6. Reagents and Materials
6.1 Purity of Reagents - Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents conform to the specifications of the Committee on Analytical Reagents 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.
6.2 Purity of Water - Unless otherwise indicated, references to water shall be understood to mean reagent water as defined by Type II of Specification D 1193.
6.3 The synthetic sea water shall have the following composition:
6.3.1 The solution can be conveniently prepared as follows. This procedure avoids any precipitation in concentrated solutions with subsequent uncertainty of complete resolution. Using certified pure (cp) chemicals and distilled water, prepare the following stock solutions:
6.3.2 To prepare the synthetic sea water, dissolve 245.4 g of NaCl and 40.94 g of Na2SO4 in a few litres of distilled water, add 200 mL of Stock Solution No. 1 and 100 mL of Stock Solution No. 2 and dilute to 10 L. Stir the 10-L batch and add 0.1 N Na2CO3 solution until the pH is between 7.8 and 8.2. One or two millilitres of the carbonate solution will be required.
6.4 Precipitation Naphtha, as specified in Test Method D 91. (Warning - Flammable. Health hazard.)
6.5 Isooctane, as specified in Motor Fuels, Section I, Annex A2, Table 32, Reference Materials and Blending Accessories. (Warning - Flammable. Health hazard.)
6.6 IP 60/80 Petroleum Spirit, as specified by IP Standard Reference Liquids, Appendix B. (Warning - Flammable. Health hazard.)
6.7 Steel Test Rod, as specified in Section 8.
7. Sampling
7.1 Sample for this test can come from tanks, drums, small containers, or even operating equipment, and they should be truly representative of the entire quantity. Therefore, use the applicable apparatus and techniques described in Practice D 4057, or other comparable standard practice.