ASTM D500 Test Methods of Chemical Analysis of Sulfonated and Sulfated Oils
MOISTURE
Method A. Water by Distillation with Volatile Solvent
4. Scope
4.1 This test method covers the determination of water existing in a sample of sulfonated or sulfated oil, or both, by distilling the sample with a volatile solvent. The method is applicable only to sulfonated and sulfated oils that do not contain the following: mineral acids, free sulfonic acids, or free sulfuric acid esters; or alkali hydroxides, carbonates or acetates; or alcohol, glycerin, diethylene glycol, acetone, or other water-miscible volatile compounds.

5. Apparatus
5.1 The apparatus required consists of a glass flask heated by suitable means and provided with a reflux condenser discharging into a trap and connected to the flask. The connections between the trap and the condenser and flask shall be interchangeable ground joints. The trap serves to collect and measure the condensed water and to return the solvent to the flask. A suitable assembly of the apparatus is illustrated in Fig. 1.
5.1.1 Flask, 500-mL, of either the short-neck, round-bottom
type or the Erlenmeyer type.

5.1.2 Heat Source - The source of heat may be either an oil bath (stearic acid, paraffin wax, etc.), or an electric heater provided with a sliding rheostat or other means of heat control.

5.1.3 Condenser - A water-cooled glass reflux condenser (Fig. 1), having a jacket approximately 400 mm (15 3/4 in.) in length with an inner tube 9.5 to 12.7 mm (3/8 to 1/2 in.) in outside diameter. The end of the condenser to be inserted in the trap shall be ground off at an angle of 30° from the vertical axis of the condenser. When inserted into the trap, the tip of the condenser shall be about 7 mm (1/4 in.) above the surface of the liquid in the trap after the distillation conditions have been established. Fig. 1 shows a conventional sealed-in type of condenser, but any other condenser fulfilling the detailed requirements above may be used.

5.1.4 Trap - A trap made of well-annealed glass constructed in accordance with Fig. 1 and graduated as shown to contain 5 mL at 20°C. It shall be subdivided into 0.1-mL divisions, with each 1-mL line numbered (5 mL at top). The error in any indicated capacity may not be greater than 0.05 mL.

6. Reagents
6.1 Oleic Acid, heated previous to use for 5 to 10 min over a free flame at a temperature of 130 to 135°C.

6.2 Xylene.

7. Calibration
7.1 To calibrate the apparatus add approximately 1 g of water to a mixture of 80 g of xylene and 10 g of oleic acid. Conduct the distillation as described in 8.2-8.4. When all the water has distilled, cool the apparatus, add another g of water, and repeat the distillation. Continue the calibration up to the capacity of the receiving tube.

8. Procedure
8.1 Clean the condenser and the receiving tube thoroughly with soap and warm water before using. Rinse well, then treat with hot cleaning solution (a mixture of 10 mL of saturated potassium dichromate (K2Cr2O7) and 990 mL of sulfuric acid (H2SO4, sp gr 1.84)), and finally thoroughly wash and dry.

8.2 Take enough of the sample to be tested for analysis to yield about 4 mL of water. Introduce the approximate quantity into a weighing bottle and make the weighings from the bottle into the flask, taking care that after removal of the sample no drops of oil are left on the outside of the weighing bottle. Add 80 g of xylene and oleic acid equivalent to about two and one-half times the weight of the bone-dry sample to prevent foaming and jellying of the contents of the flask. Introduce glass beads to prevent bumping and mix the contents of the flask thoroughly by swirling, taking care to avoid any loss of material. Fill the trap with xylene and immediately connect the flask with the distillation apparatus. Insert a loose cotton plug in the top of the condenser tube to prevent condensation of atmospheric moisture in the condenser tube.

8.3 Heat the flask and regulate the heating so that the condenser tube immediately below the water jacket is just barely hot. In this way a minimum of water will condense farther up the condenser where it may be difficult to volatilize any moisture condensed on the walls.

8.4 Continue the distillation at the specified rate until practically no water is visible on any part of the apparatus except within the graduations of the trap. This operation usually requires less than 1 h. Increase the rate of distillation in order to remove all traces of condensed water in the condenser tube, and continue the distillation until the water level in the trap remains unchanged after a 10-min interval. Dislodge any droplets adhering to the side of the receiver with a thin copper wire twisted into a loop. Immerse the receiving tube in warm water at about 40°C for 15 min or until the xylene layer becomes clear, then read and record the temperature and the exact volume of the water in the trap.

9. Calibration
9.1 The volume of condensed water measured in the trap may be converted into its equivalent weight in grams by means of Table 1. Calculate the percentage of water as follows:
Water, % = (A/B) x 100
where:
A = weight of water, g, and
B = weight of sample, g.

Method B. Moisture and Volatile Matter by Hot-Plate Method
10. Scope
10.1 This test method covers the determination of the percentage of water and other compounds volatile at about 100°C existing in a sample of sulfonated or sulfated oil, or both, by rapid evaporation. The test method is applicable only to sulfonated and sulfated oils that do not contain the following: mineral acids, free sulfonic acids or free sulfuric acid esters, ammonia, acetic acid or similar volatile acids, alkali hydroxides, carbonates, acetates or similar salts that may react with oleic acid at elevated temperatures liberating volatile acids, or glycerin, diethylene glycol, xylene, or other compounds of similar volatility.

11. Apparatus
11.1 The apparatus required consists of a glass-stoppered weighing flask, a glass beaker, and a suitable thermometer.
11.1.1 Weighing Flasks - Any suitable glass-stoppered weighing flask of 10 to 15-mL capacity.

11.1.2 Beaker - A Griffin low-form glass beaker with an approximate capacity of 150 mL and a diameter of about 5 cm.

11.1.3 Heat Source - The source of heat may be either an electric hot plate with or without asbestos paper or board cover, or an open flame under a suitable asbestos board and a wire gauze (to spread the heat).

11.1.4 Thermometer, graduated from 90 to 150°C, about 3 in. in length, and substantially constructed.

12. Reagents
12.1 Desiccating Agent - Any suitable desiccating agent may be used.

NOTE 1 - Recent investigations seem to indicate that calcium chloride is unreliable as a laboratory desiccating agent.

12.2 Oleic Acid.

13. Procedure
13.1 Weigh approximately 5 g of oleic acid into the beaker and insert the thermometer. Heat the oleic acid gradually, while stirring with the thermometer, until the temperature reaches 130°C. Place the beaker in an oven at 105 to 110°C for 15 min, cool in a desiccator, and weigh. Repeat the heating over the hot plate and in the oven until two successive weighings differ by less than 1.5 mg.

13.2 Place about 6 g of the sample in the weighing flask and determine the weight accurately. Transfer the sample to the beaker (containing the oleic acid and the thermometer) and weigh the flask again. Heat the mixture exactly as in the taring of the beaker as described in 13.1. The loss in weight is equivalent to the moisture in the sample.

14. Calculation
14.1 Calculate the percentage of moisture and volatile matter in the sample as follows:
Moisture and volatile matter, % = (A/B) x 100
where:
A = loss of weight, g, and
B = weight of sample, g.