Analytical determinations. other than gravimetric

According to Hllllbrand and Lundell (H3) the best of the volumetric methods for lead Is precipitation of lead chromate from acetic acid solution, dissolution of the washed precipitate In hydrochloric acid, addition of excess potassium Iodide and titration of the liberated Iodine with a standard sodium thiosulfate solution. This procedure has recently been reviewed by Ryazanov (R2). 

Due to the tendency of lead to form stable complexes with many organic molecules a number of volumetric procedures 

Direct complexlmetrlc tltratron of lead with 0.07 N complexon III in.the presence of Erichrome Black T as an. indicator has been proposed (Zl). The equivalence point is reached when the color changes from violet to bluegreen. 

The most sensitive - and perhaps for the radiochemist, the most useful volumetric procedure is complexlmetrlc titration utilizing the lead EDTA complex. A number of Indicators have been used for the direct EDTA titration (W5) The most popular of these are Erlochrome Black T (Cl) (W5)j Eriochrome Red B and X-ylenol orange (W5)- The direct titration with the sodium salt of EDTA is carried out in a pH 10 buffer solution (P5)(p6). Iron, the alkaline earths and the earths interfere but bismuth, aluminum and antimony do not. Cyanide can be used to mask cobalt, nickel, copper, zinc, cadmium, mercury and platinum (Cl), 

The volumetric methods of determination have been little used by the radiochemist and wlli probably remain so. Certain special conditions may warrant their use so they have been reviewed briefly. 

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