Sources of error in determining lead in blood by atomic absorption spectrophotometry.

203Pb was used to monitor sample-preparation techniques used in four atomic absorption methods for determination of lead in blood. Sources of error and their magnitude were identified and measured for each of the following analytical procedures: precipitation with trichloroacetic acid, separation with ammonium pyrrolidine dithiocarbonate into methyl isobutyl ketone, digestion with acids, and coprecipitation with bismuth and direct analysis after a “nonextraction” procedure. The determination of lead in blood supplemented with inorganic lead was compared with that of naturally bound lead obtained from experimentally poisoned animals. Because of differences in in vivo and in vitro lead binding, recovery of added inorganic lead may not accurately reflect the fate of endogenous lead in some analytical procedures.