Ammonium persulfate: A new and safe method for measuring urinary iodine by ammonium persulfate oxidation

Abstract

The chloric acid method is most commonly used to obtain accurate and reproducible measurements of iodine and removes interfering substances. Unfortunately, chloric acid is a potential hazard requiring an explosion proof hood among other precautions. We have developed a simple, convenient, and economic method for measuring urinary iodine using 1 mol/L ammonium persulfate, a non-explosive, non-hazardous chemical, as the oxidizing reagent. The oxidation procedure can be completed in 30 minutes at a temperature of 91-95 degrees C. The iodine in the urine is then measured by a modification of the traditional colorimetric method of Sandell-Kolthoff. 110 urine samples collected from a mixed population of healthy males and females, ranging in age from 6 to 79 years and living in the United States were analyzed for iodine content by two methods: the proposed ammonium persulfate method and the chloric acid method. The ammonium persulfate method has an intra assay CV of 9.1% at 0.42 +/- 0.04 micromol/L (mean +/- SD), 7.8% at 1.46 +/- 0.11 micromol/L and 4.0% at 3.54 +/- 0.14 micromol/L. The inter assay CV is 10.2% at 0.46 +/- 0.05 micromol/L and 7.9% at 3.27 +/- 0.26 micromol/L. Recovery of iodine added to urine in vitro was 107%, 94% and 97% for 0.42 micromol/L, 0.77 micromol/L and 3.64 micromol/L, respectively. The lower limit of detectability was 0.0034 microgI. Values for iodine in 110 urines measured by the reference chloric acid method ranged from 0.06 to 8.03 micromol/L and by the ammonium persulfate method from 0.05 to 7.4 micromol/L. The persulfate method (y) correlated extremely closely with the reference chloric acid method (x) by the Pearson correlation (y = 0.923x + 0.810 micromol/L, and r = 0.994, Syx = 1.841). In conclusion a new, safe, simple method for measuring urinary iodine is described which uses ammonium persulfate as the oxidizing agent for the removal of interfering substances.

Prevalence of iodine deficiency disorder Amongst Orang Asli in Hulu Selangor, Malaysia

“…Samples were kept at -20ºC prior to analysis. The samples were analyzed for iodine concentration using spectrophotometric measurement of iodine in the Sandell-Kolthoff reaction which involved an iodine catalyzed reduction of yellow ceric (IV) ions to colourless cerous (III) ions by ammonium persulfate (Pino et al, 1996). The normal population median value of urinary iodine is 100-199 µg/L, values of ≥300 µg/L and 200-299.9 µg/L suggest excessive and more than adequate respectively , while 50-99.9 µg/L, 20-49.9 µg/L and <20 µg/L suggest mild ,moderate and severe iodine deficiency respectively (WHO, UNICEF and ICCIDD, 2007).…”

Quality control of test iodine in urine by spectrophotometry UV–Vis

“…The standard solution of potassium triiodate and urine samples are treated equally as reacted using an ammonium persulfate solution. The purpose of addition of ammonium persulfate is to oxidize an interfering substance prior to Sandell-Kolltof reaction as well as iodide oxidation and other iodine components in the urine [11]. The standard curve obtained from the observation of KIO 3 standard solution is presented in Fig.…”

“…Iodine testing principle with UV-Vis spectrophotometry is by SandellKolthoff reaction [8,9] The arsenic ion (As 3+ ) is used to reduce the cerium ion (Ce 4+ ) to form Ce 3+ ions which function to oxidize iodide (I -) to iodine (I 2 ) [10,11] which can then be analyzed by UV-Vis spectrophotometry. Standard iodine solution analyzed by UV-Vis spectrophotometry will be directly proportional to the % transmittance [11] or inversely proportional to absorbance.…”

Impact of removing iodized salt on the iodine nutrition of children living in areas with variable iodine content in drinking water

“…The iodine content of urine samples was measured by the method of Sandell-Kolthoff reaction for which the basis of the analysis is the reduction of ceric ion in the presence of arsenious acid [13]. WHO defines iodine excess where an MUIC of a given population is above 300 lg/l [11].…”

“…Correlation between children's MUIC and MWICThe respective associations between MUIC and MWIC, MUIC and MSIC in the 12 villages were analyzed using SPSS13.0. For the baseline data, children's MUIC was positively correlated with the MWIC in the 12 villages (Spearman, R = 0.893, p = 0.001), though it did not correlate significantly with the MSIC of the villages (Spearman, R = -0.536, p = 0.073).…”