Inductively coupled plasma–atomic emission spectroscopy (ICP-AES) was used for the determination of lead using yttrium as an internal standard. A solution containing 2.45 ppm Pb2 and 4.87 ppm Y3 gave signals of 22 864 and 38 784 counts for lead and yttrium, respectively. A 0.2707g sample was dissolved in acid and quantitatively transferred to a 100.0-mL volumetric flask. A 1.00-mL aliquot of 200.0-ppm Y3 was added and the flask was diluted to volume with deionized water. ICP-AES analysis of the sample solution gave signals of 28609 and 16306 counts for lead and yttrium, respectively. What was the mass percentage of lead in the sample
