Comparison of pyrolytic graphite tubes from two commercial firms used for the determination of antimony in sediment acid extracts

Two commercial firms of pyrolytic graphite-coated tubes with L'vov platform were compared when applied to determine Sb in sediment acid extracts. Five chemical modifiers were assayed using each firm and it was found that HNO3 , performed best, avoiding several problems encountered when the other modi fiers were tried. Both firms showed similar results but one of them exhibit ed improved atomic signals and better separations between the atomic and ba ckground signals. It was also studied that the effect of tube ageing should be taken into account and, so, establish control schemes. Additionally, th e use of peak height as the analytical signal doubled the sensitivity obtai ned regarding that achieved with integrated absorbances. However, the forme r was significantly affected by the ageing of the tube making impossible di rect quantitation using aqueous standards.