3.1. Quantitative analysis
To draw the calibration curves were prepared five different concentration levels of phthalate acid esters (DEHP, DBP, DEP, DNOP, BBP and DMP) at the range of 10 to 12000 ng/L (including 10, 100, 1000 and 5000 ng/L). The correlation coefficient ranged from 0.9979 to 0.9997 and the LODs (detections limit) and LOQs (quantifications limit) for the target analytes were 13 to 30 ng/L and 39 to 90 ng/L, respectively (Table 2). The recovery values of the 6 PAEs were 94.2–104.3% with the RSDs less than 7.6%. To control the quality three levels (50, 500 and 5000 ng/L) from mix of PAEs were prepared and were analyzed duplicate in several days. The inter- and intra- day precision measured for three consecutive days in triplicate analyzes and they were lower than 7.8% and 8%, respectively (Table 3). The selectivity of method was examined by analyzing 25 non-alcoholic malt beverages.
Table 2
The linear range, LOD, LOQ and coefficient of estimation of the developed MSPE technique for measurement of phthalate acid esters
Target compound
|
Linear range (ng/L)
|
Detections limit (LOD) (ng/L)
|
quantifications limit (LOQ) (ng/L)
|
Coefficient of estimation (r2)
|
Di methyl phthalate (DMP)
|
10–12000
|
23
|
69
|
0.9979
|
Di ethyl phthalate (DEP)
|
10–12000
|
15
|
45
|
0.9984
|
Di butyl phthalate (DBP)
|
10–12000
|
13
|
39
|
0.9991
|
Butyl benzyl phthalate (BBP)
|
10–12000
|
30
|
90
|
0.9990
|
Di-n-octyl phthalate (DNOP)
|
10–12000
|
18
|
54
|
0.9988
|
Bis(2- ethyl hexyl) phthalate (DEHP)
|
10–12000
|
26
|
78
|
0.9997
|
Table 3
Estimated recoveries, precisions and accuracies for determination of the PAEs compounds at three different concentrations (n = 6) in QC samples.
Target compound
|
Sample
|
Nominal concentration (ng/L)
|
Mean of calculated concentration (ng/L)
|
RSD(%) of calculated concentration (intraday)
|
RSD(%) of calculated concentration (interday)
|
RE(%) of calculated concentration
|
Estimated recoveries (%)
|
RSD(%) of calculated recovery
|
Di methyl phthalate (DMP)
|
QCI
QCII
QCIII
|
50
500
5000
|
52
503
5050
|
6.4
7.1
7.8
|
7.3
6.6
7.9
|
4
0.6
1
|
95.3
96.0
97.3
|
7.2
6.4
7.0
|
Di ethyl phthalate (DEP)
|
QCI
QCII
QCIII
|
50
500
5000
|
47
510
5100
|
5.3
6.4
6.2
|
7.1
8.0
5.8
|
-6
2
2
|
99.7
96.3
94.2
|
6.9
7.6
5.7
|
Di butyl phthalate (DBP)
|
QCI
QCII
QCIII
|
50
500
5000
|
53
505
5045
|
6.3
6.8
7.0
|
7.2
6.7
6.9
|
6
1
0.9
|
98.4
98.4
99.8
|
7.0
5.6
6.3
|
Butyl benzyl phthalate (BBP)
|
QCI
QCII
QCIII
|
50
500
5000
|
56
512
5039
|
5.6
6.4
6.5
|
5.9
7.7
7.0
|
12
2.4
0.78
|
104.3
98.3
98.6
|
5.8
7.2
6.0
|
Di-n-octyl phthalate (DNOP)
|
QCI
QCII
QCIII
|
50
500
5000
|
56
504
5105
|
5.2
7.3
6.6
|
6.3
7.2
5.9
|
12
0.8
2.1
|
98.2
98.9
97.1
|
5.7
6.9
5.8
|
Bis(2- ethyl hexyl) phthalate (DEHP)
|
QCI
QCII
QCIII
|
50
500
5000
|
49
515
5070
|
6.9
6.0
6.8
|
7.8
6.7
7.3
|
-2
3
1.4
|
101.3
98.8
98.4
|
7.0
5.6
6.9
|
3.3. Images of SEM and analysis of EDX
The SEM image and EDX analysis of the magnetic adsorbents are presented in Figs. 1 and 2. The graphs show that the placement of magnetic particle on the surface of multi wallet carbon nanotubes is comparatively uniform and after filling with magnetic particles, the surface of the multi wallet carbon nanotubes became rougher (Fig. 1). Besides, there's no significant modification is detected in the surface of construction of the magnetic adsorbents after extraction procedure. A growth in adsorbent diameter is apparent. In addition, we concluded that the adsorbent exhibited a chain-like morphology without apparent collection. This conducts to a high ability of adsorption of the adsorbent.
The chemical compounds of the prepared adsorbent were assessed by using EDX analysis. The spectrum of EDX displayed oxygen (O), iron (Fe) and carbon (C). The atomic C, Fe, and O ratio (64.6, 22.7 and 12.7, respectively) as the principal elements in the structure of prepared adsorbent confirmed the quantitative representation of the existence of Fe3O4 nanoparticles on the MWCNT surface (Fig. 2).
3.4. XRD images
By XRD analysis, the construction of multi wallet carbon nanotubes and MWCNT-Fe3O4 composites were more confirmed. The patterns of XRD of adsorbent were exhibited in Fig. 3. The strong diffraction peaks at 2θ = 31/77° and 2θ = 45/52° were shown MWCNTs and Fe3O4, respectively. The get XRD outcomes displayed that the Fe3O4 were efficaciously coated on the surface and texture of multi wallet carbon nanotubes using a co-precipitation technique.
3.5. Evaluation of phthalate esters in non-alcoholic malt beverages bottled in PET bottle
Mean concentrations and other statistical analyses of PAEs in all samples were shown in Table 4. There was a significant difference between the groups in terms of phthalate esters (P < 0/05). According to Table 4 from the research mean of all compounds in all the samples were less than the standard defined by the EPA (6000 ng/L) and WHO-EU (8000 ng/L) in drinking water, but maximum of DEHP in samples (4 samples) was upper than the EPA and WHO-EU standards (8957.87 ng/L).
Table 4
Statistical analysis of phthalate esters in non-alcoholic malt beverages(ng/L)
Target
compound
|
mean
|
SD
|
min
|
max
|
DMP
|
18.31
|
8.75
|
8.6
|
98.1
|
DEP
|
151.33
|
31.73
|
74.83
|
268.9
|
DBP
|
496.73
|
108.99
|
300.76
|
803.21
|
BBP
|
nd
|
---
|
nd
|
nd
|
DEHP
|
5944.73
|
2518.14
|
1897.12
|
8957.87
|
DnOP
|
46.16
|
13.24
|
15.43
|
97.13
|
Total
|
6657.28
|
1600.9
|
2412.5
|
9483.93
|
The mean value and range of pH in samples was 3.3 (3.18–3.53) and sugar (per 100g) was 8.7 (4,4-11.9) and gas pressure was 1140 (830–1398) millimeters of mercury (mmHg). There was a significant difference between the groups in terms of sugar content and gas pressure (P < 0/05).
M oazzen ,M et al. (2018) showed the highest concentration of PAEs in carbonated soft drinks was DEHP, that it was upper than the standard level (STL) in the 4 samples (14,008, 9301.6, 9201 and 6766.6 ng/L) and other PAEs compounds were lower than the STL, which was somewhat similar to our study (Moazzen et al. 2018).
Xu,X et al. (2019) showed 3 PAEs compounds (DBP, DMP and DEP) were measured in ten common brands of bottled water (Made of PET) in Beijing (China), ranging from 101.97 µg/kg to 709.87 µg/kg (Xu et al. 2020).
Vincenzo Russo, M et al in 2014 with the determination of PAEs in soft drinks and alcoholic drinks (light) showed that DEHP (3.6–101 ng/mL), DBP (1.9–4.4 ng/mL), DiBP (0.2–2.5 ng/mL), DEP (0.1–1.0 ng/mL) and BBP (0.08–0.8 ng/mL), are present in all samples, while iBcEP (0.08 ng/mL) and DMP (1.9 ng/mL) are present only in 1 beer sample, that was higher than compare our study (Russo et al. 2014).
Rafiei Nazari, R et al. (2017) with determine the migration modelling of PAEs from non-alcoholic beer bottles showed that storage duration increased and temperature resulted in an increase in migration level ranging from 0.6 µg/L to 2.9 µg/L, which was lower than our study (Rafiei Nazari et al. 2018).
Carnol, L et al. ( 2017) identified 6 PAEs of Luxembourgish beer stored in various containers (aluminum, glass and can bottle) and total PAEs were found in all samples at levels of 61.56 µg / L, which was upper than the present study (Carnol et al. 2017).
Victor E. Balderas-Hernández et al. (2020) identified PAEs in tequila beverage and showed that 22% of samples (65 samples) lacked PAE. DINP (1.64–3.43 mg/kg), BBP (0.05–2.91 mg/kg) and DEP (0.13–0.27 mg/kg) were found in 5 (1.69%), 37 (12.54%) and 11 (3.73%) samples, respectively. However, these levels weren’t higher than the maximum standard level of PAEs for alcoholic beverages. DEHP (0.03–4.64 mg/kg) and DBP (0.01–2.20 mg/kg) were found in 224 (75.93%) and 96 (32.54%) samples, from them just 15 (5.08%) and 10 (3.39%) samples, respectively, exceeded the maximum standard levels for alcoholic drinks. Bis(2-ethylhexyl) phthalate was the most repetitious PAEs detected in tequila and detected concentrations of DEHP were two-times higher in ultra-aged tequilas compared to those in white tequilas (Balderas-Hernández et al. 2020).
Yang, JF et al. ( 2016) measured the PAEs in non-alcoholic drinks bottled in PET from China and showed Bis(2-ethylhexyl) phthalate contained the highest median and mean contents (0.62 ng/g and 1.60 ng/g), followed by DBP (0.27 ng/g and 1.34 ng/g). (Yang et al. 2017).
Rodríguez-Ramos, R et al (2020( by evaluating plastic migrants in non-alcoholic and alcoholic drinks showed that there are 4 PAEs in the range of 0.14–1.1 µg / L in some beers, 1 PAE in the range of 1.2–1.5 µg / L in 3 grape juices and 6 PAE in several cider samples, in the range of 0.3–2.1 µg / L, which was less than the present study (Rodríguez-Ramos et al. 2020).
Wu ,PG et al. (2014) with determination of PAEs in non-alcoholic beverages showed a wide variety of PAEs contents was detected in 48 non-alcoholic beverages. Bis(2-ethylhexyl) phthalate was the most abundant PAEs compound followed by DOP, DPP and DBP. Bis(2-ethylhexyl) phthalate was detected in fruit juice samples (0.022–0.126 mg/L), sport beverages (0.015–0.098 mg/L), coffee (0.028–0.159 mg/L) and tea (0.016–0.123 mg/L), that was higher than our study (Wu et al. 2014).
March, JG et al. (2015) showed low-alcohol beer had DEHP 0.4 ± 0.2 and DBP 2.2 ± 0.4 µg/L, that DEHP was lower than our study and DBP was higher our study (March &Cerdà 2015).
Heinemeyer,G et al. ( 2013) showed that the DEHP in Beer (alcoholic) was 0.022 and in nonalcoholic Beverages was 0.020 µg/g (Heinemeyer et al. 2013).
Wang, F et al. (2017) showed DEHP in alcoholic beverages (liquor) was ranged from 0.6182 to 1.0890 µg/mL, that was higher than our study (Wang et al. 2017).
Pang, YH et al (2019) showed DEHP in alcoholic carbonated beverage and beer was not found, that was lower than our study (Pang et al. 2020).
The data comparison of this research with other articles shows differences that can be due to reasons such as: alcoholic or non-alcoholic beverage, use of plastic or other containers, contamination of raw materials or secondary contaminants during the production process, carbonated or non-carbonated beverage and also the amount of gas in carbonated beverage (pH), duration Keep in the package as well as the amount of other ingredients in the drink.
3.6. Structural relationship of parameters
Multivariate techniques and heat-map visualization were applied to evaluate the correlation between the type and levels of PAEs with brand, color, product date, pH, sugar, volume and gas pressure. Consequently, based on heat-map and PCA results, the Bis(2- ethyl hexyl) phthalate (DEHP) and total PAEs were the closest accessions, indicating that this variables had similar trends. Heat-map clustered the 40 non-alcoholic malt beverages using correlation distance and average linkage, reflecting similarities and relationship among the type and levels of PAEs samples. The heat-map clearly grouped samples into two major clusters and two sub clusters (Fig. 4). First cluster includes DEHP and total PAEs, Second cluster contains two sub-groups with brand, color, product date, pH, sugar, volume, gas pressure, DMP, DEP, DBP, BBP and DNOP.
Quantitative results obtained for the type and levels of PAEs were used to PCA to investigate the most significant contribution among non-alcoholic malt beverages. The compounds included samples brand, color, product date, pH, sugar, volume, gas pressure and levels of PAEs (DEHP, DMP, DNOP, BBP, DBP and DEP).
The dependence relations between different PAEs can be found from Fig. 4, the graph subset illustrates a visual representation about the relations among different PAEs. The nearest neighbor among the properties, the greater significant relationship existed among dependent variable.
As shown in Fig. 5, the first five principal components accounted for 77.86% of the data variance in all samples, and their contribution rates were 26.80%, 15.87%, 14.27%, 11.46% and 9.43%, respectively. The DEHP and total PAEs were the closest accessions, indicating which these variables had similar trends. The Total phthalate, DEP, DBP, BEHP had a high positive correlation with PC1, while had negative correlation with sugar content and gas pressure. The results showed that the sugar, pH, brand had a positive correlation with PC2, while had negative correlation with gas pressure and DOP.