specimen, mL.