An improved method for total organic iodine in drinking water.
A concise, rapid, and sensitive method is developed to measure organically-bound iodine in water. Total organic iodine (TOI) is used as an integrative surrogate that reflects the amount of iodinated organics in a water sample and is quantified using a refined method that builds on previous adsorption and detection approaches. The proposed method combines adsorption, combustion, and trapping of combustion products, with an offline inductively coupled plasma/mass spectrometer (ICP-MS) for iodide detection. During method development, three analytical variables (factors) were varied across two levels each in order to optimize the method for iodine recovery: 1) the sample pH prior to adsorption on the granular activated carbon (GAC); 2) the amount of base addition to the trap solution; and 3) composition of the ICP-MS wash solution. These factors were tested with solutions of eight iodinated model organic compounds, two iodinated inorganic compounds, and field water samples using a full factorial experimental design. An analysis of variance (ANOVA) and related statistical methods were deployed to identify the best combination of conditions (i.e., treatment) that results in the most complete recovery of iodine from the model compounds and the highest rejection of inorganic iodine. The chosen treatment for TOI measurement incorporates a sample pH of less than 1 prior to adsorption onto the GAC, a solution of 2% (v/v) tetramethyl ammonium hydroxide (TMAH) for trapping of combustion products, and a TMAH wash solution of 0.1% (v/v) for the ICP-MS.
Department of Environmental and Water Resources Engineering, University of Massachusetts, Amherst, 01003, United States. Electronic address: rasilsayess@gmail.com.
Rassil
R
Sayess
Department of Environmental and Water Resources Engineering, University of Massachusetts, Amherst, 01003, United States.
David A
DA
Reckhow
D060766:Drinking Water; D007454:Iodides; D007455:Iodine / Q000737:chemistry*; D017613:Iodine Compounds; D013058:Mass Spectrometry; D014874:Water Pollutants, Chemical / Q000737:chemistry
D060766:Drinking Water; D007454:Iodides; D017613:Iodine Compounds; D014874:Water Pollutants, Chemical; D007455:Iodine
Analytical techniques; Drinking water; ICP-MS; Iodinated disinfection by-products; Total organic iodine