Determination of trace level perchlorate in drinking water and ground water by ion chromatography

Ammonium perchlorate, a key ingredient in solid rocket propellants, has recently been found in ground and surface waters in the USA in a number of states, including California, Nevada, Utah, and West Virginia. Perchlorate poses a health risk and preliminary data from the US Environmental Protection Agency reports that exposure to less than 4–18 μg/l provides adequate human health protection. An ion chromatographic method was developed for the determination of low μg/l levels of perchlorate in drinking and ground waters based on a Dionex IonPac AS11 column, a 100 mM hydroxide eluent, large loop (1000 μl) injection, and suppressed conductivity detection. The method is free of interferences from common anions, linear in the range of 2.5–100 μg/l, and quantitative recoveries were obtained for low μg/l levels of perchlorate in spiked drinking and ground water samples. The method detection limit of 0.3 μg/l permits quantification of perchlorate below the levels which ensure adequate health protection. A new polarizable anion analysis column, the IonPac AS16, and its potential applicability for this analysis is also discussed.     

Simultaneous determination of trace level bromate and chlorinated haloacetic acids in bottled drinking water by ion chromatography

A convenient and sensitive method for the simultaneous determination of trace level of bromate and chlorinated haloacetic acids in bottled drinking water with ion chromatography is presented. With a high capacity anion-exchange column and 11.5 mmol/l Na₂CO₃ eluent, all the 16 analytes could be separated in one injection within 31 min. By employing a microwave based evaporation technique, the bottled drinking water sample could be concentrated tenfold in 10 min. The recoveries of the compounds ranged from 90.6 to 107.2%. With a 500 μl large volume injection and high performance anion Atlas electrolytic suppressor, the detection limits were 0.06, 0.08, 0.06, 0.14 and 0.85 μg/l for BrO₃⁻, ClO₃⁻, monoacetic acid, dichloroacetic acid and trichloroacetic acid, respectively.     

Determination of trace level bromate and perchlorate in drinking water by ion chromatography with an evaporative preconcentration technique

A simple sample preconcentration technique employing microwave-based evaporation for the determination of trace level bromate and perchlorate in drinking water with ion chromatography is presented. With a hydrophilic anion-exchange column and a sodium hydroxide eluent in linear gradient, bromate and perchlorate can be determined in one injection within 35 min. Prior to ion chromatographic analysis, the drinking water sample was treated with an OnGuard-Ag cartridge to remove the superfluous chloride and concentrated 20-fold using a PTFE beaker in a domestic microwave oven for 15 min.The recoveries of the anions ranged from 94.6% for NO2- to 105.2% for F-. The detection limits for bromate, perchlorate, iodate and chlorate were 0.1, 0.2, 0.1 and 0.2 microg/l, respectively. The developed method is applicable for the quantitation of bromate and perchlorate in drinking water samples.     

Determination of trace-level haloacetic acids in drinking water by ion chromatography-inductively coupled plasma mass spectrometry

A new method for the determination of nine haloacetic acids (HAAs) with ion chromatography (IC) coupled to inductively coupled plasma mass spectrometry (ICP-MS) was developed. With the very hydrophilic anion-exchange column and steep gradient of sodium hydroxide, the nine HAAs could be well separated in 15 min. After suppression with an ASRS suppressor that was introduced in between IC and ICP-MS, the background was much decreased, the interference caused by sodium ion present in eluent was removed, and the sensitivities of HAAs were greatly improved. The chlorinated and brominated HAAs could be detected as 35ClO and 79Br without interference of the matrix due to the elemental selective ICP-MS. The detection limits for mono-, di-, trichloroacetic acids were between 15.6 and 23.6 microg/l. For the other six bromine-containing HAAs, the detection limits were between 0.34 and 0.99 microg/l. With the pretreatment of OnGuard Ag cartridge to remove high concentration of chloride in sample, the developed method could be applied to the determination of HAAs in many drinking water matrices.     

Determination of perchlorate in drinking water by ion chromatography using macrocycle-based concentration and separation methods

Macrocycle-based ion chromatography provides a convenient, reliable method for the determination of perchlorate ion, which is currently of great interest to the environmental community. This study shows that effective perchlorate determinations can be made using standard conductimetric detection by combining an 18-crown-6-based mobile phase with an underivatized reversed-phase mobile phase ion chromatography (MPIC) column. One unique feature of this method is the flexibility in column capacity that is achieved through simple variations in eluent concentrations of 18-crown-6 and KOH, facilitating the separation of target analyte anions such as perchlorate. Using a standard anion exchange column as concentrator makes possible the determination of perchlorate as low as 0.2 ug/L in low ionic strength matrices. Determination of perchlorate at the sub-ug/L level in pure water and in spiked local city hard water samples with high background ion concentrations can be achieved this way. However, like other IC techniques, this method is challenged to achieve analyses at the ug/L level in the demanding high ionic strength matrix described by the United States Environmental Protection Agency (EPA) (1,000 mg/L chloride, sulfate and carbonate). We approached this challenge by use of the Cryptand C1 concentrator column, provided by Dionex Corporation, to effectively preconcentrate perchlorate while reducing background ion concentrations in the high ionic strength matrix. The retention characteristics of the concentrator column were studied in order to maximize its effectiveness for perchlorate determinations. The method makes possible the determination of perchlorate at the 5 ug/L level in the highest ionic strength matrix described by the EPA.     

Determination of haloacetic acids in water by ion chromatography--method development.

The microextraction/ion chromatographic (IC) method developed in this study involves extraction of 9 haloacetic acids (HAAs) from aqueous samples (acidified with sulfuric acid to a pH of < 0.5 and amended with copper sulfate pentahydrate and sodium sulfate) with methyl tert-butyl ether (MTBE), back extraction into reagent water, and analysis by IC with conductivity detection. The separation column consists of an Ion Pac AG-11 (2 mm id x 50 mm length) guard column and an Ion Pac AS-11 (2 mm id x 250 mm length) analytical column, and the concentration column is a 4 mm id x 35 mm length Dionex TAC-LP column. Use of the 2 mm id Dionex AS-11 column improved detection limits especially for trichloracetic acid (TCAA), bromodichloroacetic acid (BDCAA), dibromochloroacetic acid (DBCAA), and tribromoacetic acid (TBAA). The peak interfering with BCAA elutes at the same retention time as nitrate; however, we have not confirmed the presence of nitrate. Stability studies indicate that HAAs are stable in water for at least 8 days when preserved with ammonium chloride at 100 mg/L and stored at 4 degrees C in the dark. At day 30, recoveries were still high (e.g., 92.1-106%) for dichloroacetic acid (DCAA), BCAA, dibromoacetic acid (DBAA), trichloroacetic acid (TCAA), BDCAA, and DBCAA. However, recoveries of monochloroacetic acid (MCAA), monobromoacetic acid (MBAA), and TBAA were only 54.6, 56.8, and 66.8%, respectively. Stability studies of HAAs in H2SO4-saturated MTBE indicate that all compounds except TBAA are stable for 48 h when stored at 4 degrees C in the dark. TBAA recoveries dropped to 47.1% after 6 h of storage and no TBAA was detected after 48 h of storage. The method described here is only preliminary and was tested in only one laboratory. Additional research is needed to improve method performance.     

Preconcentration and separation of haloacetic acids by ion chromatography

A comparative study was made of the chromatographic behaviour of five haloacetic acids (mono-, dibromoacetic and mono-, di-, trichloroacetic acids). The techniques investigated included reversed-phase ion interaction chromatography with UV detection, suppressed and non-suppressed anion-exchange chromatography. The systems are discussed studying the retention as a function of the mobile phase parameters and the stationary phases used (LiChrospher 100 RP-18, IonPac AS9, AS10 and AS11). A preconcentration step, performed on different substrates, namely LiChrolut-EN and activated vegetal carbon, has been optimized in order to reduce the method detection limits. Results obtained for drinking water samples are shown.     

Determination of perchlorate at parts-per-billion levels in plants by ion chromatography

A method for the analysis of perchlorate in plants was developed, based on dry weight, and applied to the analysis of plant organs, foodstuffs, and plant products. The method reduced greatly the ionic interferences in water extracts of plant materials. The high background conductivity, due to the plant matrix, was reduced sufficiently to allow quantitation of perchlorate with little or no matrix interference. Ion chromatography (IC) on a microbore AS16 anion-exchange column and a conductivity detector was used for separation and detection of perchlorate from the ionic plant extract. The extract was heated to precipitate proteins, centrifuged, exposed to alumina, and filtered through a cartridge filled with divinylbenzene to yield a water clear extract for IC analysis, even from highly colored solutions. Heating the extract and treatment with alumina reduced substantially the ionic content of the extracts without loss of perchlorate.     

Improved method for the determination of trace perchlorate in ground and drinking waters by ion chromatography

Ammonium perchlorate, a key ingredient in solid rocket propellants, has been found in ground and surface waters in a number of U.S. states, and perchlorate contamination of public drinking water wells is now a serious problem in California. Perchlorate poses a health risk and preliminary data from the U.S. EPA reports that exposure to less than 4-18 microg/l provides adequate human health protection. An improved ion chromatographic method was developed for the determination of low microg/l levels of perchlorate in ground and drinking waters based on a Dionex IonPac AS16 column, an hydroxide eluent generated using an EG40 automated eluent generator, large loop (1000 microl) injection, and suppressed conductivity detection. The method is free of interferences from common inorganic anions, linear over the range of 2-100 microg/l perchlorate, and quantitative recoveries are obtained for low microg/l levels of perchlorate in spiked ground and drinking water samples. The MDL of 150 ng/l permits quantification of perchlorate below the levels that ensure adequate health protection.     

Use of temperature programming to improve resolution of inorganic anions, haloacetic acids and oxyhalides in drinking water by suppressed ion chromatography

Temperature programming was used to improve selectivity in the suppressed ion chromatographic (IC) separation of inorganic anions, haloacetic acids and oxyhalides in drinking water samples when using NaOH gradient elution. The programme exploited varying responses of these anions to changes in temperature. Heats of adsorption (deltaH, kJ/mol) for 17 anionic species were calculated from van't Hoff plots. For haloacetic acids, both the degree of substitution and log P (log of n-octanol-waterpartition coefficient) values correlated well with the magnitude of the temperature effect, with monochloro- and monobromoacetic acids showing the largest effect (deltaH= -10.4 to -10.7 kJ/mol), dichloro- and dibromoacetic acids showing a reduced effect (deltaH= -6.8 to -8.4 kJ/mol) and trichloro-, bromodichloro- and chlorodibromoacetic acids showing the least effect (deltaH= -4.7 to -2.4 kJ/mol). The effect of temperature on oxyhalides ranged from deltaH= 8.4 kJ/mol for perchlorate to deltaH= -9.1 kJ/mol for iodate. The effectiveness of two commercial column ovens was investigated for the application of temperature gradients during chromatographic runs, with the best system applied to improve the resolution of closely retained species at the start, middle and end of the separation obtained using a previously optimised hydroxide gradient, in a real drinking water sample matrix. Retention time reproducibility of the final method ranged from 0.62 to 3.18% RSD (n = 30) showing temperature programming is indeed a practically important parameter to manipulate resolution.     

Determination of inorganic ions in drinking water by ion chromatography

Ion chromatography (IC) is now a well established methodology for the analysis of ionic species. The technique is applicable to the determination of a wide range of solutes in many sample types, although the determination of inorganic ions in drinking water continues to be the most widely used application of ion chromatography. Many regulatory and standard organizations, such as ASTM, AOAC, ISO, and US EPA, have approved methods of analysis based upon IC, most of which have been published within the last 10 years. Recent developments in the field of IC, such as the use of higher capacity columns, larger loop injections, more complex sample preparation and detection schemes, have been incorporated into new approved methods to allow the determination of inorganic contaminants, such as bromate, perchlorate, and chromate, at low μg/l levels in drinking waters. IC appears certain to remain an important technique for drinking water analysis and new methods based on IC will continue to be developed as more inorganic contaminants become regulated at lower limits in the future.     

Determination of trace anions in concentrated weak acids by ion chromatography

Ion-exclusion chromatography (ICE) followed by ion chromatography (IC) was used for the determination of trace anionic contaminants in concentrated weak acids. The ICE separation was used as a pretreatment step to isolate the contaminant anions of strong acids from the excess of matrix ions. Then a fraction containing the analyte ions was separated using IC with suppressed conductivity detection. Microbore–ion-exchange columns were chosen to address the increased purity requirements for use of these concentrated acids in semiconductor applications. The chromatographic conditions were optimized for determining trace chloride, sulfate, phosphate, and nitrate in concentrated 24.5% (v/v) hydrofluoric acid; trace chloride, sulfate, and nitrate in concentrated 85% (w/w) phosphoric acid and trace chloride and sulfate in concentrated 0.7% (v/v) glycolic acid. Method detection limits for the anions of interest were below 100 μg/l.     

盐析微萃取-气相色谱法测定饮用水中痕量甲苯

采用正丁醇为萃取剂,硫酸铵为盐析剂,建立了盐析微萃取-气相色谱法测定饮用水中痕量甲苯的分析方法,并对影响相分离的各种条件进行了优化。当水相体积为10m L,萃取剂正丁醇为300μL,盐析剂硫酸铵为4.5g,萃取时间为10min时,甲苯在0.01~0.50mg·L-1和0.50~25.00mg·L-1浓度范围内与峰面积呈线性关系,相关系数分别为0.99987和0.99982,方法的检出限为0.002mg·L-1,对于质量浓度为0.50mg·L-1的甲苯进行7次反复测量,得到其相对标准偏差为4.3%。该方法用于饮用自来水和河水中痕量甲苯的测定,平均回收率分别为91.59%和92.17%。     

离子色谱法测定葡萄酒中的高氯酸盐

建立了离子色谱测定红酒中高氯酸盐的分析方法。以4种葡萄酒为典型样品,测定了其中的高氯酸盐含量。使用Metrosep A Supp5阴离子分析柱（150 mm×4.0 mm）进行分离,柱温为40℃,流动相为1.0 mmol/L碳酸钠水溶液-丙酮（85：15,v/v）,流速为0.8 mL/min。结果表明,高氯酸盐在0.1~10 mg/L内具有良好的线性关系,相关系数为0.9998,方法回收率大于86.0%,相对标准偏差小于2.6%。该方法前处理方便快捷、检测灵敏度高,可满足红酒中高氯酸盐含量的测定。     

离子色谱-质谱联用技术测定饮用水及环境水样中的痕量高氯酸盐

建立了一种测定痕量高氯酸盐的离子色谱-质谱联用方法.选用高容量、强亲水性的阴离子交换柱IonPac AS20(2 mm)进行分离,以淋洗液自动发生器在线产生的KOH为淋洗液,采用等浓度淋洗.在不添加有机溶剂的情况下,淋洗液经过抑制器抑制后直接进入电喷雾-串联质谱(ESI-MS-MS),以负离子模式进行检测.同时采用多元反应监测(MRM)模式对高氯酸盐进行监控,以100.8/84.9、 98.8/66.9和100.8/68.9为监控离子对,以98.8/82.9离子对的峰面积进行定量.高氯酸盐质量浓度在0.05～50 μg/L范围内具有良好的线性(r＝0.9985),检出限(S/N=3)为0.01 μg/L.将该方法用于饮用水以及地下水、雪水等环境水样中高氯酸盐的分析,并进行了加标回收实验,回收率在86%～110%之间,将实际自来水样品连续11次进样,所得高氯酸盐的峰面积的相对标准偏差(RSD)为1.6%.     

Determination of sulfonic acids and alkylsulfates by ion chromatography in water

A fast ion chromatographic method with suppressed conductivity detection has been developed for the simultaneous determination of methane-, ethane-, 1-propane-, 1-butane-, 1-pentane-, 1-hexane-, 1-heptane-, 1-octane-, 1-nonane-, 1-decane-, 1-dodecane-, dodecylbenzene-, p-toluene-, benzenesulfonic acids, octylsulfate and dodecylsulfate in water samples. Due to the high number of analytes and their heterogeneity, the effect of the mobile phase parameters (NaOH, CH(3)OH and CH(3)CN concentration) on the retention factors has been studied in detail, so achieving, for the first time, the separation among 15 of these analytes by a gradient elution. Detection limits included within 0.06-0.16 microM have been obtained. Interferences from Cl(-), NO(3)(-) and SO(4)(2-), possible anions present in water samples, have been considered and a SPE procedure has been developed for analytes enrichment and matrix removal in a seawater sample. This is the first application of an ion-exchange chromatographic method to a seawater sample for this kind of analytes.     

Determination of sulphide ion at trace levels by ethylation and gas chromatography

Summary A method is described for the determination of sulphide ion in aqueous samples by gas chromatography. Sulphide is ethylated with diethyl sulphate and the resulting diethyl sulphide is extracted with chloroform and determined with a gas chromatograph equipped with a flame ionization or a flame photometric detector. In the case of a flame photometric detector, the detection limit for sulphide ion is 0.05 g/ml. Other anions commonly found with sulphide ion do not interfere. Sulphide ion in spring waters was analysed by this new method and for comparison also by colorimetry (methylene blue). The results revealed the reliability of the new method.

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Bestimmung von Sulfidspuren durch Ethylierung und Gas-Chromatographie

Zusammenfassung Sulfid wird mit Diethylsulfat ethyliert, das gebildete Diethylsulfid mit Chloroform extrahiert und gaschromatographisch mit Hilfe eines Flammenionisationsoder eines flammenphotometrischen Detektors bestimmt. Die Nachweisgrenze beträgt 0,05 g S/ml für den FPD. Anionen, die üblicherweise mit Sulfid zusammen vorkommen, stören nicht. Das Verfahren wurde, im Vergleich mit der colorimetrischen Methylenblaumethode, auf Quellwasser angewendet. Es wurde gute Übereinstimmung der Ergebnisse erzielt.

     

二维离子色谱法同时测定环境水样中的碘离子、硫氰酸根和高氯酸根

建立了二维离子色谱法同时测定环境水样中的碘离子、硫氰酸根离子和高氯酸根离子的方法。先采用常规阴离子色谱柱(IonPac AS16, 250 mm×4 mm)将水样中的碘离子、硫氰酸根离子和高氯酸根离子与干扰离子进行分离。样品溶液通过抑制器后,将含有碘离子、硫氰酸根离子和高氯酸根离子的淋洗液导入富集柱(MAC-200, 80 mm×0.75 mm),再通过毛细管阴离子色谱柱(IonPac AS20 Capillary, 250 mm×0.4 mm)进行分离和定量分析。方法的线性范围为0.05～100 μg/L,相关系数达到0.9999,检出限为0.02～0.05 μg/L。样品中碘离子、硫氰酸根离子和高氯酸根离子的加标回收率在85.1%～100.1%之间,回收率的相对标准偏差(RSD)(n=6)在1.7%～4.9%之间。该法试剂用量小,灵敏度比常规离子色谱提高30～40倍,同时去除了样液中的高浓度基体杂质,适用于水样中低含量碘离子、硫氰酸根离子和高氯酸根离子的检测。     

Determination of bromate ion in drinking water by capillary zone electrophoresis with direct photometric detection

Bromate ion in drinking water was determined by capillary zone electrophoresis (CZE) with direct photometric detection. Bromate ion in the sample solution was introduced and concentrated into the capillary by electrokinetic injection for 50s at -10 kV. Electrophoretic separation was made at an applied voltage of -25 kV and bromate ion was detected at wavelength 193 nm, at which the baseline was stabilized with less UV-absorbing acidic phosphate buffer. Bromate ion was detected within 5 min in the electropherogram. By increasing the electric conductivity in the migrating solution with 10 mM Na2SO4, a limit of detection (LOD) of 9 x 10(-10)M (0.1 microg/L BrO3-) was achieved. The proposed method was applied to the analysis of tap water and river water samples, but bromate ion was not detected. Because the practical samples contain relatively large amount of foreign ionic substances, the tap water sample was diluted to avoid the matrix ions. Bromate ion added in a tap water at the concentration of 8 x 10(-8)M was quantitatively recovered by diluting it 1/10.     

固相萃取-离子色谱法测定地下水中痕量高氯酸根离子

建立了测定地下水中痕量高氯酸根（ClO~4）的固相萃取-离子色谱(SPE-IC)分析方法。0.7 L水样经预处理降低主要干扰离子Cl~、CO2~3和SO2~4的干扰后,使用Cleanert PWAX弱阴离子交换固相萃取小柱对地下水中痕量(μg/L级)的ClO~4进行富集,用6 mL 1%NaOH溶液洗脱,富集液经0.45 μm水膜过滤后,用IonPac AS20阴离子分离柱、50 μL进样环、40 mmol/L KOH溶液淋洗、抑制电导检测分离分析。结果表明,地下水样品中ClO~4的方法检出限和测定下限分别为0.15 μg/L和0.60 μg/L,进样质量浓度在1～15 μg/L范围内有很好的线性关系,线性相关系数为0.9992,回收率为99.7%～100.5%;该方法经济有效,可用于地下水中痕量ClO~4的检测。利用该方法测定了哈尔滨周边部分地区地下水中ClO~4浓度,检测结果与离子色谱-质谱联用法的检测结果的相对误差为1.85%～9.24%。