Ammonium fluoride as a novel chemical modifier for the elimination of magnesium chloride interference on the determination of lead by graphite furnace atomic absorption spectrometry

Ammonium fluoride was found to be very efficient modifier for the elimination of MgCl₂ interference on Pb determination. Ammonium fluoride probably converts strongly interfering volatile MgCl₂ to less volatile MgF₂ matrix that makes possible the release of Pb analyte at lower temperature, before the matrix starts to vaporize. It was observed likewise that NH₄F removes the interferences mentioned, i.e. caused by MgCl₂ presence, much more effectively as compared with some modifiers, before now recommended for this purpose. The application of this modifier to the determination of Pb in 2% (m/v) MgCl₂ has ensured the characteristic mass and LOD value in the original sample of 12 pg and 60 ng g⁻¹, respectively (10 μl aliquots of sample). Applying the modifier to standards and samples enables the use of matrix-free standard solutions for attaining accurate analysis as verified by recovery studies.