Quantification of inorganic anions in surface and drinking waters using ion chromatography

Sicilian bottled natural waters: Major and trace inorganic components

Nitroaromatic compounds are used extensively in various fields such as dyes, pesticides, spices, pharmaceuticals, and explosives. However, the residual raw materials of these compounds accumulate in the environment and pose serious risks to human health. Chronic exposure to low concentrations of nitroaromatic compounds can cause anemia, cancer, and organ damage. Currently, Fenton oxidation and natural bioremediation are the processes most often used to eliminate nitroaromatic compounds from environmental water and soil. According to previous research, the presence of inorganic anions such as chloride, nitrite, and nitrate ions in the environmental matrix exerts an inhibitory effect on the biodegradation of nitroaromatic compounds. Furthermore, high nitrate levels in drinking water can lead to the production of nitrosamine carcinogens, which affect ecological safety and human health, in water bodies. Thus, the simultaneous determination of nitroaromatic compounds and chloride, nitrite, and nitrate ions in environmental soil and water matrices is critical for selecting appropriate nitroaromatic compound degradation methods and monitoring surface water quality. Traditional detection methods require two sample pretreatment steps and two instrumental analytical techniques to determine nitroaromatic compounds and inorganic anions in environmental matrices; moreover, these methods are time consuming, labor intensive, and error prone. Therefore, in this study, a method that combines high performance liquid chromatography (HPLC) and ion chromatography (IC) was developed to simultaneously detect nitroaromatic compounds and anions in environmental matrices. In this method, sample enrichment was achieved through bulk injection and enrichment column collection, which greatly simplified the pretreatment process. The HPLC instrument was connected to the IC instrument using two six-way valves and an enrichment column. The system operation can be divided into four stages: (A) sample loading to the quantitative ring, (B) separation of nitroaromatic compounds and anions, (C) enrichment of anions in an AG20 column, and (D) simultaneous determination of nitroaromatic compounds and anions by HPLC and IC, respectively. The time of the anions flowing out of the C18 column was determined by directly connecting the C18 column to a conductivity detector. Based on the retention times of the anions, the switching time of the six-way valve was optimized to ensure that the anions completely entered the IC column, thereby ensuring the accuracy of the method. During the chromatographic analysis stage, nitroaromatic compounds were separated and analyzed by HPLC system with a mobile phase composed of potassium phosphate buffer (pH 7.0) and acetonitrile (60∶40, v/v) at a flow rate of 1.0 mL/min; in the IC system, the anions were separated and analyzed using a 20 mmol/L sodium hydroxide aqueous solution as the mobile phase under a suppression current of 50 mA. Both anions and nitroaromatic compounds exhibited strong linear correlations within certain concentration ranges, with correlation coefficients greater than 0.993. The recoveries of the nitroaromatic compounds and anions ranged from 88.20% to 105.38% at three spiked levels, with relative standard deviations ranging from 2.0% to 11.5%. The contents of six nitroaromatic compounds and three anions in five surface water and five soil samples were determined using the developed method. Although no nitroaromatic compounds were detected in these samples, the three anions were detected at contents ranging from 0.41 to 55.3 mg/L in surface water samples, and 0.56 to 30.2 mg/kg in soil samples. Methodological validation and actual sample detection demonstrated that the proposed method has a high degree of automation, simple operation, good repeatability, high accuracy, wide applicability, and high sensitivity. Thus, this method is suitable for the rapid determination of chloride, nitrite, nitrate ions and nitroaromatic compounds in soil and water and can be extended to the simultaneous determination of inorganic ions and organic matters in other samples.

Perchlorate has been identified in ground and surface waters around the USA including some that serve as supplies for drinking water. Because perchlorate salts are used as solid oxidants in rockets and ordnance, water contamination may occur near military or aerospace installations or defense industry manufacturing facilities. This ion has been added to the Environmental Protection Agency's Contaminant Candidate List and the Unregulated Contaminant Monitoring Rule. Concern over perchlorate has prompted many residents in affected areas to switch to bottled water; however, bottled waters have not previously been examined for perchlorate contamination. Should the EPA promulgate a regulation for municipal water systems, US law requires the Food and Drug Administration to take action on bottled water. Methods will therefore be required to determine perchlorate concentrations not only in tap water, but also in bottled waters. Ion chromatography (IC) is the primary technique used for its analysis in drinking water, but it does not provide a unique identification. Confirmation by electrospray ionization mass spectrometry (ESI-MS) can serve in this capacity. The ESI-MS method can be applied to these products, but it requires an understanding of matrix effects, especially of high ionic strength that can suppress electrospray. When using methyl isobutyl ketone (MIBK) as the extraction solvent, the ESI-MS method can reach lower limits of detection of 6 ng ml −1 for some bottled waters. However, dilution required to negate ionic strength effects in mineral waters can raise this by a factor of 10 or more, depending on the sample. Decyltrimethylammonium cation (added as the bromide salt) is used to produce an ion pair that is extracted into MIBK. After extraction, the sum of the peak areas of the ions C10H21NMe3(Br)(ClO4)− (m/z = 380) and C10H21NMe3(ClO4)2− (m/z = 400) is used to quantitate perchlorate. Standard additions are used to account for most of the matrix effects. In this work, eight domestic brands and eight imported brands of bottled water were comparatively analyzed by the two techniques. For comparison, a finished potable water known to contain perchlorate was also tested. None of the bottled waters were found to contain any perchlorate within the lower limit of detection for the IC method. Recoveries on spiked samples subjected to the IC method were ≥98%. Published in 2000 for SCI by John Wiley & Sons, Ltd

O-31C6-1 Background/Aims: Interview data from the National Birth Defects Prevention Study identified 42% of Texas participants drinking bottled water exclusively at the beginning of pregnancy. Little information is available on the nitrate content of bottled water. Substantial numbers of low-income Mexican American women along the Texas/Mexico border reside in marginalized areas called colonias. Common concerns related to these areas are persistent poverty, lack of infrastructure, neighborhood deprivation, and uncertain water sources. In addition to bottled water purchased in grocery stores, the border population also buys water from maquinas de aqua (water machine or water kiosks), which may be subject to little or no regulation of water quality. The objective of this study was to collect samples of bottled water and water from maquinas de aqua in order to determine nitrate level. Methods: Using 3- to 5-mile buffers around addresses, neighborhoods along the 800-mile Texas-Mexico from Brownsville to El Paso, where the National Birth Defects Prevention Study participants resided, were identified. Trained promotora and researcher surveyed all traditional, convenience, and nontraditional food stores for bottled water; maquinas de aqua were identified; and 100 samples of bottled and water mill water were collected. Water samples were transported to the University of Iowa Hygienic Laboratory (UHL) for testing. UHL will utilize EPA Method 300.0, Inorganic Anions by Ion Chromatography, Rev 2.1 in Methods for the Determination of Inorganic Substances in Environmental Samples (EPA/600/R-93/100). Results: A total of 195 food stores (supercenters, supermarkets, grocery stores, convenience stores, and dollar stores) and 113 maquinas de aqua were identified. Samples were collected from more than 75 locations. Nitrate levels varied by geographic locale and type of water. Conclusion: Considering the growth of water machines and greater reliance by marginalized communities on water from other than tap, it is no longer appropriate to use nitrate content of tap water as singular proxy for nitrate exposure from water.

An ion chromatography (IC) have been developed for the simultaneous determination of inorganic cations (Na+, NH4+, K+, Mg2+, and Ca2+) and inorganic anions (PO43−, Cl−, NO3−, and SCN−) using a single pump, a single eluent and a single detector. The method is based on column switching means allows anions and/or cations could be determined in a single analysis system. While one ion-exchange column is being operated, the other ion-exchange column is being conditioned, i.e., the columns are always ready for analysis at any time. When the combination of 10 mM tartaric acid was used as the eluent, and operated at eluent flow rate of 0.5 mL/min, five cations and four anions could be separated on the cation-exchange column and the anion-exchange column, respectively. The separation of cations was completed within 15 min, whereas the separation of anions was completed within 40 min. The detection limits was calculated at S/N = 3 were 3.10–12.14 ppb (µg/L) for the cations and 16.00–88.10 ppb for the anions. The relative standard deviations of the all ions were less than 4.81%, 6.30%, and 6.22% for peak height, peak area, and retention time, respectively. The developed technique was successfully applied to the simultaneous determination of inorganic cations and anions in human saliva and urine samples.

Determination of Heavy Metals, Nitrate and Nitrite in Mineral and Drinking Bottled Water in Tehran, Iran: a Health Risk Assessment by Monte-Carlo Simulation Method

For this study, bromide and bromate ions in various commercial brands of Indian bottled water samples were estimated using ion chromatography. The measured mean concentration of bromide and bromate ions in water samples was found to be 28.13 µg/L and 11.17 µg/L respectively. The average level of bromate in Indian bottled water was found to be slightly higher (~ 12%) than the acceptable limits (10 µg/L) recommended by USEPA (US Environmental Protection Agency). Though, kinetically, it is predicted that 62.5% (6.25 µg/L) of bromide in bottled water is needed to convert into bromate upon ozonation to exceed the minimum acceptable limits, but the average formation of bromate determined to be only 26.77% of the predicted concentration. Bromate concentration in bottled water showed a strong correlation with bromide suggesting that its formation in water is very much influenced and controlled by bromide content. The objective of the present study was to determine the BrO3–) content of commercially available different brands of bottled drinking water in India and to estimate the health risks to population due to ingestion. Results of estimated excess cancer risk and chemical toxicity risk to Indian population due to ingestion of bottled water were presented and discussed.

Perchlorate is a potent thyroid hormone-disrupting compound. Drinking water is one of the major sources of human exposure to perchlorate. Little is known about the occurrence of perchlorate in waters from China. In this study, water samples (n = 300) collected from 15 locations in 13 provinces and municipalities were analyzed for the presence of perchlorate. In addition, other inorganic anions that commonly occur in water--iodide, bromide, and nitrate--and the disinfection byproducts, bromate, chlorate, and chlorite were determined by high-performance liquid chromatography interfaced with tandem mass spectrometry. Perchlorate was detected in 86% of the samples analyzed, at concentrations ranging from <0.02 to 54.4 microg l(-1) (mean +/- SD 2.20 +/- 6.39 microg l(-1); median 0.62 microg l(-1)). Mean concentrations of perchlorate in tap water, groundwater, surface waters, and bottled water were 2.46, 3.04, 2.82, and 0.22 microg l(-1), respectively. Significant positive correlations were found between the concentrations of perchlorate and nitrate, perchlorate and chlorate, bromide and iodide, and nitrate and iodide.

Separation of anions by ion chromatography–capillary electrophoresis

Comparison of liquid chromatographic behaviors on N-methylimidazolium functionalized ZrO 2/SiO 2-4 and N-methylimidazolium functionalized SiO 2 stationary phases

A single reversed-phase ODS (octadecyl silica) column coated with taurine-conjugated bile salt micelles has been investigated for simultaneous separation of inorganic cations and anions. Under acidic conditions in the separation column, taurine-conjugated bile salts are protonated; therefore, the stationary phase coated with taurine-conjugated bile micelles exists as a "weak/strong"-charged zwitterionic stationary phase (H+ and SO3-). The weak/strong-charged zwitterionic stationary phase provides a new retention mechanism which is different from conventional ion chromatography in that both positive and negative charges are close together in a single molecule, resulting in simultaneous electrostatic attraction and repulsion of the analyte ions. Also, the stronger negative charge (sulfonate) of the stationary phase works as a cation-exchange site at the same time. The combined effects of cation-exchange and simultaneous electrostatic repulsion/attraction interactions were successfully used in ion chromatography for the simultaneous separation of inorganic cations and anions.

Simultaneous separation of inorganic anions and cations by using anion-exchange and cation-exchange columns connected in tandem in ion chromatography

Chemical Evaluation of Commercial Bottled Drinking Water from Egypt

The ion-exchange and complex forming equilibria were quantitatively described and demonstrated in order to understand major factors in the control of selectivity in the analytical separation of carboxylic acids and inorganic anions in cryptand based ion chromatography. A complex retention model has been developed for the separation on a non-conventional IC column. Changes in retention are treated both theoretically and experimentally. Retention mechanism is employed on a macrocycle-based (cryptand n-decyl-[2.2.2]) ion-exchange chromatographic phase to improve the selectivity for a mixture of model analytes. We introduced an alternative internal gradient method by mixed eluent (i.e. eluents formed by combination of two alkali hydroxide with different molar ratio). The effect of binary mixed eluent (Li/Na, Li/K) on the retention behavior and peak shape of carboxylic acids are also discussed in view of the proposed theory. It was shown that the effects of binary aqueous mobile phases, held isocratically behave very similar to the step gradient mode. The "internal gradient” separation system has advantages over traditional step gradient mode. Twenty-six anions of widely varying chemical character (mono-, di-, tri-valent inorganic anions, mono-, di-, tri-valent aliphatic carboxylic acids, aromatic- and haloacetic carboxylic acids) were investigated on the cryptand-based (D222) stationary phase using different methods by LiOH, NaOH and KOH eluent. The predicted vs measured retention data are in rather good agreement. High degree of linearity was obtained for inorganic anions, multivalent carboxylic acids, and for aromatic and haloacetic acids R2 = 0.992, 0.969, and 0.980, respectively.

Bottled water is most well liked within the world and attention is drawn due to its health issues. Oxyhalides is one amongst the foremost important by-products in bottled water which is produced by disinfection process such as "ozonation". International standards have been set and justified to permissible levels for chlorate, chlorite and bromate as 700, 700 and 10μg/l. Thereafter, 168 samples of bottled water (mineral and drinking water) from Iran market obtained with the optimal working conditions and analyzed by ion chromatography (IC) with conductivity detector. The results actuated that 23 and 17 out of 168 samples as mineral and drinking water revealed bromate content in charge of the national permissible level, found as the mean level of 37.04 and 33.58μg/l, respectively. According to risk assessment results, the average of hazard quotient (HQ) and lifetime excess cancer (ELCR) were calculated 6.955 × 10-3 and 0.25 × 10-3, respectively. Thereupon, it is indispensable to control as well as make consumers aware of oxyholides hazard especially bromate following governmental authorities with an insight to health sectors monitoring guidelines due to its obvious harmful effects and aspects on health issues.