Lead Limit Test Flame Atomic Absorption

Lead Determine as directed in the Flame Atomic Absorption Spectropho tome trie Method under Lead Limit Test, Appendix IIIB, using a 10-g sample. 

Standard Preparation On the day of use, dilute 3.0 mL of LeadNitrate Stock Solution (seethe Flame Atomic Absorption Method under Lead Limit Test, Appendix 11114) to 100 mL with water. Each milliliter of the Standard Preparation contains the equivalent of 3 pig of lead. 

Assay Dissolve about 500 mg of sample, accurately weighed, in 25 mL of 50% alcohol previously neutralized with 0.1 IV sodium hydroxide, add phenolphthalein TS, and titrate with 0.1 IV sodium hydroxide. Each milliliter of 0.1 A sodium hydroxide is equivalent to 12.21 mg of C7H602. Lead Determine as directed in the Flame Atomic Absorption Spectrophotometric Method under Lead Limit Test, Appendix IIIB, using a 10-g sample. 

Free Fatty Acids (as stearic acid) Transfer 2 g of sample, accurately weighed, into a dry, 125-mL Erlenmeyer flask containing 50 mL of acetone, fit an air-cooled reflux condenser onto the neck of the flask, boil the mixture on a steam bath for 10 min, and cool. Filter through two layers of Whatman No. 42, or equivalent, filter paper, and wash the flask, residue, and filter with 50 mL of acetone. Add phenolphthalein TS and 5 mL of water to the filtrate, and titrate with 0.1 A sodium hydroxide. Perform a blank determination (see General Provisions) using 100 mL of acetone and 5 mL of water, and make any necessary correction. Each milliliter of 0.1 A sodium hydroxide is equivalent to 28.45 mg of stearic acid (CigH gOi). Lead Determine as directed in the Flame Atomic Absorption Spectrophotometric Method under Lead Limit Test, Appendix NIB, using a 10-g sample. 

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