Calculation of lead concentration from K-series X-ray fluorescent studies uses a robust normalization technique based on the amplitude or area of the elastic signal. Parameter estimation of the elastic signal can be affected by the overlap of the K β 2 line, especially for concentrations greater than 40ppm where the K β 2 amplitude can be greater than 1% of the elastic signal. We tested the combination of estimation by method of least moduli and doublet deconvolution. We found that the estimation of the area of the elastic signal is more robust to changes in the low-energy end of the region of interest with the combined method than with method of least-squares estimation and singlet processing. We recommend use of the combined method for creation of calibration curves at concentrations greater than or equal to 40ppm.