Evaluation of an Ultrasound-Assisted Digestion Method for Determination of Arsenic and Lead in Edible Citric Acid Samples by Etaas



Pourhossein A¹ ; Madani M^{1, 2} ; Shahlaei M^{3, 4}
Source: Canadian Journal of Analytical Sciences and Spectroscopy Published:2009

Abstract

In this paper, a sample preparation method based on ultrasound-assisted digestion of edible citric acid samples for trace determination of arsenic and lead is described. Final solutions obtained upon sonication were directly injected into a pyrocoated graphite furnace for fast determination by electrothermal atomic absorption spectrometry (ETAAS). Parameters influencing digestion such as sonication time, sample mass and solvent system were fully optimised. Optimum conditions for metal extraction were as follows: a 20 min sonication time, a 2.0 g sample mass (in 10 mL solvent) and a mixture of concentrated HNO3-H2O2. Limits of detection corresponding to the ultrasound-assisted digestion method were 0.27 ng mL -1 and 0.31 ng mL-1 for As and Pb, respectively. The R.S.D. for ultrasound-assisted digestion method was about 1, and 2% for As and Pb, respectively. Analytical results for the two elements by ultrasound-assisted digestion, dry ashing digestion and wet digestion methods showed a good agreement, thus indicating the possibility of using mild conditions for sample preparation instead of intensive treatments inherent with the digestion method.