Study of chemical modifiers for the direct determination of antimony in soils and sediments by ultrasonic slurry sampling-ETAAS with D-2 compensation

The direct determination of antimony in soils by ultrasonic slurry sampling electrothermal atomic absorption spectrometry (USS-ETAAS) in soils and sed -iments is hampered by spectral interferences that are not completely remov ed by deuterium background correction. However, an accurate and precise met hod can be established based on peak height evaluation. Considering these c onditions, the chemical modifiers have to be evaluated and optimized in a d ifferent way. Seven chemical modifiers for the direct determination of anti mony in soils by USS-ETAAS were compared by optimizing the furnace temperat ure programs for each modifier and their appropriate amounts to get the hig hest signal and better separation between the atomic peak and background si gnal. Nitric acid (0.5% v/v) was found to be the most adequate chemical mod ifier for antimony determination. The optimum pyrolysis and atomization tem peratures were set at 900 degrees C and 1700 degrees C, respectively. As de uterium background correction was not adequated, peak height was used. It p eas found that interferent ions caused a profound effect in the aqueous sol utions but not in the slurries. The figures of merit of the optimized metho d were 17.3 +/- 1.71 pg for the characteristic mass and 0.025 mu g g(-1) (1 .24 ng mL(-1)) for the limit of detection. The within-sample and overall-me thod precision were highly satisfactory (< 7%, RSD). No statistical differe nces were observed between the experimental and certified concentrations fo r three certified reference soils (recoveries ranged from 93 to 110%). Addi tionally, two certified sediments were assayed as an attempt to extend the optimized methodology to the Sb determination in sediment samples. Good res ults were also obtained (recoveries from 82 to 109%).