Direct analysis of coffee and tea for aluminium determination by electrothermal atomic absorption spectrometry

A method for direct analysis of tea and coffee samples by using electrother mal atomic absorption spectrometry is described. Coffee and tea from differ ent sources were analyzed without digestion step. For slurry analyses the s amples were ground, sieved at 105 mu m and then suspended in 0.2% v/v HNO3 and 10% v/v Triton X-100 medium. For liquid phase aluminium determination t he samples were prepared in the same way and only the liquid is introduced directly into the graphite furnace. Calibration was performed by aqueous st andards for both cases and the determinations were carried out in the linea r range between 50 and 250 mu g L-1. The characteristic mass of aluminium a nd the detection limit were 45 pg and 2 mu g L-1, respectively. Using a typ ical 0.1% m/v coffee slurry sample, the relative standard deviation of meas urements (n = 15) for repeatability was about 8.2%.