Ascorbic acid as a matrix modifier for determination of tin in concentrated boric acid solutions by electrothermal atomic-absorption spectrometry

It has been found that the atomic-absorption signal for tin is reduced in the presence of 5 μ1 of 0.05–0.30 M boric acid at STPF-conditions. It has been proposed that the reason for the boron interferences is the formation of SnB(g) at the atomization stage. In the presence of palladium chloride the interferences from 0.2 M boric acid are reduced by a factor of 1.3. The interferences are reduced most effectively when the sample is atomized from a polycrystalline graphite platform or in the presence of ascorbic acid. The interference of up to 0.2 M boric acid can be suppressed and the area of the tin signal doubled. It is proposed that the observed phenomenon is connected with the bonding of boron as non-volatile B 4C. Ascorbic acid is the most effective matrix modifier for the determination of different trace elements in boron compounds.