MnFe2O4 Micromotors Enhanced Field Digestion and Solid Phase Extraction for On-Site Determination of Arsenic in Rice and Water

ABSTRACT Despite the increased interest and great progress obtained on arsenic test, it is still a challenge to accomplish the on-site determination of arsenic in rice due to the expensive instrumentation and harsh digestion process. In this work, MnFe2O4 micromotors were found to retain high catalytic activity to simultaneously produce large amounts of hydroxyl radicals and O2 bubbles in the presence of H2O2. Interestingly, the generated bubbles autonomously propel the micromotors and prevent them from depositing, thus keeping their high catalytic activity. As a result, an MnFe2O4 micromotors enhanced digestion method was developed for the field digestion of rice samples within 100 min only using H2O2, which was further utilized to realize the on-site detection of arsenic in rice by coupling with the Gutzeit method followed headspace solid phase extraction. A quantification limit of 40 μg kg−1 was obtained for the determination of arsenic in rice. Owing to their capabilities of the efficient and rapid adsorption of arsenic and continuous movement, a MnFe2O4 micromotors enhanced solid phase extraction was also established for the sensitive determination of arsenic in water with a 1 μg L−1 of quantification limit. The accuracy of the developed method was validated via analysis of a Certified Reference Material of rice (GBW10043) and a series of rice and water samples with satisfactory results, showing promising potential in the sensitive on-site detection of arsenic in rice and water samples.