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Rapid, specific determination of iodine and iodide by combined solid-phase extraction/diffuse reflectance spectroscopyA new, rapid methodology for trace analysis using solid-phase extraction is described. The two-step methodology is based on the concentration of an analyte onto a membrane disk and on the determination by diffuse reflectance spectroscopy of the amount of analyte extracted on the disk surface. This method, which is adaptable to a wide range of analytes, has been used for monitoring ppm levels of iodine and iodide in spacecraft water. Iodine is used as a biocide in spacecraft water. For these determinations, a water sample is passed through a membrane disk by means of a 10-mL syringe that is attached to a disk holder assembly. The disk, which is a polystyrene-divinylbenzene composite, is impregnated with poly(vinylpyrrolidone) (PVP), which exhaustively concentrates iodine as a yellow iodine-PVP complex. The amount of concentrated iodine is then determined in only 2 s by using a hand-held diffuse reflectance spectrometer by comparing the result with a calibration curve based on the Kubelka-Munk function. The same general procedure can be used to determine iodide levels after its facile and exhaustive oxidation to iodine by peroxymonosulfate (i.e., Oxone reagent). For samples containing both analytes, a two-step procedure can be used in which the iodide concentration is calculated from the difference in iodine levels before and after treatment of the sample with peroxymonosulfate. With this methodology, iodine and iodide levels in the 0.1-5.0 ppm range can be determined with a total workup time of approximately 60 s with a RSD of approximately 6%.
Document ID
20040088504
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Arena, Matteo P. (Ames Laboratory-USDOE, and Iowa State University Ames, Iowa 50011, United States)
Porter, Marc D.
Fritz, James S.
Date Acquired
August 21, 2013
Publication Date
January 1, 2002
Publication Information
Publication: Analytical chemistry
Volume: 74
Issue: 1
ISSN: 0003-2700
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: NAG9-1191
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Environmental Health