Graphite tubes with small internal diameters tailored for high-resolution continuum source graphite furnace atomic absorption spectrometry

Abstract

Graphite tubes with internal diameters of 1 mm, 1.5 mm and 2 mm (mini tubes) were developed and adapted for use in high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS). The applicability and analytical performance of the mini tubes were tested. Use of a 2 mm tube resulted in no loss of lamp radiation when compared to the use of a 5.8 mm standard tube, while the use of 1.5 mm and 1 mm tubes resulted in about 20% and 70% loss of lamp radiation, respectively. One to several microlitres of liquid samples were introduced to the tube through an end hole using a conventional autosampler. Due to the smaller atomizer volume, analytical sensitivity was significantly improved. For 51 of the 62 elements tested, the improvement in sensitivity of a 2 mm tube over a 5.8 mm tube met or exceeded the values expected (factors 6 to 12). The feasibility of the mini tube concept for sample analysis was demonstrated by the determination of elements in model and real sample solutions under the influence of inorganic and organic matrices, yielding reliable results in all cases. The mini tubes provide high absolute sensitivity and can be used for ultra-trace analysis of small samples.