Kazuaki Ito

Determination of Iodide in Seawater by Ion Chromatography

A simple and highly sensitive ion chromatographic method with UV detection was developed for iodide (I(-)) in seawater. A high-capacity anion-exchange resin with polystyrene-divinylbenzene matrix was used for both preconcentration and separation of iodide. Iodide in artificial seawater (salinity, 35‰) was trapped quantitatively (98.8 ± 0.6%) without peak broadening on a preconcentrator column and was separated with 0.35 M NaClO(4) + 0.01 M phosphate buffer (pH 6.1). On the other hand, the major anions in seawater, chloride and sulfate ions, were partially trapped (5-20%) and did not interfere in the determination of I(-). The detection limit for I(-) was 0.2 μg/L for 6 mL of artificial seawater. The present method was applied to determination of I(-) (ND - 18.3 μg/L) and total inorganic iodine (I(-) + IO(3)(-) - I, 50.0-52.7 μg/L) in seawater samples taken near Japan.

Detection of domestic wastes in Kurose river using synchronous fluorescence spectroscopy

Abstract This study was conducted to determine the applicability of synchronous fluorescence spectroscopy (SFS) in differentiating natural organic matter (NOM) from dissolved organic matter (DOM) derived from domestic wastes and in detecting their presence in Kurose River. Sewage effluent, gray water, water extracts from leaf mold and top soil, respectively, algal culture media, and water samples from different points of the river were analyzed. A laboratory mixing experiment was conducted by combining the leaf mold water extract (LM-NOM) and sewage effluent at different ratios. The SFS of the samples were run at offset value of Δλ=40xa0nm (Δλ=λem−λex). The corrected synchronous fluorescence spectra of LM-NOM and the sewage effluent showed different spectral features. A very intense peak at about 531xa0nm was observed in the sewage effluent spectrum which was not found in the LM-NOM sample. The mixing of fluorescing organic material in LM-NOM and sewage effluent resulted in the simple addition of their respective spectra. This allows the detection of pollutants in surface waters by the appearance of characteristic peaks of the added wastewater. The corrected spectra of the river water sample from a relatively unpolluted point of Kurose River exhibited a simple spectrum with a single peak while the spectra of those collected downstream showed peaks similar to those found in the sewage effluent and gray water spectra. These results demonstrate the applicability of SFS in detecting the presence of different DOM in surface waters.

Semi-micro ion chromatography of iodide in seawater

Abstract Large sample volume injections including both on-column analyte focusing and on-column matrix elimination techniques were examined for semi-micro ion chromatography of trace iodide (I − ) in seawater. A semi-microcolumn (35×1 mm I.D.) packed with styrene–divinylbenzene copolymer with high anion-exchange capacity and a mobile phase of 0.03 M NaClO 4 +0.5 M NaCl+5 m M sodium phosphate buffer, pH 6.0, was used. Iodide in seawater was effectively concentrated on the column by both electrostatic and hydrophobic interactions and was eluted without peak broadening. ClO 4 − (NaClO 4 ) in the mobile phase was effective for the elution of iodide and Cl − (NaCl) for both the concentration of iodide (I − ) with hydrophobicity and the removal of interference by the major anions. An excess of major anions in seawater did not disturb the detection of iodide at UV 226 nm. The relative standard deviations for successive injections of 5 and 1 μg/l I − (2 ml of 35‰ artificial seawater) were 1.5 and 5.8% ( n =5, each), respectively. The slope of calibration curve (by peak area) using the semi-microcolumn was ∼2.8-times higher than that for a conventional column with the same resin (150×4.6 mm I.D.) The present method had a detection limit of 0.2 μg/l I − for 2 ml of 35‰ artificial seawater and was successfully applied to seawater samples.

Ion chromatography of inorganic iodine species using C18 reversed-phase columns coated with cetyltrimethylammonium

Abstract Low-capacity anion-exchange columns were developed by sorption of cetyltrimethylammonium on two types of C18 reversed-phase columns which were coated with 1 mM cetyltrimethylammonium in water-methanol mixtures (57:43, v/v, to 45:55, v/v) at 20°C. The exchange capacities of the columns were estimated by three methods. The high separation efficiency for anions was performed by using a 0.1 M sodium chloride-5 mM sodium phosphate buffer (pH 5.8) as mobile phase. An ion chromatographic system for iodide consisted of the column (polymer-coated silica packing) coated with 1 mM cetyltrimethylammonium in water-methanol (56:44%, v/v), the sodium chloride mobile phase, and ultraviolet or amperometric detection. Good chromatograms for iodide in surface sea waters were obtained without interference by an excess of salts.

Trihalomethane formation potential prediction using some chemical functional groups and bulk parameters

Abstract This study was conducted to determine the influence of some chemical functional groups (COOH, phenolic-OH and organic nitrogen) and bulk parameters (UV 260 and DOC) on the trihalomethane formation potential (THMFP) of various treated industrial wastewaters. The samples were analyzed for UV 260, DOC, and THMFP. They were further fractionated into hydrophobic (humic) and hydrophilic (nonhumic) fractions using the XAD-8 resin, then bulk and specific chemical functional groups were determined on both fractions. Regression analyses were carried out among the parameters analyzed with THMFP as the dependent variable. The hydrophilic fractions contained higher DOC and had larger contribution to the bulk THMFP compared to the hydrophobic fractions. Simple regression analysis showed that although UV 260 and DOC correlated better with THMFP, the correlation values obtained were not statistically significant. Correlations using bulk parameters as well as chemical functional groups taken one at a time could not predict THMFP. The parameters that influenced the formation of THMs based on a stepwise and multiple regression analyses were UV 260, organic nitrogen, and phenolic-OH in the nonhumic fractions (hydrophilic) and UV 260 and organic nitrogen in the humic fractions (hydrophobic). The estimated THMFP obtained from the equation derived from the statistical analyses correlated significantly with the observed values at 99% level of confidence.

Separation of alkali and alkaline-earth metal and ammonium cations by capillary electrophoresis using poly(ethylene glycol) and tartaric acid

The separation behavior of alkali and alkaline-earth metal and ammonium cations was investigated by capillary electrophoresis (CE) using poly(ethylene glycol) (PEG) and tartaric acid (H2 Tar) as electrolyte systems. Creatinine was used as a visualized co-ion for indirect UV detection (254 nm). Separation of all the analyte cations increased with the volume fraction of PEG in water and the decrease in mobility for alkaline-earth metal cations was larger than that for alkali metal cations. The separation of alkaline-earth metal cations was also enhanced by complex formation with tartarate ions, resulting in decreased mobility. Addition of H2 Tar in water-PEG (50:50, v/v) had a larger effect than addition to water alone, suggesting larger stability constants with alkaline-earth metal cations. The separation pattern of alkaline-earth metal cations by H2 Tar in water was in good agreement with the results calculated. Thus, the group separation of monovalent and divalent cations, respectively, and also the complete separation of all cations were shown for the electrolyte systems of PEG and H2 Tar.

Ion chromatography with ultraviolet and amperometric detection for iodide and thiocyanate in concentrated salt solutions

Abstract An ion chromatographic system with ultraviolet (UV) and amperometric (AMP) detectors is described for the highly sensitive detection of iodide and thiocyanate. Solutions of four inorganic salts as mobile phases and three stationary phases were examined. The optimum separation was achieved by using a polymethacrylate-based anion-exchange column and 0.1 M sodium chloride—5 mM sodium phosphate buffer (pH 6.7) as the mobile phase. Conditions were established for UV and AMP detection on a electrochemically pretreated glassy carbon electrode. The method, which has the ability to eliminate most interferences from other anions, could be applied to the direct determination of ppb levels of iodide in sea water.

Effect of HRT and MLSS on THM precursor removal in the activated sludge process

Abstract This study was conducted to evaluate the effect of hydraulic retention time (HRT) and mixed liquor suspended solids (MLSS) on trihalomethane (THM) precursor removal in the activated sludge process and to determine the effect of chemical properties of the organic components on trihalomethane formation potential (THMFP). A laboratory-scale reactor for the activated sludge process was used with synthetic domestic wastewater as influent. Experimental conditions, HRT and MLSS, were varied and the effluents were evaluated in terms of DOC and THMFP. Hydrophilicity, hydrophobicity and chemical functional groups were analyzed to determine the chemical parameters that may affect THMFP. Optimum removal of THMFP was achieved at HRT 24xa0h and at MLSS of ca. 2500xa0mgxa0l −1 . Due to the organic metabolites produced in the activated sludge floc, better DOC or THMFP removal was not observed at longer HRTs and larger MLSS. Decrease in DOC did not result in comparable removal of THMFP. This was attributed to two factors: the higher reactivity of the hydrophobic organic carbon (18.5xa0 μ g THMFPxa0mg −1 C) compared to the hydrophilic organic carbon (6.2xa0 μ g THMFPxa0mg −1 C) and the nonremoval of the remaining hydrophobic THM precursors in HRTs longer than 8xa0h. The activated sludge process preferentially removed the hydrophilic organic substances which was shown to have less potential to form THM. The activated sludge process effluents exhibited similar chemical characteristics compared with various types of treated industrial wastewaters determined in a previous study. The activated sludge process effluents contained larger amounts of the hydrophilic organic substances compared to the hydrophobic fractions. Larger amounts of the carboxylic and phenolic-OH functional groups were determined in the hydrophilic fractions than in the hydrophobic fractions. The equation obtained for THMFP prediction based on bulk parameters and specific functional groups of the treated industrial wastewaters was also found to be applicable on the activated sludge process effluents. The equation suggests that bulk THMFP was influenced by UV 260 and organic nitrogen of both the hydrophilic and the hydrophobic fractions, and phenolic-OH of the hydrophilic fractions.

Determination of inorganic anions in salt solutions by ion chromatography using C18 reversed-phase columns coated with cetyltrimethylammonium

Abstract A simple and sensitive method using ion chromatography is described for the determination of I−, SCN−, NO−2 and S2O2−3 as impurities in inorganic analytical-reagent grade chemicals. Aqueous solutions of individual salts containing matrix anions (5–20 g/l) were prepared and analyzed directly for trace impurities. Good chromatograms of trace anions were obtained without interference by matrix ions. C18 reversed-phase columns coated with cetyltrimethylammonium (CTA+), with either high or low capacity, a mobile phase mixture (pH 5.8) of sodium chloride (0.1 M) and sodium phosphate buffer (0.005 M), and ultraviolet (225 nm) and amperometric (+ 1.0 V vs. Ag/AgCl) detection systems were used. The detection limits for different impurities in the solutions were 0.002–0.06 mg/l.

Separation and detection of common mono- and divalent cations by ion chromatography with an ODS column and conductivity/UV detection

The retention and detection behavior of common mono- and divalent cations (M+, alkali metal (Li+, Na+, K+, Rb+, Cs+) and ammonium ions (NH4+); M2+, alkaline earth metal ions (Mg2+, Ca2+, Sr2+, Ba2+) was examined using an ODS column (150 x 4.6 mm I.D.) and conductivity (CD)/UV detection. The results obtained were as follows: (1) for M+, the mobile phase, 0.1 mM sodium dodecyl sulphate (SDS) + 10 mM HNO3 and indirect CD detection were effective. (2) Addition of Ce(III) in the mobile phase accelerated the elution of both M+ and M2+. The separation of above 10 cations on an ODS column was achieved for the first time without any coelution of cations and disturbance by system peak. Addition of higher SDS resulted in good separation of M+ and M2+ with longer retention times. CD detection was possible for M+ and M2+ and UV detection for M2+. (3) For M2+, the mobile phase, 0.8 mM Ce(III) + 0.1 mM SDS + 1 mM HNO3 and indirect UV detection were effective. The IC methods were applied to real samples.