Comparison between ultrasound assisted extraction and microwave digestion in the determination of arsenic in edible grains

Abstract

A comparative evaluation of arsenic extraction from grains using ultrasound assisted extraction (UAE) and microwave digestion (MW) was developed. The arsenic determination was carried out using hydride generation coupled to flame atomic absorption spectroscopy (HG-FAAS). The optimal extraction condition indicated for corn was 20% v v-1 of HCl, temperature of 67 °C and sonication time of 30 min. For bean, the optical condition was HNO3 in a 10% v v-1, temperature of 25 °C and sonication time of 10 min and for soybean it was 30% v v-1 HCl, temperature of 60 °C and time of 10 min. Recovery studies close to 100% in the extraction of spiked samples was achieved. The results obtained were compared with two common extraction methods for arsenic using microwave digestion and the developed methods showed a significant increase in the arsenic recovery from the samples. In the real samples it was found an arsenic concentration of 0.3 μg g-1. The developed methods proved to be efficient at extracting the arsenic present in the studied grains, being appropriate to evaluate the risk to human consumption.