A flow injection analysis system for monitoring silver (I) ion and iodine residuals in recycled water from recovery systems used for spaceflight

• Automated FIA device for monitoring Ag+ or I2 residuals in recycled drinking water.
• Method detection limits of Ag+ of 52 μg L−1 and I2 of 2 μg L−1.
• Mean % recoveries for Ag+ of 104 ± 1% and for I2 of 96.2 ± 0.1%.
• % relative standard deviation estimates for Ag+ of 1.4% and for I2 of 5.7%.
• Bias measurements agreed to 11.3 μg L−1 for Ag+ and to 27.3 μg L−1 for I2.

A laboratory-built flow injection analyzer is reported for monitoring the drinking water disinfectants silver (I) ion and iodine in water produced from NASA's water recovery system. This analyzer uses spectrophotometric detection with a custom made 10 cm optical flow cell. Optimization and interference studies are discussed for the silver (I) ion configuration. Subsequent results using the silver (I) configuration with minor modifications and alternative reagents gave promising results for iodine determinations as well. The estimated MDL values for Ag+ and I2 are 52 μg L−1 Ag+ and 2 μg L−1 I2; the mean percent recoveries were 104% and 96.2% for Ag+ and I2 respectfully; and percent relative standard deviations were estimated at 1.4% for Ag+ and 5.7% for I2. The agreement of this potentially multifunctional analyzer to reference methods for each respective water disinfectant is measured using Bland–Altman analysis as well as more traditional estimates.

A device for on-line monitoring of the water disinfectants silver (I) ion or iodine in recycled water is presented. Simply change the reagents and the sample loop volume to switch between silver ion and iodine configurations.Figure optionsDownload as PowerPoint slide