ASTM D3230 standard test method for salts in crude oil (Electrometric Method)
6. Apparatus
6.1 The apparatus (see Annex A1) shall consist of a control unit capable of producing and displaying several voltage levels for applying stress to a set of electrodes suspended in a test beaker containing a test solution. The apparatus shall be capable of measuring and displaying the current (mA) conducted through the test solution between the electrodes at each voltage level.
NOTE 1 - Some apparatus are capable of measuring voltage and current internally and, after comparison to internal calibration curves, of displaying the resultant concentration.
6.2 Test Beaker - See Annex A1.
6.3 Pipet, 10 mL (total delivery) - The type of pipet that is rinsed to ensure the entire volume of the material is contained in the intended volume.
6.4 Cylinders, 100 mL, stoppered.
6.5 Other volumetric and graduated pipets and volumetric flasks.
7. Reagents and Materials
7.1 Purity of Reagents - Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the American Chemical Society, where such specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination.
7.2 Purity of Water - Unless otherwise indicated, references to water shall be understood to mean reagent water as defined by Type II in Specification D1193.
7.3 Mixed Alcohol Solvent - Mix 63 volumes of 1-butanol and 37 volumes of absolute methyl alcohol (anhydrous). To each litre of this mixture, add 3 mL of water. (Warning - Flammable. Liquid causes eye burns. Vapor harmful. May be fatal or cause blindness if swallowed or inhaled.)
NOTE 2 - The mixed alcohol solvent is suitable for use if its conductivity is less than 0.25 mA at 125 V ac. High conductivity can be due to excess water in the solvent and can indicate that the methyl alcohol used is not anhydrous.
7.4 Hexanes, Reagent Grade, (Warning - Extremely flammable, harmful if inhaled.)
NOTE 3 - Hexanes solvent is sometimes referred to or sold by other names, such as petroleum naphtha, petroleum ether, ligroine, petroleum benzin, and industrial naphtha. One should confirm that it meets the requirements of 7.4.
7.5 Calcium Chloride (CaCl2) Solution (10 g/L) - Transfer 1.00 more or less 0.01 g of CaCl2, or the equivalent weight of a hydrated salt, into a 100-mL volumetric flask and dissolve in 25 mL of water. Dilute to the mark with mixed alcohol solvent.
7.6 Magnesium Chloride (MgCl2) Solution (10 g/L) - Transfer 1.00 more or less 0.01 g of MgCl2, or the equivalent weight of a hydrated salt, into 100-mL volumetric flask and dissolve in 25 mL of water. Dilute to the mark with mixed alcohol solvent.
7.7 Sodium Chloride (NaCl) Solution (10 g/L) - Transfer 1.00 more or less 0.01 g of NaCl into a 100-mL volumetric flask and dissolve in 25 mL of water. Dilute to the mark with mixed alcohol solvent.
7.8 Oil, Refined Neutral - Any refined chloride-free oil of approximately 20 mm2/sec (cSt) viscosity at 40°C and free of additive.
7.9 Salts, Mixed Solution (Concentrated Solution) - Combine 10.0 mL of the CaCl2 solution, 20.0 mL of the MgCl2 solution, and 70.0 mL of the NaCl solution, and mix thoroughly.
NOTE 4 - The 10:20:70 proportions are representative of the chlorides present in a number of common crude oils. When the relative proportions of calcium, magnesium, and sodium chlorides are known for a given crude oil, such proportions should be used for most the accurate results.
7.10 Salts, Mixed Solution (Dilute Solution) - Transfer 10 mL of the concentrated mixed chlorides solution into a 1000-mL volumetric flask, and dilute to the mark with mixed alcohol solvent.
7.11 Xylene, reagent grade, minimum purity. (Warning - Flammable. Vapor harmful.)
