Colorimetric Solid Phase Extraction for the Measurement of Total I (iodine, iodide, and triiodide) in Spacecraft Drinking Water

摘要

An experimental water monitoring kit for the measurement of iodine and siiver(I) was recently delivered to the International Space Station (ISS). The kit is based on Colorimetric Solid Phase Extraction (CSPE) technology, which uses diffuse reflectance spectrophotometry to measure a color change on the surface of indicator disks following exposure to a water sample. To satisfy additional spacecraft potable water monitoring requirements, CSPE has now been extended to encompass the measurement of total I (iodine, iodide, and triiodide). This is accomplished through the introduction of an oxidizing agent, which converts iodide and triiodide to iodine. The sum of the iodine, iodide, and triiodide present in the sample can then be measured using the same iodine sensitive indicator disks currently being tested on ISS. These disks detect iodine, but are insensitive to iodide and triiodide. We report here the operational considerations, design, and ground-based performance of the CSPE method for total I. The results demonstrate that CSPE technology is poised to meet NASA's monitoring requirements for total iodine in potable water.