Spectra of SDSS J1114+1828 and SDSS J1143+2020 in the region of the Pb line. The synthetic spectra have been computed without Pb (green line) and with A(Pb)= 1.5 and 2.1 (thin blue lines). The best fits (thick red line) are obtained with A(Pb)= 1.6 for SDSS J1114+1828 and A(Pb)= 1.8 for SDSS J1143+2020. The dots at the bottom of the figures represent the difference between the best fit and the observed spectrum (shifted upward by 0.7).