Use of isotachophoresis as a reference method for the simultaneous determination of barium and strontium

When using X-ray fluorescence spectrometry for the determination of alkali and alkaline earth metals in a silica matrix, frequent recalibration with reference samples is necessary. Determination of metals in these reference samples is carried out using classical analysis. The latter was not possible with barium and strontium in the presence of each other owing to mutual interference. Isotachophoresis, using a 0.02 mol/1 potassium—citrate leading electrolyte of pH 5.0 and magnesium chloride as a terminator proved suitable. At concentration ratios in the range 1:10 to 10:1 the accuracy and precision were well within the 1% requirement