Determination of trace concentrations of bromate in municipal and bottled drinking waters using a hydroxide-selective column with ion chromatography

The International Agency for Research on Cancer determined that bromate is a potential human carcinogen, even at low micro/l levels in drinking water. Bromate is commonly produced from the ozonation of source water containing naturally occurring bromide. Traditionally, trace concentrations of bromate and other oxyhalides in environmental waters have been determined by anion exchange chromatography with an IonPac AS9-HC column using a carbonate eluent and suppressed conductivity detection, as described in EPA Method 300.1 B. However, a hydroxide eluent has lower suppressed background conductivity and lower noise compared to a carbonate eluent and this can reduce the detection limit and practical quantitation limit for bromate. In this paper, we examine the effect of using an electrolytically generated hydroxide eluent combined with a novel hydroxide-selective anion exchange column for the determination of disinfection byproduct anions and bromide in municipal and bottled drinking water samples. EPA Methods 300.1 B and 317.0 were used as test criteria to evaluate the new anion exchange column. The combination of a hydroxide eluent with a high capacity hydroxide-selective column allowed sub-microg/l detection limits for chlorite, bromate, chlorate, and bromide with a practical quantitation limit of 1 microg/l bromate using suppressed conductivity detection and 0.5 microg/l using postcolumn addition of o-dianisidine followed by visible detection. The linearity, method detection limits, robustness, and accuracy of the methods for spiked municipal and bottled water samples will be discussed.     

抑制型电导检测离子色谱法测定饮用水中的痕量溴酸盐

建立一种直接进样测定饮用水中痕量溴酸盐的电导检测离子色谱法。选用Metrosep A Supp 5阴离子交换分离柱,碳酸盐淋洗液。抑制型电导检测采用化学抑制器和CO2抑制器顺序双抑制系统。实验结果显示,溴酸根阴离子与常见共存阴离子完全分离,溴酸盐含量在5~100 μg/L范围内具有良好的线性(r=0.9999),精密度高(相对标准偏差（RSD）<4%),方法的检出限为0.50 μg/L,样品加标平均回收率为96.1%~107%。该方法操作简单,分离效果好,可与常见阴离子实现同时分析,灵敏度高,重现性好,可作为饮用水中溴酸盐的标准测定方法。     

Determination of low levels of bromide in fresh water after chromatographic enrichment

A method has been developed for the determination of bromide in fresh water. The analyte is enriched on the anion-exehanger Dowex 1 x 8, which exhibits a considerably greater affinity for bromide than for the major anions in fresh water. Sodium perchlorate is used as eluent and an enrichment factor of ~100 can be achieved. The eluted bromide is oxidized with peroxodisulphate to bromate, which is determined iodometrically by a previously published spectrophotometric method. The enrichment in the presence of the major components of fresh water has been studied. Only bicarbonate has been found to interfere, but this interference can be avoided by acidifying the sample with hydrochloric acid. The recovery from synthetic fresh water with ionic concentrations corresponding to 0.005 equivalent/l. and spiked with bromide was 100% at bromide concentrations larger than 50 nM (4 mug l. ) and about 90% at 10 nM. The detection limit is 1.5nM and the limit of determination 5nM for 1-litre samples.     

Ion chromatography determination of trace level bromate by large volume injection with conductivity and spectrophotometric detection after post column derivatisation

Bromate is a well known by-product produced by the ozonisation of drinking water; the allowed concentration for human consumption has to be regulated to the low microg l(-1) range. A direct injection, ion chromatographic method was developed using a tetraborate eluent with serially connected conductivity and spectrophotometric detection. Bromate was detected after post-column reaction with fuchsin at 520 nm. Sample capacity was investigated by injecting large volumes (up to 6 ml) using a high total hardness and chloride tap water. Linear correlation of bromate response with volumes from 1 ml to 6 ml was demonstrated, the main limitation being the overlapping of the chloride peak with bromate. Up to 1.5 ml sample can be injected without any pre-treatment. With more than 1.5 ml injection volume, a sample pre-treatment with a cartridge in Ag and H form, followed by a 10 min degassing in an ultrasonic bath, was needed. This method was validated by analysing secondary reference materials and real samples from a drinking water treatment plant. The method was linear from the limit of quantification to 20 microg l(-1). Reproducibilities in tap water were 18% (5 microg l(-1), n=12) and 21% (1 microg l(-1), n=4) respectively for 1.5 and 6 ml injection volumes with conductivity detection, and 17% at 0.5 microg l(-1) (n=9) with spectrophotometric detection. Calculated detection limits were 0.5 microg l(-1) (6 ml) ahd 2 microg l(-1) (1.5 ml) for conductivity detection and 0.3 microg l(-1) (1.5 ml) for spectrophotometric detection.     

Combination of suppressed and non-suppressed ion chromatography with atmospheric pressure ionization mass spectrometry for the determination of anions

Non-suppressed and suppressed ion chromatography in combination with atmospheric pressure ionization mass spectrometry are compared with special respect to sensitivity for the analysis of low-molecular-mass anions. Iodate, bromate, bromide, sulfate, thiosulfate and bromide could be separated by non-suppressed ion chromatography using a low-capacity anion-exchange column and ammonium citrate as mobile phase. Absolute detection limits between 0.4 and 0.7 ng could be achieved; employing a column requiring a flow-rate of 1 ml/min for optimum performance, splitting was necessary so that only 120 μl/min entered the interface of the mass spectrometer resulting in detection limits between 0.03 and 0.06 mg/l. The same stationary phase (packed into a narrow-bore column which allowed operation without splitting) was suitable for the separation of oxyhalides in the suppressed mode with detection limits of 0.5 μg/l (50 pg) with sodium carbonate as eluent. The method was applied to the analysis of drinking water for oxyhalides. The sample pretreatment for the removal of matrix anions (sulfate, chloride and hydrogencarbonate) is described.     

大体积进样-浓缩柱在线富集-离子色谱法测定水中痕量及超痕量溴酸盐

建立了一种测定水中痕量及超痕量溴酸盐的在线富集大体积进样离子色谱法。采用实验室常备的柱容量较高的Dionex IonPac AG23保护柱作为浓缩柱,连接在定量环处富集溴酸盐。淋洗液自动发生装置在线生成高纯度氢氧化钾淋洗液进行梯度洗脱,抑制电导检测。实验结果表明:溴酸盐质量浓度范围在0.05~51.2 μg/L之间时线性关系良好,相关系数r≥0.9995,方法检出限为0.01 μg/L。与常规进样相比,进样量可高达5 mL,浓缩因子约为240倍。本方法成功应用于市售纯净水中溴酸盐的测定,2个加标水平的回收率在90%~100%之间,RSD(n=6)为2.1%~6.4%。该方法无需前处理,操作简单,准确度和精密度良好。通过大体积进样实现高倍富集,适用于痕量及超痕量溴酸盐的分析。     

Determination of bromide, bromate and other anions with ion chromatography and an inductively coupled plasma mass spectrometer as element-specific detector

An implementation of the Dionex IonPac AS12A analytical column with an element-specific ICP-MS detection is described for the simultaneous determination of halogen and oxyhalogen anions, sulfate, phosphate, selenite, selenate and arsenate. The chromatographic separation was achieved in less than 4 min with an aqueous 11 mM (NH4)2CO3 (pH 11.2, adjusted with aqueous ammonia) as eluent. Special emphasis was given to optimize the ICP-MS detection conditions for the reliable detection (RSD<5%) of bromate and bromide at a bromine concentration level of 1.0 microg l(-1) with 50 microl sample injection volume. In order to achieve the highest detector response for bromine species an ultrasonic nebulizer equipped with a membrane desolvator had to be employed. The detection limits (S/N=3, sample injection volume 50 microl) obtained with the IC-ICP-MS after the optimization were 0.67 microg l(-1) for BrO3-, 0.47 microg l(-1) for Br-, 69 microg l(-1) for ClO2-, 4 microg l(-1) for Cl-, 47 microg l(-1) for ClO3-, 13 microg l(-1) for SO4(2-), 36 microg l(-1) for PO4(3-), 0.4 microg l(-1) for SeO3(2-), 0.3 microg l(-1) for SeO4(2-), and 0.4 microg l(-1) for AsO4(3-).     

微波浓缩-离子法测定饮用水中的痕量溴酸根和高氯酸根

 建立了一种简便的用于浓缩水中痕量BrO3 -和ClO4 -的样品前处理方法。水样经OnGuardAg柱过滤 ,用微波炉在 15min内可浓缩 2 0倍 ,所测离子的回收率均高于 90 %。又采用IonPacAS16型亲水性柱 ,用 15 0 μL定量环 ,以NaOH为流动相、梯度淋洗方式 ,在 35min内测定了包括BrO3 -和ClO4 -在内的 8种离子。BrO3 -和ClO4 -的检测限分别为 0 10 μg/L和 0 2 0 μg/L。该方法在实际应用中有较大的参考价值。     

Measurement of penbutolol and 4-hydroxypenbutolol in plasma or serum by HPLC

A simple HPLC method for penbutolol and 4-hydroxypenbutolol assay has been developed. Plasma or serum (200 microliters) is vortex-mixed (30 s) with Tris solution (2 M, pH 10.6) containing an internal standard (50 microliters) and methyl t-butyl ether (200 microliters). After centrifugation, the extract (100 microliters) is analysed using an unmodified silica column (250 x 5 mm ID) and iso-octane-methanol-methyl t-butyl ether (55:25:20) containing ammonium perchlorate (10 mM, pH 5.7) as eluent and with fluorescence detection. No interference has been encountered and the limit of accurate measurement for both compounds is 5 micrograms/l.     

Rapid and direct determination of iodide in seawater by electrostatic ion chromatography

An electrostatic ion chromatographic (IC) method for rapid and direct determination of iodide in seawater is reported. Separation was achieved using a reversed-phase ODS packed column (250x4.6 mm I.D.) modified by coating with Zwittergent-3-14 micelles, with an eluent comprising an aqueous solution containing 0.2 mM NaClO4 and 0.3 mM Zwittergent-3-14 and using UV detection at 210 nm. Samples prepared by dissolving NaIO3, NaNO2, NaBr, NaBrO3, NaNO3, NaI, and NaSCN in artificial or real seawaters were analyzed using this IC system. Nitrite, iodate, bromide, bromate, and nitrate showed very little or no retention, while iodide and thiocyanate were well separated, being eluted within 6 and 16 min, respectively. The detection limit for iodide obtained by injecting 400 microL of sample was 0.011 microM (S/N = 3), and the precision values obtained by analyzing samples containing 0.1 or 0.3 microM iodide in real seawater samples were 2.3% RSD and 1.2% RSD, respectively. Direct determination of iodide in real seawater samples was possible using this proposed IC system.     

Simultaneous measurement of volatile sulfur compounds using ascorbic acid for oxidant removal and gas chromatography-flame photometric detection

The use of Eriochrome Black T in an alkaline, 40% methanol solution was found to be appropriate as post-column reagent for the determination of rare earths by ion chromatography. Detection of individual lanthanides and lanthanum was carried out at 512 nm and 650 nm after separation by dynamic cation exchange chromatography with gradient elution on C18 column and employing a solution containing alpha-hydroxyisobutiric acid/sodium octanesulfonate at pH 3.8 as eluent. The effect of the presence of micelles in the post-column reagent was studied. Sensitivities obtained by the addition of the cationic surfactants cetylpyridinium chloride (CPC) and hexadecyltrimethylammonium bromide (CTAB) were lower than those measured without surfactant addition. In some cases, the signal was totally suppressed. No change in sensitivity was observed with non-ionic (Triton X-100) or anionic (sodium dodecylsulphate, SDS) surfactants but a slight improvement in the baseline noise was observed with the SDS. An evaluation of the influence of chemical and operational variables on the post column reaction (PCR) reagent was carried out either by spectrophotometric tests or by chromatographic experiments. A comparison was performed between three PCR reagents: Eriochrome Black T and xylenol orange in the presence of a cationic surfactant and arsenazo III. Calibration response was linear up to an analyte concentration of 5.0 micrograms ml-1. Absolute detection limits lower than 7 and 17 ng were obtained at the detection wavelengths of 650 nm and 512 nm respectively, for all the natural lanthanides and lanthanum.     

Capillary electrophoretic determination of inorganic anions in the drainage and surface water samples.

Capillary electrophoresis was used for separation and quantitation of several inorganic anions in the drainage and surface water samples from the region with extensive use of fertilisers. Baseline separation of 13 small anions including nitrite and nitrate up to the concentrations of 100 mg/l was achieved in less than 5 min. The electrolyte consisted of 3 mM K2CrO4, 30 microM cetyltrimethylammonium bromide and 3 mM boric acid at pH 8. The method yielded precisions of 1.8-7.2% (RSD, n = 10) and detection limits from 4 micrograms/l (Cl-) up to 500 micrograms/l (citrate). The results of the CE method were compared to ion chromatography using water-acetonitrile (86:14) at pH 8.6 adjusted with NaOH as the mobile phase and consistent results were obtained.     

Separation and sensitive determination of i-urobilin and 1-stercobilin by high-performance liquid chromatography with fluorimetric detection.

i-Urobilin and 1-stercobilin were separated by high-performance liquid chromatography on a reversed-phase octadecylsilane-bonded column and detected fluorimetrically through formation of phosphor with zinc ions in the eluent. The separation and the intensity of the fluorescence response were affected by concentrations of zinc acetate and sodium borate buffer, pH and methanol content in the eluent. The optimal eluent used consisted of 0.1% zinc acetate in 75 mM boric acid buffer (pH 6.0)-methanol (25:75). The detection limit was 0.2 microgram/l for both i-urobilin and 1-stercobilin (signal-to-noise ratio 2), which makes the method 250-2500 times more sensitive than conventional methods.     

Determination of phenoxyacid herbicides in water

Novel clean-up techniques for a polymeric precolumn (PLRP-S) for the subsequent determination of bentazone and eight phenoxy acid herbicides in surface water samples are described. After preconcentration of the components at pH 3 on a 10 x 2 mm I.D. precolumn, the technique consists of a clean-up with 1000 microliters of 0.1 mol/l sodium hydroxide solution (pH 12.5) and of a heartcut consisting of four precolumn bed volumes of eluent directed to waste followed by ten precolumn bed volumes of eluent directed to the analytical column. Analytical separation is performed with acetonitrile-water (30:70) containing 0.005 mol/l of tetrabutylammonium hydrogensulphate (pH 8.3) (which is also the desorption eluent during heartcutting) on a polymeric analytical column (PLRP-S). With 25 ml of surface water, spiked at 0.25 and 1 microgram/l, applied to the precolumn, recoveries for all components were over 85% with a relative standard deviation (n = 5) of ca. 9% at 0.25 microgram/l and ca. 2% at 1 microgram/l. Detection limits in surface water samples are 0.05-0.1 microgram/l. Owing to automation, the total analysis time is ca. 30 min.     

Simultaneous determination of inorganic disinfection by-products and the seven standard anions by ion chromatography

For the first time, an ion chromatographic method for the simultaneous determination of the disinfection by-products bromate, chlorite, chlorate, and the so-called seven standard anions, fluoride, chloride, nitrite, sulfate, bromide, nitrate and orthophosphate is presented. The separation of the ten anions was carried out using a laboratory-made high-capacity anion-exchanger. The high capacity anion-exchanger allowed the direct injection of large sample volumes without any sample pretreatment, even in the case of hard water samples. For quantification of fluoride, chloride, nitrite, sulfate, bromide, nitrate, orthophosphate and chlorate, a conductivity detection method was applied after chemical suppression. The post-column reaction, based on chlorpromazine, was optimized for the determination of chlorite and bromate. The method detection limit for bromate measured in deionized water is 100 ng/l and for chlorite, it is 700 ng/l. In hard drinking water, the method’s detection limits are 700 ng/l (bromate) and 3.5 μg/l (chlorite). The method’s detection limits for the other eight anions, determined by conductivity detection, are between 100 μg/l (nitrite) and 1.6 mg/l (chlorate).     

Determination of Inorganic Anions by Capillary IC Using Hexadimethrine Bromide-Modified Silica Stationary Phases

A simple, rapid and highly sensitive capillary ion chromatographic method for direct determination of iodide and thiocyanate is reported. Separation was achieved on a laboratory-made capillary column (100 mm × 0.32 mm i.d.) packed with silica gel, followed by modification with 20 mM hexadimethrine bromide. Sodium perchlorate?Cmethanol (95:5, v/v) was used as the eluent and analyte anions were detected at 225 nm. Iodate, bromate, nitrate, iodide and thiocyanate were eluted within 8 min, with relative standard deviations of the retention time, peak area and peak height smaller than 2.4%. Effects of the eluent composition on the retention behavior were also investigated. The limit of detection (S/N = 3) of iodide was 6.5 ??g L^?1, whereas that of thiocyanate was 16.2 ??g L^?1. The method was successfully applied to the rapid and direct determination of iodide in powdered milk and thiocyanate in human saliva without any pre-concentration. The modified column could be used for about 1 month (8 h operation per day) without loss of hexadimethrine bromide.     

Determination of monovalent inorganic anions in high-ionic-strength samples by electrostatic ion chromatography with suppressed conductometric detection

A new ion chromatographic (IC) system has been established by using micelles of 3-(N,N-dimethylmyristylammonio)propanesulfonate (Zwittergent 3-14) loaded onto a reversed-phase packed column as the separation column with an electronic rotary switching valve packed-bed suppressor for conductometric detection of inorganic anions. An aqueous H3BO3-Na2B4O7 solution has been demonstrated to be the most desirable eluent for this IC system. The relationship between retention time and the concentration of the borate eluent was determined for a series of model anionic analytes and this relationship was found to be opposite to that exhibited in a conventional anion-exchange IC system. The rapid elution and complete separation of monovalent inorganic anions were obtained by initially using a high-concentration borate solution as the eluent for a short-period, and then switching to a lower-concentration borate eluent to complete the separation. Detection limits for nitrite, bromide, nitrate, and chlorate were 0.85, 0.88, 0.95 and 4.8 microM, respectively, when a 7.0 mM Na2B4O7 eluent was used. Moreover, the ability to directly detect these monovalent anions in samples containing high concentrations of sulfate and/or chloride ions provided a major advantage of this approach.     

Separation of inorganic anions on a high capacity porous polymeric monolithic column and application to direct determination of anions in seawater

A commercially available 4.6 mm id x 50 mm polymethacrylate-based monolithic strong anion exchange column (ProSwift SAX-1S) designed for the separation of proteins has been successfully used to separate small inorganic anions in the presence of a seawater sample matrix. Using a hydroxide eluent with suppressed conductivity detection the ion exchange capacity of this column declined over time; however, using KCl as the eluent, the column performance was stable with a capacity of 530 microequiv. for nitrate. The optimum conditions for the separation of iodate, bromate, nitrite, bromide and nitrate were assessed by constructing van Deemter plots using 1.00 and 0.100 M KCl. Efficiencies of up to 26 700 plates/m were recorded using 1.00 M KCl, at a flow rate of 0.20 mL/min but iodate was not baseline resolved from the void peak. By reducing the concentration of the eluent to 0.100 M, efficiencies of up to 39 900 plates/m could be obtained at 0.35 mL/min. By employing a linear gradient ranging from 0.05 to 1.00 M KCl the ions dissolved in distilled water or a salt water matrix could be baseline separated in less than 3 min at a flow rate of 2.50 mL/min.     

Determination of ceftriaxone, a novel cephalosporin, in plasma, urine and saliva by high-performance liquid chromatography on an NH2 bonded-phase column

A high-performance liquid chromatographic method has been developed for the determination of a new cephalosporin antibiotic in plasma, urine and saliva (mixed saliva) using normal-phase technique and an NH2 bonded-phase column. The eluent mixture was a combination of acetonitrile and an aqueous solution of ammonium carbonate. The rapid method involved precipitation of protein from fluids by means of acetonitrile followed by automatic injection of the supernatant. The detection limit was 0.4 micrograms/ml for plasma, 3 micrograms/ml for urine and 0.03 micrograms/ml for saliva using UV detection.     

安培检测-离子色谱法测定乳品中的微量碘

 用安培检测 离子色谱法检测了乳品中的微量碘。以NaOH作淋洗液 ,直接进样 ,优化了碘的离子色谱分离和测定条件 ,方法的检测限达 1μg/L(3倍信噪比 )。测定了婴儿奶粉、孕产妇专用奶粉和鲜牛奶中的微量碘 ,加标回收率分别为 89 0 % ,86 0 %和 84 1%。