Determination of the distribution coefficient of Pb in NaCl crystals by estimation of the lead concentration from the optical absorption in aqueous solutions

It is shown that the intensity of a UV absorption band of lead ions in aqueous solution of NaCl is linear dependent on the concentration of lead. This can be developed to a simple determination method of lead in NaCl crystals even in the ppm region. Its application on melt grown NaCl:PbCl₂ crystals was used for a calculation of the distribution coefficient, for which was found k = 0.24. Furthermore it could be shown that an essential part of lead is evaporated from the melt before the growth process starts so that the real initial concentrations are drastically lower than the nominal concentrations of the melts.