MnFe2O4 micromotors enhanced field digestion and solid phase extraction for on-site determination of arsenic in rice and water

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, MnFe 2 O 4 micromotors were found to retain high catalytic activity to simultaneously produce large amounts of hydroxyl radicals and O 2 bubbles in the presence of H 2 O 2 . Interestingly, the generated bubbles autonomously propel the micromotors and prevent them from depositing, thus keeping their high catalytic activity. As a result, a MnFe 2 O 4 micromotors enhanced digestion method was developed for the field digestion of rice samples within 100 min only using H 2 O 2 , 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 MnFe 2 O 4 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.