Combination of chemical modifiers and graphite tube pre-treatment to determine boron by electrothermal atomic absorption spectrometry

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Abstract
Several ways of increasing the atomization efficiency in the determination of B by electrothermal atomic absorption spectrometry were evaluated: the use of a chemical modifier (Ni, Pd and ascorbic acid); pretreatment of the graphite tubes with carbide forming elements (Zr, Ta and V); and addition of NaF as a cleaning solution between measurements. The tubes were pre-treated by soaking in the carbide forming metal solution under vacuum, drying for 4 h at 150 °C and finally subjecting them to slow electrothermal heating to at least 1600 °C in order to form the metal carbide on the inner side of the tube. The best results were obtained using Zr-treated tubes in conjunction with Ni as chemical modifier. This resulted in high sensitivity (80 pg), a negligible memory effect and an increased tube lifetime (200 atomization cycles of 3 s at 2650 °C). The method was successfully applied to determine B in waste and river waters.