SODIUMINPETROLEUMDISTILLATES BYFLAMEEMISSION,USINGANATOMIC ABSORPTIONSPECTROPHOTOMETER UOPMethod549-81 SCOPE This method is for determining sodium in petroleum distillate fractions, No. 2 fuel oil and lighter, over a concentrationrangeof o.o3ppmtoabout1wt-%.Sodiuminsamplesmayresult,forexample,from entrainment of aqueous droplets from a caustic washing operation or may be present as an oil-soluble salt. Analyses can be made for: (a) total sodium, which includes suspended alkali plus oil-soluble salts, and (b) oil-soluble sodium salts. The sodium content of the heavier distillates, whole crude, or residual oils should be determined by means of a wet-ashing technique, such as described in UOP Method 391. OUTLINEOFMETHOD Samples for the determination of total sodium (suspended aqueous alkali plus oil-soluble organosodium salts) are taken in specially cleaned bottles. The entire contents, including the suspended material, are extracted with dilute hydrochloric acid. Sodium is determined in the acid extract in the flame emission modeusing an atomicabsorption spectrophotometer (AAS). Samples for the determination of oil-soluble organosodium are filtered at the refinery process unit through glass wool which serves to coalesce the suspended aqueous alkali. The oil-soluble sodium in the filtered sample is determined by acid extraction in flame emission mode using an atomic absorption spectrophotometer. APPARATUS Atomicabsorptionspectrophotometer,singlebeam,withflameemissioncapabilitiesequippedwitha3- slot burner head, Perkin-Elmer Model 2280 with a PRS 10 printer sequencer, or equivalent Balance, capable of weighing to 0.1 mg Balance,platform, 1000-g capacity,capableofweighing to0.1g Beakers,disposable,polypropylene,30-mL.Sargent-Welch Scientific Co., Cat.No.S-4694-91,or equivalent IT IS THE USER'S RESPONSIBILITY TO ESTABLISH APPROPRIATE PRECAUTIONARY PRACTICES AND TO DETERMINE THE APPLICABILITY OF REGULATORY LIMITATIONS PRIOR TO USE. EFFECTIVE HEALTH AND SAFETY PRACTICES ARE TO BE FOLLOWED WHEN UTILIZING THIS PROCEDURE.FAILURE TO UTILIZE THIS THIS PROCEDURE SHOULD BE REVIEWED FOR SELECTION OF THE APPROPRIATE PERSONAL PROTECTION EQUIPMENT (PPE). C COPYRIGHT 1964, 1970, 1972, 1981 UOP LLC ALL RIGHTS RESERVED UOP Methods are available through ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken PA 19428-2959, United States. The Methods_may be obtained through the_ ASTM website, www.astm.org, or by contacting Customer Service at [email protected], 610.832.9555 FAX, or 610.832.9585 PHONE. 2 of 6 Bottle, glass, one-liter, fitted with molded screw caps containing a vinyl plastic liner, Sargent-Welch Scientific Co., Cat. No.S-8240-F, or equivalent Bottle, polypropylene, narrow mouth, with molded screw cap, one-liter capacity, Sargent-Welch Scientific Co., Cat.No. S-8420-40F, or equivalent Cylinder,graduated, 50-mL,Sargent-Welch Scientific Co., Cat.No.S-24665-D,or equivalent Flasks, volumetric, 50-,100-,500-and 1000-mL Funnel,12-cmdiameter,1-cm diameter stem Funnels, separatory with Teflon stopcock and polyethylene stopper, one- and two-liter, Fisher Scientific Co., Cat. No. 10-437-5E and 10-437-5F, or equivalent Pipet, volumetric transfer 5-, 10-, 25-, 40-, 50- and 100-mL Ring, support, iron with screw clamp, Sargent-Welch Scientific Co., Cat. No. S-73045-D, or equivalent Stirrer, magnetic, with Teflon-coated stirring bar REAGENTSANDMATERIALS All reagents shall conform to the specifications established by the Committee on Analytical Reagents of the American Chemical Society, when such specifications exist, unless otherwise specified.References to water mean deionized or distilled water, sodium-free. Acetone Air, compressed, dry,with a Matheson Regulator, Cat.No.8-590, or equivalent Glass wool, Pyrexbrand, Sargent-Welch Scientific Co.,Cat.No.S-40225, or equivalent Hydrochloric acid, concentrated (38%) Hydrochloric acid, 2-M.Dilute the concentrated acid with 6 volumes of water. Hydrogen, cylinder, prepurified, 99.95% with a M