Determination of inorganic anions via postcolumn reaction with iodide in ion chromatography

Kitamaki, Yuko; Jin, Jiye; Takeuchi, Toyohide

doi:10.1016/s0731-7085(02)00517-4

Cited by 10 publications

(6 citation statements)

References 10 publications

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“…The host–guest inclusion complexation of α-CD and triiodide, assuming 1:1 stoichiometry ( vide infra , to be confirmed through the analysis), is given by the following reaction and equilibrium expression: This complexation equilibrium is coupled to reaction through the I 3 – guest species. The binding of I 3 – by α-CD (according to reaction ) causes iodine to be converted into triiodide (according to reaction ) and increases the overall concentration of I 3 – in solution (as “free” I 3 – and “complexed” α-CD·I 3 – ). , This is demonstrated by the spectra in Figure where [I – ] 0 = 100 × [I 2 ] 0 . At first glance, the spectrum appears to represent just triiodide (compare Figures and ).…”

Section: Results and Discussionmentioning

confidence: 96%

Host–Guest Inclusion Complexation of α-Cyclodextrin and Triiodide Examined Using UV–Vis Spectrophotometry

Pursell

2016

J. Phys. Chem. A

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The historically relevant host-guest complexation of α-cyclodextrin (α-CD) and triiodide (I3(-)) in aqueous solution was examined using a systematic UV-vis spectrophotometric approach. This particular system is experimentally challenging because of the coupled equilibria, namely, I2 + I(-) ⇌ I3(-) and α-CD + I3(-) ⇌ α-CD·I3(-). We therefore developed a unique experimental approach that allowed us to determine the concentration of all iodine species. This enabled us to unequivocally demonstrate that the large increase in the UV absorbance with added α-cyclodextrin is due to an increase in the overall triiodide concentration as α-CD essentially converts iodine to triiodide according to the coupled equilibria. Herein we report (a) the complexation stoichiometry is 1:1 (i.e., the host-guest complex is α-CD·I3(-)), (b) the binding constant is KH-G = (1.35 ± 0.05) × 10(5) M(-1) at room temperature, and

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Section: Results and Discussionmentioning

confidence: 96%

Host–Guest Inclusion Complexation of α-Cyclodextrin and Triiodide Examined Using UV–Vis Spectrophotometry

Pursell

2016

J. Phys. Chem. A

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“…The reaction was carried out at room temperature (ca. 258C) although the postcolumn reaction temperature should be higher [17]. It is seen that the iodate signal in the upper trace is significantly enhanced compared with the lower trace.…”

Section: Signal Enhancement Of Iodatementioning

confidence: 96%

“…In contrast, the lower trace provides larger signals for bromate and nitrite, owing to the slower derivatization compared with iodate. In addition, a-cyclodextrin (CD) is present in the postcolumn reagent solution to enhance the signal [17]. The detection limit of iodate at S/N 3 under the conditions of Figure 3 was 1.6 lM or 0.32 pmol for a 0.2 lL injection volume.…”

Section: Signal Enhancement Of Iodatementioning

confidence: 99%

Postcolumn derivatization in microcolumn liquid chromatography

Takeuchi¹,

Masuoka

Jin

2003

J of Separation Science

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A postcolumn derivatization system was assembled using a commercially available Nano Y Connector with low dead volume for microcolumn liquid chromatography. Smooth baselines were achieved when postcolumn reagent solution and mobile phase were supplied by one microfeeder equipped with two syringes. Amino acids and inorganic anions were visualized by the postcolumn reaction with tolerable extracolumn band broadening.

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“…10 In that work, we found that α-cyclodextrin (α-CD) improved the sensitivity of the analyte anions, owing to the formation of an inclusion complex between α-CD and I3 -. This is because more I3 -is formed to keep the following equilibriums, where both I3 -and the complex between α-CD and I3…”

Section: Introductionmentioning

confidence: 99%

Cyclodextrin-Aided Determination of Iodate and Bromate in Drinking Water by Microcolumn Ion Chromatography with Precolumn Enrichment

Kitamaki

Takeuchi

2004

ANAL. SCI.

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Ozonization has recently replaced the chlorination of many types of water, since ozone is effective for disinfection. However, since ozone is a very strong oxidant, bromide (Br -) contained in water is also oxidized to form hypobromous acid (HOBr) or hypobromite (OBr -). The latter reacts with excess ozone to form bromate (BrO3 -), which is a disinfection byproduct. 1 The toxicity of BrO3 -has been studied, revealing that BrO3 -is carcinogenic to animals.2 Therefore, the maximum contaminant level of BrO3 -has been set at 10 µg L -1 by the U.S. Environmental Protection Agency. However, there are many problems in the determination of BrO3 -at such low levels. There have been reported several methods for the determination of BrO3 -by ion chromatography (IC). 3,4 Hautman and Bolyard 3 achieved the separation of BrO3 -from chloride (Cl ) and nitrate (NO3 -) by using tetraborate/boric acid as an eluent. Joyce and Dhillon 4 removed a large level of Cl -in the sample by a pretreatment using a silver-form cation-exchange resin. However, these methods were less selective to BrO3 -because conductometric detectors were utilized. On the other hand, the selective determination of BrO3 -with postcolumn derivatization, based on the formation of triiodide (I3 -) by the reaction of BrO3 -and iodide (I -), was proposed, but this method was not sensitive enough to determine BrO3 -in drinking-water samples. 5 Nowack et al. 6 used osmate as a catalyst in the postcolumn derivatization of ClO3 -with I -, followed by the UV detection of I3 -. Although this method is very sensitive, it may not be suitable for the determination of BrO3 -. This is because osmate is poisonous and difficult to handle. Furthermore, they had to use a hydrogen peroxide solution in the whole postcolumn system in order to remove a black precipitate (Os V ). It should be noted that the black precipitate was gradually formed in the reaction coil, which increased the background absorption and decreased the response of the target signal.Gas chromatography/mass spectrometry (GC/MS) was utilized for the selective determination of BrO3 -at ppb levels. 7 This method utilized BrO3 -as an oxidant, viz., it oxidized Br -to bromine (Br2), and the formed Br2 then reacted with styrene to produce a hydroxylbromostyrene derivative to be analyzed by GC/MS. However, this method is too complicated and troublesome to determine BrO3 -.Sensitive and selective detection procedures of BrO3 -were proposed based on the conversion of the oxidant to Br3 -by a postcolumn reaction with Br -under acidic conditions. 8,9 These methods achieved the sensitive and selective determination of BrO3 -in drinking water. They had to use a rather complicated pumping system, viz., three pumps for providing the eluent for IC, sodium bromide (NaBr) as the postcolumn reagent, and sulfuric acid (H2SO4). H2SO4 was used to convert NaBr into hydrobromic acid (HBr) using a suppressor, followed by a postcolumn reaction.We previously reported on the determination of iodate (IO3 -) and nitrite (NO2 -) as I3 -via a po...

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Determination of inorganic anions via postcolumn reaction with iodide in ion chromatography

Cited by 10 publications

References 10 publications

Host–Guest Inclusion Complexation of α-Cyclodextrin and Triiodide Examined Using UV–Vis Spectrophotometry

Host–Guest Inclusion Complexation of α-Cyclodextrin and Triiodide Examined Using UV–Vis Spectrophotometry

Postcolumn derivatization in microcolumn liquid chromatography

Cyclodextrin-Aided Determination of Iodate and Bromate in Drinking Water by Microcolumn Ion Chromatography with Precolumn Enrichment

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