Simultaneous Determination of Inorganic Anions in Bottled Drinking Water by the Ion Chromatography Method

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1 ISSN X, Journal of Water Chemistry and Technology, 2015, Vol. 37, No. 5, pp Allerton Press, Inc., Original Russian Text H. Daraei, A. Maleki, A.H. Mahvi, L. Alaei, R. Rezaee, E. Ghahremani, N. Mirzaei, 2015, published in Khimiya i Tekhnologiya Vody, 2015, Vol. 37, No. 5, pp ANALYTICAL CHEMISTRY OF WATER Simultaneous Determination of Inorganic Anions in Bottled Drinking Water by the Ion Chromatography Method H. Daraei a, A. Maleki a, *, A. H. Mahvi b, L. Alaei c, R. Rezaee a, E. Ghahremani a, and N. Mirzaei a a Kurdistan Environmental Health Research Center, Kurdistan University of Medical Sciences, Sanandaj, Iran b School of Public Health and Center for Environmental Research Medical Sciences, University of Tehran, Iran c Institute of Biochemistry and Biophysics, University of Tehran, Iran * maleki_afshin@ymail.com Received October 16, 2012 Abstract Simultaneous analysis of seven inorganic anions (fluoride, chloride, nitrite, bromide, nitrate, phosphate and sulfate-ions) was carried out in two sets of 10 brands of mineral bottled waters (Iran) using ion chromatography (IC). Waters were sampled in autumn and winter of The obtained concentrations compared with the values on the labels. It was established that concentrations of the specified ions in tested waters were within the acceptable levels of the World Health Organization (WHO) and the United States Environmental Protection Agency (USEPA). Comparison of label values with our experiments showed that 11 label values had meaningful difference from the corresponding test values. The analysis of variance (ANOVA) revealed that sampling in autumn and winter periods did not influence the content of ions in water. DOI: /S X Keywords: ion chromatography, mineral bottled water, multicomponent analysis, inorganic anions INTRODUCTION Mineral bottled drinking waters are frequently used for tap water in Iran. This is explained by the need of replenishing of our bodies with macro- and micro-elements after physical activities. At the same time mineral waters are of medicinal value that is widely used in advertisements and contributes to the rise of their popularity. Since such waters are an important source of the water consumed by people, it is necessary that bottled water should meet the same standards for anion levels and other components as the tap water [1]. The US National Primary Drinking Water Standards postulate a maximum contaminant level (MCL) for some of common inorganic anions, including fluoride, nitrite and nitrate. The MCLs are specified to minimize potential health risk effects arising from the intake of these anions in water supplies. For instance, high levels of fluoride may cause skeletal and dental fluorosis, while nitrite and nitrate can cause methaemoglobulinemia, which can be fatal to infants [2, 3]. Consequently, the analysis of these anions in drinking waters is mandated, as are the analytical methods which can be used for their quantification. Other common anions, such as chloride and sulfate, are classified as secondary contaminants. The Secondary Drinking Water Standards regulate approaches regarding taste, odor, color and certain esthetic effects which are not federally enforced. However, they are recommended to all the States as accepted goals; and many of the States adopt their own enforceable regulations governing the concentration of these contaminants [2, 3]. Traces of fluoride are present in many waters. However, higher concentrations are often associated with underground sources. In areas where fluoride-containing minerals are rich, well waters may contain up to about 10 mg of fluoride per 1 dm 3. In groundwater, fluoride concentrations vary with the type of rock that the water flows through but do not usually reach 10 mg/dm 3 [4]. In drinking water prepared from well water, fluoride concentration levels of up to 3.3 mg/dm 3 have been reported [5]. The MLC value (established in 1984) is 1.5 mg/dm 3. The nitrate MLC in drinking water is 3 mg/dm 3 (on a nitrogen basis). This is about 13.5 mg/dm 3 of NO 3. In most countries, nitrate levels in drinking water derived from the surface water do not exceed 10 mg/dm 3. However, in some areas the concentrations are higher as a result of run-off and the discharge of sewage effluent and certain industrial wastes. Because of the possibility of the simultaneous occurrence of nitrite and nitrate 253

2 254 DARAEI et al. in drinking water, the sum of the concentration ratios of each of these components to its MLC level should not exceed unity [5]. No health-based maximum admissible amounts of sulfate in drinking water were established by either WHO or USEPA. However, because of the gastrointestinal effects resulting from ingestion of drinking water containing high sulfate levels, it is recommended to notify the health authorities of sources of drinking water that contain sulfate concentrations in excess of 500 mg/dm 3 [5]. The taste threshold of the chloride anion in water is dependent on its associated cation. Taste thresholds for sodium chloride and calcium chloride in water correspond to concentrations ranging from 200 to 300 mg/dm 3. For example, the taste of coffee is affected if the coffee is made with water having a sodium chloride concentration of 400 mg/dm 3 or calcium chloride concentration of 530 mg/dm 3 [6]. No data about the health-based admissible amounts of chloride in drinking water are available in literature. In order to determine inorganic anions in drinking waters, a number of analytical methods have been used, such as capillary ion electrophoresis [7, 8] and ion chromatography [9 11]. Among these techniques ion chromatography is the most widely used and recommended by USEPA as an official method for analysis of drinking water samples in the USA [12]. Small et al. reported the first method for separation and quantitative determination of inorganic ions by high-performance liquid chromatography [13]. This technique, called ion chromatography (IC), uses a combination of analytical column and suppressor column for the purpose of decreasing the electric conductivity of the mobile phase during conductometric detection [14]. Among the methods based on ion chromatography there are two well-known and widely applied methods, namely, the suppressed and non-suppressed methods. In using the suppressed method, after the eluent has passed through the analytical column, the functional groups of which have the charge opposite to the charge of sample ions, the latter are washed out in turn from the column by eluent. The background electrical conductivity of eluent is eliminated by a special device representing suppressor column. In this case the electrical conductivity of the eluent is largely reduced, and a highly sensitive analysis of anions becomes possible [15]. EXPERIMENTAL Ten different brands of the most popular mineral bottled waters: Zamzam, Vata, Nina, Kulak, Kosalan, Koohrang, Hayat, Damavand, Aras, and Aouraman (two bottles of 500 cm 3 each for each brand and produced at different time) were used for investigations. All bottles were kept sealed and refrigerated at 5 C until the time of analysis. Mobile phase and acids used for the treatment of suppressor column together with standard samples were prepared by using water type 1 Merck (Germany). Standard concentrations of anions were prepared from stock standard solutions (purchased from Fluka Company, Switzerland). Ion chromatography was carried out using a compact ion chromatographer (882 Compact IC plus) (Metrohm Company) equipped with a conductivity detector and a 20 ìl injection loop. The separation of anions was performed on a Metrosep A Supp analytical column at 25 C with a 1 cm 3 /min flow rate of eluent. A Metrosep A Supp 4/5 Guard column and suppressor systems were also connected to the analytical columns. A mixture of sodium hydrogen carbonate (1.7 mm) and sodium carbonate (1.8 mm)) was used as a mobile phase for eluting of anions. Data acquisition and instrument settings were performed by using the Magic Net software v.2.1 (Metrohm). The ultra-pure water was used as a blank. Working standard solutions were prepared from the first solutions (Fluka) following the proper sequential dilutions. Four mixed standard solutions with concentrations of 1, 5, 25 and 50 ppm of each of four desired anions were used to plot the calibration curve. The linear relationship between the peak area and concentration was confirmed experimentally. There are several possible approaches for determining the detection and quantification limits, depending on whether the procedure is instrumental or non-instrumental. In this study we used an approach based on the mathematical processing of calibration curve. Detection limit (DL) can be expressed as follows [16]: DL = A+3S (y/x), where A represents a length from the intercept of the calibration curve with Y-axis to the origin of coordinates, and quantity S (y/x) can be expressed as follows:

3 SIMULTANEOUS DETERMINATION 255 n ( y i ŷ i ) 2 i = 0 S (y/x) = , n 2 where y i is the response of each point of calibration curve, ŷ i is a prediction of regression for same point, and n is the number of calibration standard solutions used. The results are shown in Table 1. Table 1. Detection limits of anions while using the ion chromatography 1 2 Anion Detection limit, mg/dm 3 Fluoride Chloride Nitrite Bromide Nitrate Phosphate Sulfate RESULTS AND DISCUSSION The ion chromatographic system was applied for the separation and determination of seven inorganic anions. Based on obtained chromatograms we can conclude that from seven tested anions only four anions (fluoride, chloride, nitrate, and sulfate) were in the detectable range of concentrations. It means that the contents of bromide, phosphate and nitrite in samples are less than DL for IC method (see Table 1). The measured and specified on labels data about the content of anions in bottled waters are shown in Table 2. The concentrations of fluoride, chloride, nitrate and sulfate were found to vary in wide ranges, namely, , , , and mg/dm 3, respectively. Table 2. Results of the complex analysis of mineral waters Water label Season of the year, 2010 Fluoride Chloride Nitrate Sulfate Aras Autumn 0.27( ) ( ) (*) (+) Winter Kulak Autumn 0.32( ) (+) ( ) (+) Winter Koohrang Autumn 0.23( ) ( ) ( ) ( ) Winter Damavand Autumn 0.2(+) 0.13 (*) (+) ( ) Winter Hayat Autumn 0.54(+) ( ) ( ) ( ) Winter Zamzam Autumn (*) (*) 3.23 (*) (*) Winter Kosalan Autumn 0.1(+) ( ) ( ) ( ) 3.94 Winter Nina Autumn (*) ( ) (+) ( ) 6.01 Winter

4 256 DARAEI et al. Table 2. Results of the complex analysis of mineral waters Table 2. (Contd.) Aouraman Autumn 0.8(+) 0.07 (*) (*) (+) 7.56 Winter Vata Autumn 0.11( ) ( ) (+) ( ) Winter Notes: (+) shows the meaningful difference between the mean value of analysis and the label value, ( ) shows the absence of these differences; and (*) shows the results that can t be tested because of the lack of label value or different label values for two samples; 1 means label, 2 means experimental. For all brands of waters, except Zamzam, label values for two samples taken in different seasons were similar. Therefore, two samples of each brand can be considered as the repeated samples and the corresponding mean value for these samples can be compared with the label values. The obtained experimental values were compared with the values on the labels and were examined by one-sample T-test using MINITAB14 software package with the value of P equal to 0.05 [17, 18]. The one-sample T-test procedure shows the difference of the mean of two experimental values from the label value. As follows from Table 2, eleven tests of the total number of T-tests (equal to 31) show a meaningful difference between the results of our analysis and the label values. The samples of output data of T-test for fluoride and nitrate of Hayat brand are presented in Table 3. Based on P values in this table, we can conclude that our data for the fluoride ion have a meaningful difference from label values, unlike the nitrate content that does not differ from label values provided the specified value of P is used. Table 3. The samples of T-test output data for fluoride and nitrate in the bottled water of Hayat brand Anion Number of tests Mean St. Dev. SE Mean 95% CI T-test P Fluoride ( 0.007, 0.247) Nitrate (3.753, ) CI means confidence interval. On the other hand, the season can be considered as an independent factor because it may affect the ion content in mineral water as it was revealed in the case of Zamzam brand labels. Hence, the dependent variable representing the ion concentration was analyzed by the two-way ANOVA using the brand and season as independent variables; this analysis was performed by using MINITAB 14 software [19]. The two-way analysis of variance allows us to test the combined equality of mean values, when the classification of variants is done by two variables or factors. The results of two-way ANOVA are presented in Table 4. As can be understood from values of P (observed significances), the differences related to the seasons are insignificant, while the differences related to brands of mineral waters are quite significant. It leads to a conclusion that no additional analyses are needed for each season of the year, and the annual analysis of each of the specified mineral bottled water is adequate. Table 4. Output data of the two-way ANOVA representing the relationship of the concentration as function of water brand and season Parameter DF SS MS F P Brand Season Error Total Notes: SS means sums of squares; MS means mean square; F (ratio) means Fisher statistic; and P means P-value. CONCLUSIONS The concentration of anions in mineral bottled water was determined by using the ion chromatography technique. All detected anions had concentrations below the MLC values established by WHO and USEPA. The anion content in at least 11 brands of bottled water is remarkably different from the values declared by producers. Although the anion contents in bottled waters were confirmed to be below the allowed levels, their

5 SIMULTANEOUS DETERMINATION 257 concentrations are not specified by producers of these waters. The two-way ANOVA revealed that different production seasons during the water sampling did not lead to meaningful differences in anion contents. ACKNOWLEDGEMENTS The financial support of the Kurdistan Environmental Health Research Center and Kurdistan University of Medical Sciences is gratefully acknowledged. REFERENCES 1. Saad, B., et al., Analysis of anions and cations in drinking water samples by capillary ion analysis, Food Chem., 1998, vol. 61, no. 1 2, pp Jackson, P.E., Determination of inorganic ions in drinking water by ion chromatography, TrAC Trends in Anal. Chem., 2001, vol. 20, no. 6 7, pp US EPA, F.R., 1998, vol. 63, no. 170, FR Environmental Protection Agency (EPA), Office of Drinking Water. Drinking Water Criteria Document on Fluoride, Washington, DC: T. U.E.P.A., Saleh, M.A., et al., Chemical evaluation of commercial bottled drinking water from Egypt, J. Food Composition and Analysis, 2001, vol. 14, no. 2, pp Lockhart, E., Tucker, C., and Merritt, M., The effect of water impurities on the flavor of brewed coffee, J. Food Sci., 1955, vol. 20, no. 6, pp Romano, J.P. and Krol, J., Capillary Ion electrophoresis, an environmental method for the determination of anions in water, J. Chromatography A, 1993, vol. 640, no. 1 2, pp Oehrle, S.A., Analysis of anions in drinking water by capillary ion electrophoresis, Ibid., 1996, vol. 733, no. 1, pp Jackson, P., Laikhtman, M., and Rohrer, J., Determination of trace level perchlorate in drinking water and ground water by ion chromatography, Ibid., 1999, vol. 850, no. 1. pp Creed, J.T. and Brockhoff, C.A., Isotope dilution analysis of bromate in drinking water matrices by ion chromatography with inductively coupled plasma mass spectrometric detection, Anal. Chem., 1999, vol. 71, no. 3, pp Hautman, D.P. and Bolyard, M., Analysis of oxyhalide disinfection by-products and other anions of interest in drinking water by ion chromatography, J. Chromatography A, 1992, vol. 602, no. 1, pp Romano, J.P. and Krol, J., Regulated methods for ion analysis, Ibid., 1992, vol. 602, no. 1 2, pp Small, H., Stevens, T., and Bauman, W., Anal. Chem., 1975, vol. 47, pp Stefanovich, C., Bolancha, Sh.,T., and Tsurkovich, L., Simultaneous determination of six inorganic anions in drinking water by non-suppressed ion chromatography, J. Chromatography A, 2001, vol. 918, no. 2, pp Buchberger, W., Detection techniques in ion chromatography of inorganic ions, TrAC Trends in Analytical Chemistry, 2001, vol. 20, no. 6, pp Miller, J.N. and Miller, J.C., Statistics and Chemometrics for Analytical Chemistry, 5th ed, 2005, Harlow, England ; New York: Pearson Prentice Hall, Zamberlan da Silva, M.E., et al., Comparison of the bacteriological quality of tap water and bottled mineral water, Int. J. Hygiene and Environ. Health, 2008, vol. 211, no. 5 6, pp Prabhakar, A., et al., The effect of water purification systems on fluoride content of drinking water, J. Ind. Soc. of Pedodontics and Preventive Dentistry, 2008, vol. 26, no. 1, pp Amitai, Y., Winston, G., Sack, J., et al., Gestational exposure to high perchlorate concentrations in drinking water and neonatal thyroxine levels, Thyroid, 2007, vol. 17, no. 9, pp Translated by A. Zheldak