Determination of iodide based on dynamic gas extraction and colorimetric detection by paper modified with silver triangular nanoplates

This paper reports on a new method for sensitive and selective determination of iodide based on dynamic gas extraction with air flow and digital colorimetric detection using paper modified with silver triangular nanoplates (AgTNPs). Iodide is oxidized in a sample by Fe(III) to produce molecular iodine which is extracted in air flow and transferred to a sensitive AgTNPs-containing paper layer. Interaction of AgTNPs with iodine results in optical changes which can be monitored by ordinary scanner. The high selectivity of dynamic gas extraction to volatile compounds ensures successful analysis of such samples as cranberry and kelp with no sample pretreatment, and due to the sensitivity of AgTNPs good analytical performance can be achieved. The limit of detection of iodide was found to be of 0.01 mg L −1 and the determination range of 0.03–0.3 mg L −1. The method can be easily adapted to simultaneous determination of iodide/iodine and iodide/chloride in the same sample.