Unveiling Bottled Water Perils: Investigating Phthalate Ester Acid Leaching from Bottled Water in Qatar’s Scorching Climes ^†

Abstract

Plastic bottles have gained widespread popularity due to their durability, affordability, and recyclable nature. Phthalic acid esters (PAEs) are used as plasticizers in PET bottle production, which has raised concerns regarding their presence in the environment and potential adverse effects on health, including carcinogenic and endocrine-disrupting properties. PAEs can migrate from PET bottles into the contents, especially when exposed to high temperatures. This study is the first study in Qatar to determine the leaching of DBP, BBP, and DEHP in local PET drinking water bottles under different stressful thermal conditions. GC–MS is a susceptible instrument, and it is an ideal technique to detect and quantify PAEs in collected local plastic water bottles under different storage temperatures, namely at room temperature, 24 °C; 50 °C; and cyclic temperatures of 70 °C. The limits of detection for DBP, BBP, and DEHP were 0.09, 0.33, and 0.93 µg/L, respectively. Five local brands of PET bottles in Qatar were collected and stored under thermal conditions (24, 50, and 70 °C cyclic). Three kinds of leached PAEs, including dibutyl phthalate (DBP), Benzyl butyl phthalate (BBP), and Bis(2-ethylhexyl) phthalate (DEHP), were detected by GC–MS , ranging from 2.84 to 17.32, 1.16 to 21.35, and 0.01 to 19.59 ng/L, respectively. Significant differences were observed between room temperature 24 °C, 50 °C, and cyclic temperature for concentrations of DBP, BBP, and DEHP.

1. Introduction

Water is vital for human survival, as the human body is mainly made up of water, ranging from about 50 to 60% on average for adults (both women and men). The average adult human requires 3.3–4.5 L of water daily for active physical activity [1]. The geographical location of Qatar on the northeastern coast of the Arabian Peninsula in the Middle East comprises an arid desert and a long Arab Gulf shoreline of beaches and dunes. Polyethylene terephthalate (PET) has become widely used due to its durability, affordability, and recyclability [2]. Qatar faces challenges regarding freshwater resources, rainfall, and groundwater levels [3]. Qatar has three primary desalination plants, one in Ras Abu Fontas, south of Doha, and two in Ras Laffan, to meet the country’s water supply needs [4]. Qatar experiences exceptionally high temperatures, with summer dominating most of the year. This poses a concern for water storage, as temperatures can reach 70 °C if stored in a location with metal ceilings. The extreme climate conditions in the region and prolonged storage periods can potentially exacerbate the leaching of phthalate acid esters (PAEs) from PET bottles into drinking water due to their potential carcinogens and endocrine-disrupting effects [5,6]. The permitted limit for DEHP contamination in drinking water is 6.0 µg/mL, according to the United States Environmental Protection Agency (USEPA) [7]. Consequently, local efforts focus on sustainable packaging to mitigate health and environmental concerns. This indicates that a small quantity concentrated in a water bottle could cause various health problems.

PET water bottles in the Qatar market have witnessed significant expansion over the years, driven by the country’s growing water consumption and increased demand for consumer goods due to the increasing population. This study aimed to determine the amounts of migrated DBP, BBP, and DEHP in local PET bottled mineral waters (five different brands), which were stored at stressful thermal conditions for up to 4 weeks. GC–MS-SIM was used to estimate DBP, BBP, and DEHP. To the best of our knowledge, this study is the first study in Qatar to determine the migration of DBP, BBP, and DEHP in five different local brands at 50 °C and cyclic 70 °C (for 8 h at 70 °C and for 16 h at 24 °C) from January 2024 to February 2024.

2. Experimental Section

2.1. Sample Collection

We conducted a systematic investigation of five local mineral water brands with a volume size of 200 mL (labeled subsequently with A, B, C, D, and E) classified into three different thermally stored groups of 20 at 24, 50, and cyclic 70 °C. The samples were kept at three different stressful thermal storage conditions for four weeks and sampled at weeks 1, 2, 3, and 4.

2.2. Sample Preparation

A simple liquid–liquid extraction (LLE) method of BBP, DBP, and DEHP from mineral water has been described in detail previously by the Environmental Protection Agency [8] with some modifications. Briefly, 45 mL of a seawater sample was transferred into a 50 mL conical centrifuge tube, mixed with 2 mL of dichloromethane, and spiked with 50 µL of hydrochloric acid solution (36%). The mixture was shaken manually for 1 min and then sonicated for 30 min. Afterward, the sample solution mixture was centrifuged at 200 rpm for 5 min for separation. Finally, 1 mL of the organic phase was transferred to a 2 mL clean Eppendorf tube and dried with 100 mg of sodium sulfate to eliminate the moisture before being injected into the GC–MS-SIM instrument for analysis (as seen in Figure 1).

2.3. Gas Chromatography–Mass Spectrometry (GC–MS) Analysis

Analysis DBP, BBP, and DEHP were carried out using an Agilent 6890N GC system (Agilent Technologies, Palo Alto, CA, USA) with a DB-5MS capillary column (30 m × 0.25 mm, 0.25 µm film thickness; Agilent, Santa Clara, CA, USA) equipped with an Agilent 5975B mass selective detector in electron impact mode (ionization energy set at 70 eV). The carrier gas was helium at a 1.2 mL/min flow rate. The oven temperature was initially adjusted at 60 °C for 1 min and then increased to 300 °C at 20 °C/min. Samples 3.0 µL in volume were injected using hot-splitless injection mode, with the split closed for 0.7 min. Injector and detector temperatures were set at 250 and 280 °C, respectively. The ion source temperature was set at 230 °C, and quantitative analysis was performed by SCAN mode and select ion monitoring (SIM) mode; the time for the solvent delay was set to 8.0 min.

2.4. Validation of Analytical Method According to ICH

The analytical method was validated by assessing linearity, sensitivity, specificity, and recovery according to ICH guidelines.

Linearity: A stock solution of DBP, BBP, and DEHP at 10,000 µg/L was prepared in dichloromethane. Linearity was examined by automatic injections of the standard mixture at over five different points in the investigated ranges from low to high concentrations (2.5 to 250 μg/L) in dichloromethane, and each concentration was repeated three times. The calibration curves were obtained by plotting the peak area ratio versus concentration between specific m/z ions (DBP, BBP, and DEHP).

Sensitivity: The instrumental response sensitivity is given by the slope of the calibration curve. The method with a significant slope discriminates minor differences in analyte contents. The limit of detection (LOD) and limit of quantitation (LOQ) were determined according to the following equation:

$$\mathrm{L}\mathrm{O}\mathrm{D} \mathrm{o}\mathrm{r} \mathrm{L}\mathrm{O}\mathrm{Q}=k \left({\displaystyle \frac{B}{S}}\right)$$

(1)

where k is a constant (3 for LOD and 10 for LOQ), B is the standard deviation of the analytical signal, and S is the slope.

Specificity: The specificity of the analytical method was evaluated by peak purity curves through resolution factors (R_s), the peak asymmetry factor (A_s), and the number of theoretical plates (N). The resolution factor Rs was calculated based on Equation (2):

$$R_s={\displaystyle \frac{\frac{(t_1-t_2)}{(w_2+w_1)}}{2}}$$

(2)

where t₁ and t₂ are the retention times of the two components; W₁ and W₂ are the corresponding widths at the bases of the peaks obtained by extrapolating the relatively straight sides of the peaks to the baseline.

The asymmetry factor is a measure of peak tailing and was calculated based on Equation (3):

$$A_s={\displaystyle \frac{b}{a}}$$

(3)

where A_s is the peak asymmetry factor, b is the distance from the point at the peak midpoint to the trailing edge, and a is the distance from the leading edge.

The edge of the peak to the midpoint (a and b) was measured at 10% of the peak height. The number of theoretical plates (N) was calculated using Equation (4):

$$N=16 {\left({\displaystyle \frac{t_R}{W}}\right)}^2$$

(4)

where N is the number of theoretical plates, t_R is the retention time, and W is the width at the bases of the peak.

Accuracy: The accuracy was evaluated through spiking and recovery testing. The recovery rate of PAEs at three different fortification levels (5, 20, and 50 µg/L) was evaluated to assess the extraction efficiency of the proposed method using external standards addition.

Statistics: All GC-MS-SIM analyses were performed in three replicates. The results were expressed as mean (m) ± standard deviation.

3. Results and Discussion

Analytical methods for PAEs were developed first using the SCAN mode to determine the retention time for each PAE and then using the SIM mode for quantification. SIM quantitation ions of DBP, BBP, and DEHP are shown in

Table 1. SIM quantitation ions for DBP, BBP, and DEHP.

Compound			Fragments (m/z)
	MW	Rt	1 (Quantitative)	2	3	4
DBP	278.34	10.09	149	150	76.1	223
BBP	312.36	11.93	149	91	206.1	104
DEHP	390.56	12.64	149	167	57.1	104

M_w: molecular weight (g/mol), R_t: retention time (min).

.

3.1. Validation of Analytical Method

Linearity: The linearity of the analytical method by GC-MS-SIM for PAEs (DBP, BBP, and DEHP) was assessed by preparing five different concentrations in dichloromethane at 2.50, 10, 25, 100, and 250 µg/L with three replicates (n = 3). The chromatographic responses were linear over an analytical range of 2.50–250 µg/L, entirely satisfactory, and reproducible with time. The linear regression equation was calculated using the least squares method and is summarized in

Table 2. Regression analysis of calibration curves for PAEs using the proposed method.

Compound	tR (min)	Calibration Equation	R2	RSD%	LOD	LOQ
DBP	10.1	Y = 2978.8x − 10847	0.9999	0.55	0.09	0.24
BBP	11.9	Y = 1789.6x − 55768	0.9996	0.81	0.33	0.92
DEHP	12.7	Y = 3197x − 148431	0.9994	0.60	0.93	2.65

R²: correlation coefficient, RSD: relative standard deviation.

.

The correlation coefficients were more significant than ≥0.9994, with RSD ≤ 0.94 and Rs > 2.0, indicating a robust linear relationship between the variables. The results suggested that the developed GC-MS-SIM method has a linearity.

Sensitivity: The LODs in this study for DBP, BBP, and DEHP by GC-MS-SIM were lower (0.09, 0.33, and 0.93 µg/L, respectively) compared with previous publications. Carlo et al. (2008) [9] reported that the LODs of DBP, BBP, and DEHP in wine were 150, 150, and 100 µg/L, respectively.

Recovery: The accuracy of the method was tested to verify the effectiveness of the extraction step and exclude an incorrect quantification of DBP, BBP, and DEHP. The accuracy was achieved using the technique of external standard addition at three spiked levels (5, 20, and 50 µg/L) with three replicates (n = 3). The results are summarized in

Table 3. Accuracy of the developed method.

Spiked Level (µg/L)	Average Recovery (% ± SD)
	DBP	BBP	DEHP
5	94.04 ± 3.4	98.14 ± 6.1	99.62 ± 5.7
20	91.04 ± 2.9	90.28 ± 4.8	91.22 ± 4.4
50	103.7 ± 2.9	88.95 ± $4.7$	97.82 ± 3.5

.

The recovery ranges in this study for DBP, BBP, and DEHP (91.04–103.7, 88.95–98.14, and 91.22–99.62%, respectively) are better than those reported by Carlo et al. (2008) for DBP, BBP, and DEHP at spiked levels of 100 to 500 µg/L (67–109, 71–100, and 69–90%, respectively). Thus, good recoveries with R.S.D lower than 8.2 were obtained for each PAE, confirming that the developed method was accurate.

3.2. Analysis of Real Samples

DBP, BBP, and DEHP (

Table 4. Leached concentrations of DBP (ng/L) in examined local PET bottled mineral water samples after four weeks; leached concentrations of BBP (ng/L) in examined local PET bottled mineral water samples after four weeks; leached concentrations of DEHP (ng/L) in examined local PET bottled mineral water samples after four weeks.

DBP (ng/L)

Brand

24 °C

50 °C

Cyclic Temperature (8 h at 70 °C and for 16 h at 24 °C)

1

2

3

4

1

2

3

4

1

2

3

4

A

2.90 ± 0.01

2.84 ± 0.01

2.86 ± 0.01

2.90 ± 0.01

3.37 ± 0.01

3.55 ± 0.02

3.72 ± 0.02

3.98 ± 0.02

4.69 ± 0.02

5.39 ± 0.03

5.91 ± 0.02

6.12 ± 0.03

B

n.d

n.d

n.d

n.d

n.d

n.d

n.d

n.d

n.d

n.d

n.d

n.d

C

n.d

n.d

n.d

n.d

n.d

n.d

n.d

n.d

n.d

n.d

n.d

n.d

D

n.d

n.d

n.d

n.d

n.d

n.d

n.d

n.d

n.d

n.d

n.d

n.d

E

4.77 ± 0.02

4.69 ± 0.02

4.72 ± 0.01

4.65 ± 0.02

8.58 ± 0.02

9.28 ± 0.03

11.37 ± 0.04

13.13 ± 0.03

13.23 ± 0.03

14.65 ± 0.04

15.95 ± 0.03

17.32 ± 0.04

BBP (ng/L)

Brand

24 °C

50 °C

Cyclic Temperature (8 h at 70 °C and for 16 h at 24 °C)

1

2

3

4

1

2

3

4

1

2

3

4

A

n.d

n.d

n.d

n.d

n.d

n.d

n.d

n.d

n.d

n.d

n.d

n.d

B

4.29 ± 0.02

4.35 ± 0.01

4.41 ± 0.02

4.13 ± 0.02

8.47 ± 0.04

9.23 ± 0.03

9.66 ± 0.04

10.31 ± 0.03

14.11 ± 0.02

18.11 ± 0.04

20.4 ± 0.05

21.35 ± 0.04

C

4.00 ± 0.01

4.1 ± 0.02

4.22 ± 0.03

4.32 ± 0.02

12.5 ± 0.05

15.09 ± 0.07

16.75 ± 0.06

17.92 ± 0.05

18.78 ± 0.07

19.76 ± 0.06

19.82 ± 0.08

20.45 ± 0.07

D

1.16 ± 0.02

1.22 ± 0.01

1.04 ± 0.01

1.14 ± 0.01

5.28 ± 0.02

5.64 ± 0.02

6.79 ± 0.02

7.32 ± 0.03

6.91 ± 0.03

7.61 ± 0.06

8.71 ± 0.04

9.45 ± 0.08

E

1.91 ± 0.01

1.95 ± 0.02

1.90 ± 0.01

2.12 ± 0.01

4.16 ± 0.03

6.12 ± 0.05

6.70 ± 0.07

7.24 ± 0.09

5.27 ± 0.04

6.68 ± 0.05

7.99 ± 0.08

8.24 ± 0.09

DEHP (ng/L)

Brand

24 °C

50 °C

Cyclic Temperature (8 h at 70 °C and for 16 h at 24 °C)

1

2

3

4

1

2

3

4

1

2

3

4

A

1.94 ± 0.01

2.07 ± 0.01

2.16 ± 0.02

2.14 ± 0.02

5.44 ± 0.06

6.60 ± 0.09

7.63 ± 0.11

7.85 ± 0.09

9.17 ± 0.09

12.82 ± 0.12

13.85 ± 0.09

14.59 ± 0.11

B

0.71 ± 0.01

0.78 ± 0.01

0.57 ± 0.01

0.71 ± 0.01

2.98 ± 0.02

3.63 ± 0.02

4.45 ± 0.08

5.13 ± 0.09

5.71 ± 0.12

7.42 ± 0.11

8.41 ± 0.13

9.31 ± 0.16

C

0.08 ± 0.00

0.07 ± 0.00

0.08 ± 0.00

0.08 ± 0.00

8.32 ± 0.03

9.44 ± 0.05

10.26 ± 0.12

11.26 ± 0.11

14.38 ± 0.09

16.71 ± 0.13

18.42 ± 0.12

19.59 ± 0.11

D

1.04 ± 0.01

1.17 ± 0.02

1.25 ± 0.02

1.04 ± 0.01

3.37 ± 0.04

4.06 ± 0.05

5.05 ± 0.08

6.33 ± 0.12

6.42 ± 0.08

7.05 ± 0.09

7.24 ± 0.15

7.90 ± 0.18

E

0.01 ± 0.00

0.02 ± 0.00

0.02 ± 0.00

0.07 ± 0.00

4.44 ± 0.05

5.54 ± 0.09

6.36 ± 0.11

6.76 ± 0.14

9.34 ± 0.11

10.68 ± 0.13

10.23 ± 0.12

10.90 ± 0.15

n.d: not determined.

) were detected in five local brands, which were stored under thermal conditions (24, 50, and 70 °C cyclic), and ranged from 2.84 to 17.32, 1.04 to 21.35, and 0.01 to 19.59 ng/L, respectively. Among the five local brands, the total concentrations of DBP, BBP, and DEHP for four weeks in five local brands (A, B, C, D, and E) at 24, 50, and cyclic were detected as follows: 4.84–20.71, 5.00–30.66, 4.08–30.04, 2.21–17.35, and 6.67–36.64 ng/L, respectively. Significant differences were observed between room temperature, 24 °C; 50 °C; and cyclic for concentrations of DBP, BBP, and DEHP. The leaching results in this study were better than those in published studies by Keresztes et al. (2013) [10] for DBP, BBP, and DEHP in PET mineral water in Hungary, which were 6.6–600.0, 6.0–70.0, and 16.0–1625.0 ng/L, respectively. The results of different stressful thermal conditions showed that the total concentration of PAEs in PET bottled water was safe and acceptable for human consumption.

4. Conclusions

This study’s results indicate that all five tested local water bottle brands are considered safe to consume. The contamination levels in these brands’ drinking water are below the permissible limit of 6000 ng/mL. It is important to note that these findings are based on up to four weeks of testing. Confirming these water bottle brands’ safety highlights the effectiveness of the measures taken to ensure the quality and safety of bottled water in Qatar. It emphasizes the importance of adhering strictly to regulatory standards and implementing robust quality control protocols throughout the production and packaging process. It is crucial to remain vigilant and regularly assess safety standards to address emerging issues promptly. This approach helps to mitigate potential risks and maintain the ongoing safety of bottled water.

In this study, it was noted that climatic conditions (50 °C and cyclic temperature of 70 °C), like the ones existing in Qatar during the summer season, had a direct effect on increasing the leaching concentration of DBP, BBP, and DEHP, as was shown in the study. The leachate of DBP, BBP, and DEHP that was generated during the 4-week period was for quite a small number of PAEs. While these concentration levels may not cause a risk considering the duration of this study (4 weeks), it is imperative that continuous research ensues in order to increase the duration and number of PAEs. Only a limited number of studies currently exist in GCC countries on evaluating the leaching PAEs in PET drinking bottles; these are these are issues that are really crucial and, therefore, additional research is required.