A 5.00-mL sample of blood was treated with trichloroacidic acid to precipitate proteins. After centrifugation, the resulting solution was brought to a pH of 3 and was extracted with two 5.00-mL portions of methyl isobutyl ketone containing the organic lead complexing agent APCD. The extract was aspirated directly into an air-acetylene flame yielding an absorbance of 0.577 at 283.3 nm. A five-milliliter aliquot of an aqueous standard solution containing 0.213 g/mL Pb was treated in the same way and yielded absorbance of 0.357. Calculate the concentration Pb (in g/mL) in the sample assuming that Beers law is followed.