How To Study The Leaching Of Chemical Elements From Bottles

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1 Applied Geochemistry 27 (2012) Contents lists available at SciVerse ScienceDirect Applied Geochemistry journal homepage: Temperature-dependent leaching of chemical elements from mineral water bottle materials Clemens Reimann a,, Manfred Birke b, Peter Filzmoser c a Norges Geologiske Undersøkelse (NGU), Postbox 6315, Sluppen, N-7491 Trondheim, Norway b Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), Stilleweg 2, Hannover, Germany c Department of Statistics and Probability Theory, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Vienna, Austria article info abstract Article history: Received 1 March 2012 Accepted 6 May 2012 Available online 14 May 2012 Editorial handling by R. Fuge It is well established that minute amounts of chemical elements will leach from bottle materials (glass or PET polyethylene terephthalate) to water stored in such bottles. This study investigated whether leaching increases with storage temperature. For glass bottles this is clearly the case for a long list of elements: Ag, Al, As, B, Ba, Ca, Co, Cr, Cs, Cu, Fe, Ga, Ge, K, La, Li, Mg, Mo, Na, Ni, Pb, Rb, Sb, Se, Sn, Sr, Ti, U, V, W and Zr. However, for glass bottles drinking water maximum admissible concentration values as defined by European authorities are not exceeded even after 1 week of leaching at 80 C. The critical temperature limit where leaching substantially increases for many elements appears to be 45 C. For PET bottles, Sb is the only element where leaching is observed at all temperatures and again leaching strongly increases at 45 C. For PET bottles Sb concentrations observed in water after 1 week storage at 80 C reach almost four times the maximum admissible concentration values for drinking water but do not exceed the relevant higher limit for food (including water) packaged in PET. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Bottled water is increasingly replacing tap water as the main intake of drinking water in several European countries (e.g., Eisenbach, 2004; see Fig. 6 in Reimann and Birke (2010)). It is sold in cheap plastic or glass bottles and is often stored in these bottles under unpredictable conditions for several months before consumption. Misund et al. (1999) found clear indications for contamination of the water by the bottle materials, e.g., with Pb and Zr from glass bottles. More recently it has been convincingly demonstrated that glass bottles will contaminate bottled water with Pb while many polyethylene terephthalate (PET) bottles contaminate the water with Sb. Concentrations of the investigated elements increased with storage time (Shotyk et al., 2006; Shotyk and Krachler, 2007a,b; Krachler and Shotyk, 2009). Keresztes et al. (2009) report Sb concentrations of mg/kg in PET from Hungarian mineral water bottles, and significant leaching of Sb to the water depending on storage conditions and bottle volume. Welle and Franz (2011) report median concentrations of 220 mg/kg Sb in PET bottle materials and determined diffusion coefficients for Sb in PET bottles in a temperature range between 105 and 150 C. They concluded that Sb levels of water in PET bottles will not reach Corresponding author. address: clemens.reimann@ngu.no (C. Reimann). health-relevant concentrations. Reimann et al. (2010) reported results from a leaching test covering 57 chemical elements for glass and PET bottles of different color and concluded that water stored in PET bottles will be almost invariably contaminated with Sb, while glass bottles contaminate the water with a much longer list of elements (Pb, Al, Zr, Ti, Th, La, Pr, Fe, Zn, Nd, Sn, Cr, Tb, Er, Gg, Tb, Bi, Sm, Y, Lu, Yb, Tm, Nb and Cu). Concentrations of these elements in the water usually increased with storage time. In addition an influence of bottle color on the leaching results could be demonstrated. In a comment to the paper by Reimann et al. (2010), Müller-Simon (2010) pointed out that leaching of Pb from glass to water stored in glass bottles should not take place due diffusion coefficients being far too low. Based on that comment it was decided to study the leaching of chemical elements from a variety of glass bottles in three different colors in comparison to a few PET bottles at different temperatures in a range from 2 to 80 C because if diffusion is a relevant process during leaching, the concentrations of elements affected should increase with temperature. Results are used to investigate the following questions: (1) Which elements show a trend to increasing concentrations with increasing temperature of leaching and which elements remain unaffected? (2) What are the differences between different bottle colors? (3) What are the differences between the two main bottle materials glass and PET? /$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.

2 Table 1 Total element concentrations (XRF analyses) in 10 glass bottles (5 clear, 3 blue and 2 green). Some exceptionally high values are marked in bold and underscored. ID Color SiO 2 (wt.%) TiO 2 (wt.%) Al 2 O 3 (wt.%) Fe 2 O 3 (wt.%) MnO (wt.%) MgO (wt.%) CaO (wt.%) Na 2 O (wt.%) K 2 O (wt.%) P 2 O 5 (wt.%) 146-C- Blue C- Blue C- Blue C- Green ITA001-1 Green S- Clear S- Clear M- Clear HUN023-1 Clear S- Clear Ba (mg/ Bi (mg/ Ce (mg/ Co (mg/ Cr (mg/ Cu (mg/ Nb (mg/ Ni (mg/ Blue < < < Blue < Blue < < Green < < ID Color As (mg/ 146-C- 280-C- 558-C- 082-C- ITA001-1 Green < S- Clear <2 22 < < < S- Clear <2 30 < M- Clear <2 23 < <2 < HUN023- Clear <2 < <2 < S- Clear <18 < <2 < < Pb (mg/ Rb (mg/ Sb (mg/ Sc (mg/ Sn (mg/ Sr (mg/ Th (mg/ Y (mg/ Zn (mg/ Zr (mg/ C. Reimann et al. / Applied Geochemistry 27 (2012)

3 Table 2 Summary of the analytical results from the leaching test at different temperatures. Elements where no effect was observed are not shown. Values in bold indicate the onset of increased leaching. All values in lg/l. Material Color N Temp. ( C) Ag Al As B Ba Ca Co Cr Cs Cu Fe Glass Clear 9 2 Med < < < <0.002 < Max < Med < < <0.002 < Max < Med < <0.002 < Max Med < < Max Med Max Glass Blue 23 2 Med < < Max < < Med < < < Max Med Max Med Max Med Max Glass Green 5 2 Med < < Max < < Med < < Max < < Med < Max Med Max Med Max PET 3 2 Med <0.001 <0.3 < <0.1 <10 <0.002 <0.03 < <0.1 Max <0.001 <0.3 < <0.03 < Med <0.001 <0.3 < <0.1 <10 <0.002 <0.03 < <0.1 Max <0.001 <0.3 < <0.03 < Med <0.001 <0.3 < <0.1 < <0.03 < <0.1 Max <0.001 <0.3 < < <0.03 < Med <0.001 <0.3 < < <0.03 < <0.1 Max < <0.03 < Med <0.001 < <0.1 < <0.03 < <0.1 Max <0.001 < <0.03 < C. Reimann et al. / Applied Geochemistry 27 (2012) Material Color N Temp. ( C) Ga Ge K La Li Mg Mo Na Ni Pb Rb Sb Se Sn Glass Clear 9 2 Med <0.005 < < <0.001 < <0.002 < Max < < < Med <0.005 < < <0.001 < <0.002 < Max < < < Med < < < Max < < < Med < < < Max < < Med < Max Glass Blue 23 2 Med <0.005 < < <

4 Max < Med < <0.005 < < < Max <0.005 < < Med < < < Max < Med < < Max Med Max Glass Green 5 2 Med < <0.005 < < < <0.002 < Max < < < Med < <0.005 < < < Max <0.005 < < Med < < < Max < Med < < < Max < Med < < Max PET 3 2 Med < <0.005 < <0.1 <1 <0.001 < < < Max < <0.005 < <0.1 < < < Med < <0.005 <10 < <0.1 <1 <0.001 < < < Max < <0.005 < <0.1 <1 <0.001 < < < Med < <0.005 <10 < <0.1 <1 <0.001 < < < Max < <0.005 < <0.1 <1 <0.001 < < Med < <0.005 <10 < <0.1 <1 <0.001 < < < Max <0.005 < <0.1 < < < Med < <0.005 < <0.1 <1 <0.001 < < Max < <0.005 < <0.1 < < < Material Color N Temp. ( C) Sr Ti U V W Zr Glass Clear 9 2 Med < < <0.001 Max < Med <0.01 <0.002 <0.001 Max < Med <0.01 <0.002 <0.001 Max Med Max Med Max Glass Blue 23 2 Med < Max < Med <0.01 <0.002 <0.001 Max < Med <0.001 Max Med Max Med Max Glass Green 5 2 Med < Max < Med <0.01 <0.002 <0.001 Max < Med < <0.001 Max (continued on next page) C. Reimann et al. / Applied Geochemistry 27 (2012)

5 1496 C. Reimann et al. / Applied Geochemistry 27 (2012) Material and methods Table 2 (continued) Material Color N Temp. ( C) Sr Ti U V W Zr 60 Med <0.001 Max Med Max PET 3 2 Med < < <0.001 Max < < < Med <0.1 < <0.01 <0.002 <0.001 Max < <0.01 <0.002 < Med <0.1 <0.01 < <0.01 <0.002 <0.001 Max < <0.01 <0.002 < Med < <0.01 <0.002 <0.001 Max < < < Med < <0.01 <0.002 <0.001 Max < <0.01 <0.002 <0.001 Forty mineral water bottles bought in supermarkets from all over Europe were used for this test: 23 blue glass bottles, 9 clear glass bottles, 5 green glass bottles and for comparison 3 PET bottles. The volume of the bottles was 1.5 L. These bottles were thoroughly (3 times) rinsed with high purity (demineralised) water, filled with demineralised water (SERALPUR-90, 18.2 MX) and 25 ll 69% HNO 3 (Roth Suprapure, density 1.41 kg/l) was added/l to acidify the water to ph 3.5 under clean room conditions. After filling the bottles they were stored for 1 week at different temperatures (2, 22, 45, 60, 80 C) before determination of the concentrations of 60 elements (Ag, Al, As, B, Ba, Be, Bi, Br, Ca, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Fe, Ga, Gd, Ge, Hf, Hg, Ho, I, K, La, Li, Lu, Mg, Mn, Mo, Na, Nb, Nd, Ni, Pb, Pr, Rb, Sb, Sc, Se, Sm, Sn, Sr, Ta, Tb, Te, Th, Ti, Tl, Tm, U, V, W, Y, Yb, Zn and Zr) in the water using an inductively coupled plasma quadrupole mass spectrometer (ICP-QMS Agilent 7500ce). The instrument is equipped with a standard peristaltic pump, a MicroMist concentric nebulizer, a Peltier-cooled spray chamber, the Plasma Forward Power and the Shield Torch System. The methods used are in accordance with the German norms DIN E29 (ICP-MS). All details on the analytical procedure, isotopes measured, detection limits and quality control are detailed in the previous paper (Reimann et al., 2010) and in even more detail in a recent book (Reimann and Birke, 2010). To document likely average element concentrations in glass, 10 bottles (5 clear, 3 blue and 2 green) were destroyed and milled in an agate disk mill. Subsequently, 1 g of milled glass was mixed with 5 g lithium metaborate and 25 mg lithium bromide in Pt95 Au5 crucibles and fused for 20 min at 1200 C in an automatic fluxer (HAG ). Total concentrations of 10 major elements (Al 2 O 3, CaO, Fe 2 O 3,K 2 O, MgO, MnO, Na 2 O, P 2 O 5, SiO 2 and TiO 2 ) and 30 trace elements (As, Ba, Bi, Ce, Co, Cr, Cs, Cu, Ga, Hf, La, Mo, Nb, Nd, Ni, Pb, Rb, Sb, Sc, Sm, Sn, Sr, Ta, Th, U, V, W, Y, Zn, Zr) were determined by wavelength dispersive X-ray fluorescence spectrometry (WD-XRFS) using PAN2400 and AXIOS WD-XRFs with Cr- and Rh-anode X-ray tubes, respectively. To correct for matrix effects and spectral interferences calibration curves were constructed using 130 certified reference materials. In addition, special certified reference materials (SpS, Glass sand, IMRM) were analyzed together with the glass samples; all results were within 5% of the reference values. It was not possible to analyze the PET bottles because this requires a special cryogenic mill. Antimony concentrations in PET ( mg/ are, however, well established in the literature (Keresztes et al., 2009; Welle and Franz, 2011). 3. Results and discussion Table 1 shows concentrations of the 10 major oxides and 19 trace elements as found in glass bottles. For the remaining trace elements analyzed, either all or the majority of results were below the respective detection limits (Cs: 3, Ga: 2, Hf: 6, La: 15, Mo: 3, Nd: 13, Sm: 14, Ta: 4, U: 3, V: 6, W: 4 mg/. While the variation for the major oxides is small (but note Fe in green and blue bottles), trace element concentrations can vary substantially from bottle to bottle. The blue bottles show 4 5 times higher Co concentrations in the glass than all other bottles, one green bottle returned an extreme Cr concentration of 1165 mg/kg. Otherwise variation in element concentrations does not appear to depend on color, there are only single or few bottles that show extreme concentrations for certain elements, like the maximum concentration for Ba of 1925 mg/kg in a clear bottle, or for Zn of 366 mg/kg in another clear bottle. The median Pb concentration in glass is 135 mg/kg, however, 4 bottles (2 clear, 2 green) show values between 193 and 313 mg/kg. Two high values of Sb, 43 and 53 mg/kg, in a green

6 C. Reimann et al. / Applied Geochemistry 27 (2012) Fig. 1. Boxplot comparison of leaching from different bottle materials and colors at different temperatures (2, 22, 45, 60, 80 C). Storage time: 1 week at indicated temperature. All values in lg/l. and a clear bottle are also noteworthy. These large differences in the bottle composition explain the outliers observed in the leaching experiment reported in Reimann et al. (2010). Table 2 summarizes the results of 1 week leaching at different temperatures for those elements that are strongly leaching to the water and where a clear influence of temperature on bottle leach-

7 1498 C. Reimann et al. / Applied Geochemistry 27 (2012) ing was observed (Ag, Al, As, B, Ba, Ca, Co, Cr, Cs, Cu, Fe, Ga, Ge, K, La, Li, Mg, Mo, Na, Ni, Pb, Rb, Sb, Se, Sn, Sr, Ti, U, V, W and Zr). Though some leaching must again be noted for almost all elements, especially from the glass bottles, no clear effect of temperature on leaching was found for Be, Bi, Br, Cd, Ce, Dy, Er, Eu, Gd, Hf, Hg, Ho, I, Lu, Mn, Nb, Nd, Pr, Sc, Sm, Ta, Tb, Te, Th, Tl, Tm, Y, Yb and Zn. Table 2 demonstrates that for the remaining elements temperature has a clear effect on how much of an element leaches from the bottle material to the water. Note the very low concentrations reported for most elements in the PET bottles for most elements (except Sb) it is actually possible to judge the effect of leaching against the minimum concentrations observed in the PET bottles. Fig. 1 shows examples of the different behavior for temperature dependent leaching from the different bottle colors and materials. Strong leaching effects usually start at a temperature of C and in most cases leaching increases with temperature (see As and V as typical examples). Significant differences are observed for the different glass bottle colors and blue glass bottles (closely followed by the green variety) usually leach more and at lower temperatures than the clear bottles. Cobalt is an element where the effect is well visible for the blue bottles, for green glass bottles the equivalent is visible in the boxplots for Cr (Fig. 1). This is not unexpected in the light of the results presented in Table 1. Lead is one of the elements where relatively high values are observed in water stored in the glass bottles when compared to the same water stored in PET, the difference is almost 2 orders of magnitude at all temperatures. Clear glass bottles show a strong increase of Pb concentrations with temperature, while this increase is small for blue and green glass bottles, mostly because the colored glass bottles begin with quite high Pb concentrations in the water after 1 week of storage at 2 C. There can thus be little doubt that some Pb is leaching from the glass to the water and that diffusion from the glass to the water is a likely process. The diagrams also demonstrate that the leaching effect can be fairly small (1 2 orders of magnitude, e.g., V in Fig. 1) but can also cover up to 4 5 orders of magnitude for the observed element concentration (e.g., Sb in Fig. 1). Antimony is the only element that shows opposite behavior for glass and PET (Fig. 1), the water in the PET bottles shows higher Sb concentrations after only a week of storage at 2 C. There is a clear increase of Sb concentrations in the water with an increase of temperature for both bottle materials and for all colors. PET bottles show a strong increase of Sb concentrations at temperatures above 45 C (see Fig. 1). At 60 C the maximum admissible concentration for drinking water of 5 lg/l Sb (European Union, 1998) is almost reached. At 80 C a maximum value of 18 lg/l Sb is observed. The interesting situation here is that while the maximum admissible concentration for drinking water is set to 5 lg/l (European Union, 1998) this value is no longer valid once the water is packaged in PET, at that moment the packaging guideline values are valid and for Sb the value is now 40 lg/l (European Union, 2011), eight times the maximum admissible concentration for drinking water. The questions raised with regards to defining maximum admissible concentration values for drinking water in Reimann and Banks (2004) appear to be as relevant in 2012 as they were in Conclusions The results of the analysis of 10 glass bottles show large variations in the trace element content of the glass and surprisingly high maximum values (e.g., Ba, Cr, Pb, Zn). These results indicate that a larger survey into the trace element chemistry of commercial glass ware might be justified. When drinking water is stored in glass or PET bottles certain chemical elements will leach over time from the bottle material to the water. Considerably more elements leach from glass than from PET bottles. For certain elements (Ag, Al, As, B, Ba, Ca, Co, Cr, Cs, Cu, Fe, Ga, Ge, K, La, Li, Mg, Mo, Na, Ni, Pb, Rb, Sb, Se, Sn, Sr, Ti, U, V, W and Zr) leaching increases with storage temperature, while others (Be, Bi, Br, Cd, Ce, Dy, Er, Eu, Gd, Hf, Hg, Ho, I, Lu, Mn, Nb, Nd, Pr, Sc, Sm, Ta, Tb, Te, Th, Tl and Tm) appear unaffected by temperature. Although element concentrations in the water can increase by 1 2 orders of magnitude due to the contact with the bottle walls, maximum admissible concentrations for drinking water as defined by the European authorities are usually not exceeded. Leaching from PET bottles is pronounced for Sb, but this is practically the only element leaching from PET. A substantial increase of Sb concentrations occurs when the water in the bottles reaches a temperature of more than 40 C. At 80 C the maximum admissible concentration for drinking water for Sb is already exceeded by a factor of almost four. It can be concluded that storage conditions are important for bottled water quality and that storage of water in PET bottles at temperatures above 40 C should be avoided. Acknowledgements We wish to thank our colleagues Hans Lorenz of the ICP-MS lab and Frank Korte of the XRF lab at BGR for providing and analyzing the leachates and the 10 glass bottles. References DIN E29: Bestimmung von 61 Elementen durch Massenspektrometrie mit induktiv gekoppeltem Plasma (ICP-MS), Eisenbach, U., Mineralwasser. Vom Ursprung rein bis heute, Kultur- und Wirtschaftsgeschichte der deutschen Mineralbrunnen, Bonn, Verband Deutscher Mineralbrunnen e.v. (VDM). European Union, EU directive 98/83/EC of 3rd November 1998 on the quality of water intended for human consumption. Official Journal of the European, Communities, 05/12/1998, L330/ European Union, Commission Regulation (EU) No. 10/2011. On Plastic Materials and Articles Intended to Come into Contact With Food. 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