“…The conjugate of BSA protein with Pb-DTPA (Pb-DTPA-BSA) was prepared by a modification of the method previously reported. 22 Briefly, a solution of p -SCN-Bn-CHX-A′′-DTPA (3 mM, in 0.1 M sodium phosphate buffer, pH 9.5) was prepared. Aliquot (1 mL) of p -SCN-Bn-CHX-A′′-DTPA solution was mixed with an equal volume of lead nitrate solution (3 mM, in 50 mM phosphate buffer, pH 9.5).…”