Phthalate Esters Content Research Articles

How human activities in commercial areas contribute to phthalate ester pollution in street dust of Taiwan

Exposure to phthalate esters (PAEs) poses health risks to humans. Much research has been performed evaluating PAE levels in foodstuffs, river sediment and drinking water, but little attention has been paid to their presence in urban outdoor environments where human activities are highly intense. Here we evaluated PAE presence and distribution in street dust in Kaohsiung, the most industrialized city in Taiwan. Our results showed that PAEs were ubiquitous in fifty-two street-dust samples (levels of total PAEs 5.4–989.2 mg kg−1). Di-(2-ethylhexyl) phthalate was the most abundant congener observed and made up 85.0%, 79.7%, and 97.2% of the total PAEs found in industrial, residential and commercial areas, respectively. PAE levels in street dust in commercial areas (night markets) were significantly higher, suggesting a higher risk of contamination on people present in these areas (H value > χU2). In residential and commercial areas, the higher the intensity of human activity, the higher the PAE content observed. PAE content decreased progressively from the center to the outskirts of the Houjing night market, suggesting that the increased human and consumer activities inside this commercial hotspot were the main PAE source in street dust. Children had higher estimated daily intakes (DIs) than adults and dermal absorption contributed more to these levels than oral ingestion. Although all calculated DIs were below referenced danger thresholds, street dust PAEs in the area should remain an environmental concern especially since night markets play an important role in Taiwanese/Asian culture and economy. Contrary to other studies, PAEs in this study were found less related to industrial manufacturing activities but highly linked to commercial activities. These findings are relevant for future pollution prevention efforts dedicated to mitigating public exposure to PAEs. Main findingsPAE levels in street dust are related to commercial activities. Night markets, an important commercial activity in Taiwan, were found to contribute considerably to PAE contamination in street dust.

Occurrence of phthalate esters around the major plastic industrial area in southern Taiwan

The increasing usage and disposal of plastic products could cause the wide distribution of phthalate esters (PAEs) in various environmental media. In this study, six PAE compounds, namely dimethyl phthalate, diethyl phthalate, di-n-butyl phthalate, benzyl butyl phthalate, di(2-ethylhexyl) phthalate (DEHP), di-n-octyl phthalate, were analyzed in various samples collected from the major plastic industrial area of southern Taiwan, including soil, fertilizer and plastic products, for the purposes of identifying of the possible sources of PAEs and assessing the related health risk. The results show that PAEs in soil samples was dominated by DEHP, with the total concentrations in the range of 0.7 ± 0.5, 0.2 ± 0.1, and 0.3 ± 0.2 mg kg−1 for soil samples from farmland, household back gardens and the roadside, respectively. Contents of PAEs in chemical fertilizer (ND—0 0.87 mg kg−1) were higher than that in organic fertilizer (ND—0.08 mg kg−1), and PAEs concentrations (ND—316 mg kg−1) in plastic mulching films were much less than those in the other types of plastic products (ND—1719 mg kg−1), implying that major sources of PAEs in agricultural soil could be the use of chemical fertilizer and plastic products other than plastic mulching films. Health risk assessment suggested that, via the exposure to PAEs in soil, the potential non-cancer and carcinogenic risks for adults and children are minimal in most cases, except that a “moderate” carcinogenic risk for children exposure to DEHP. The results of this study can serve as a reference for further pollution prevention and environmental protection plans in relation to the industrial operation and discharge as well as the farming practices.

Validation of a QuEChERS-Based Gas Chromatography-Mass Spectrometry (GC-MS) Method for Analysis of Phthalate Esters in Grain Sorghum.

A modified QuEChERS-based GC-MS method was developed for the determination of phthalate esters (PAEs) in grain sorghum (GS). The ubiquitous presence of PAEs can migrate into GS. Therefore, evaluation of the total content of PAEs in GS is helpful to understand its impact of overall pollution level on other foods. This study has provided some basic information in terms of the content and contamination of PAEs in GS, which is helpful to establish relevant standards and risk assessment of GS for the government.

Method development for determination of migrated phthalate acid esters from polyethylene terephthalate (PET) packaging into traditional Iranian drinking beverage (Doogh) samples: a novel approach of MSPE-GC/MS technique.

In the current study, a novel magnetic solid phase extraction (MSPE) technique combined with a gas chromatography/mass spectroscopy (GC/MS) was developed to determine the phthalate ester content of bottled Doogh samples. Doogh is a yogurt-based drinking beverage, which is frequently consumed in Middle East and Balkans. It is produced by stirring yogurt in Chern separation machine and consists of substances such as water, yogurt, and salt in addition to aqueous extracts of native herbs. The magnetic multi-walled carbon nanotubes (MWCNT-Fe3O4) were used as adsorbents of phthalate acid esters (PAEs) due to a superior adsorption capability of hydrophobic compounds. In this context, the quantity of the extractable migrated phthalate esters (dibutyl phthalate (DBP), dimethyl phthalate (DMP), butyl benzyl phthalate (BBP), diethyl phthalate (DEP), di-N-octyl phthalate (DNOP), and bis (2-ethylhexyl) phthalate (DEHP)) from polyethylene terephthalate (PET) bottles into Doogh samples was measured. The correlation between the concentration of migrated PAEs and some factors such as the type of Doogh (gaseous and without gas), difference in brand (five brands), volume (1500 and 300mL), and the storage time also was investigated. The migration level into Doogh samples was increased by incorporating of gas as well as increasing the volume of PET bottles. Also, with elaborating of storage time, the migration of some phthalates such as DEHP (the mean from 2419.85ngL-1 in the first week to 2716.15ngL-1 in the second month), DEP, and total phthalate was increased. However, no significant difference in concentrations of migrated phthalate esters among different examined brands was noted. Finally, the concentration of migrated PAEs from bottle into all the examined Doogh samples was below the defined standards by EPA; 6μg/L for DEHP in drinking water. Graphical abstract ᅟ.

Phthalate ester distributions and its potential-biodegradation microbes in the sediments of Kaohsiung Ocean Dredged Material Disposal Site, Taiwan

The aim of this study was to examine the effect of dumping harbor dredged sediments into the ocean on the phthalate esters distribution in the sediments of Kaohsiung Ocean Dredged Material Disposal Site (KODMDS). Compared with the sediments outside the disposal site (Area R), the particle size distribution of sediment in disposal site has no significant difference, because the pattern of particle size distribution in the dredged sediments is similar to that in the sediments of KODMDS. Results indicated that the mean phthalate ester content in the centres of the four disposal areas (Area I) were significantly (p < 0.05) higher than those in Area R, whereas those in the vertex angles of disposed area (Area II) were no significantly higher than those in Area R. This result implied that the dredged sediments were mainly deposited inside the disposal area, and the surface sediments in KODMDS may be impacted by the disposal of dredged sediments. The percentage of sediment samples for phthalate esters content exceeding Maximum Permissible Concentrations (MPC) and/or Ecotoxicological Serious Risk Concentrations (SRCeco) in Areas I and II was higher than that in Area R, indicated that the disposal of dredged sediments may increase the potentially ecological risks for benthic organisms that lived in the surface sediments of KODMDS. However, the present study has found the bacteria have the ability to degrade PAEs in KODMDS, indicating PAEs in KODMDS could be biodegraded eventually.

Matrix Effects in Detection of Phthalate Esters from Wheat by a Modified QuEChERS Method with GC/MS

Nowadays, there is a lack of information regarding the occurrence and the content of phthalate esters (PAEs) contamination in wheats. In this study, a QuEChERS-GC/MS method was validated to measure trace levels of 14 PAEs in wheats. The work also focused on the matrix effects (MEs) which were evaluated through the study of slope ratios obtained of solvent and wheat matrix curves. All of the PAEs had positive MEs, and the percentage values were in a range of 5.4% (diisobutyl phthalate) to 53.7% (di-n-hexyl phthalate). The average recoveries (spiked at 0.06, 0.20, and 0.60 mg kg−1) had been considered satisfactory values between 84.8 and 120.3% with relative standard deviations of 0.6–9.0% for intra-day precision and 1.0–8.6% for inter-day precision. The limits of detection and limits of quantification ranged from 0.1 to 2.5 μg kg−1 and 0.13 to 5.0 μg kg−1, respectively. Following the employment of a top-down empirical model, the relative expanded measurement uncertainties were in the range of 21–43% (coverage factor k = 2, at 95% confidence). Based on the established method, PAEs in seven commercial wheat were evaluated, where 5 out of 14 studied PAEs were revealed in all of wheats, ranging from 0.028 to 0.669 mg kg−1. One of them exceeded the upper limits 0.3 mg kg−1 set for dibutyl phthalate in China.

Determination and assessment of phthalate esters content in sediments from Kaohsiung Harbor, Taiwan

Phthalate esters (PAEs) are known organic endocrine disruptors. The distribution of 10 PAEs in sediments of Kaohsiung Harbor of Taiwan was studied using organic solvents extraction and quantified by gas chromatography/mass spectrometry. The average concentration of total PAEs (ΣPAEs) in the sediment was 8713±11,454ng/g dw with di-(2-ethylhexyl) phthalate (DEHP) (3630ng/g-dw) and diisononyl phthalate (DiNP) (3497ng/g dw) being the major species, which constitutes of 41.7% and 40.1% of ΣPAEs. PAEs concentration was relatively high near the river mouths, especially in Love River mouth, and diminished toward the harbor. Based on the sediment quality guidelines developed from previous studies, several of the observed PAE levels exceeded the Maximum Contaminant Level, especially for DEHP and thus may cause adverse effect in aquatic organisms.

Distribution of phthalate esters in agricultural soil with plastic film mulching in Shandong Peninsula, East China

The content of phthalate esters (PAEs) was investigated in 36 vegetable fields with plastic film mulching in Shandong Peninsula, East China. Soils at depths of 0–10 cm, 10–20 cm, and 20–40 cm were collected, and 16 PAEs were analyzed by gas chromatography–mass spectrometry. PAEs were detected in all the analyzed samples. The total contents of the 16 PAEs (Σ16PAEs) ranged from 1.374 to 18.810 mg/kg, with an average of 6.470 mg/kg. Among the four areas of Shandong Peninsula, including Qingdao, Weihai, Weifang, and Yantai, the highest Σ16PAE in the soil was observed in Weifang district (9.786 mg/kg), which is famous for large-scale vegetable production. Despite the significant differences among the Σ16PAEs, the PAE compositions in soils with plastic film mulching in Shandong Peninsula were comparable. Diethyl phthalate (DEP), diisobutyl phthalate, and di(4-methyl-2-pentyl) phthalate were present in all the samples, whereas di-n-hexyl phthalate was detected only in Qingdao (∼1%) and dicyclohexyl phthalate was observed only in Weifang (5.7–8.2%) in low proportions. The ratios of dimethyl phthalate, DEP, and di-n-butyl phthalate, which exceeded allowable concentrations, were 63.9–100% at different soil depths, indicating high PAE pollution. The concentration of butyl benzyl phthalate detected only in Weifang exceeded the recommended allowable soil concentration. Overall, the high PAE content in the soil with plastic film mulching in Shandong Peninsula is an issue of concern because of the large amounts of plastic film used.

Distribution and sources of oxygenated non-hydrocarbons in topsoil of Beijing, China.

The oxygenated non-hydrocarbon compounds are widely distributed in soil. To investigate the distribution and origin of these compounds in topsoil of Beijing, their contents and compositions were measured in topsoil from 62 sites in Beijing. The research results showed that oxygenated non-hydrocarbons were composed primarily of C6∼C28 n-fatty acids, C12∼C28 n-fatty alcohols, n-fatty acid methyl esters, phthalates, sterols, and dehydroabietic acid in the topsoil of Beijing. The contents and compositions of these compounds varied with the sampling site. The concentrations of n-fatty acids and phthalate esters were the highest at all sites, followed by sterols, n-fatty acid methyl esters, fatty alcohols, and dehydroabietic acid in order. The n-fatty acids had a main peak of C16, followed by C18. An odd or even carbon number predominance was not observed in the low-molecular-weight n-fatty acids, indicating a fossil fuel or organic matter source. However, some high-molecular-weight n-fatty acids with an even carbon predominance may derive from a biomass. The n-fatty alcohols showed a main peak of C22 and were predominated by an even carbon number, suggesting plant, microbial, or other natural origins. Phthalates, including diethyl phthalate (DEP), diisobutyl phthalate (DIBP), dibutyl phthalate (DBP), diethylhexyl phthalate (DEHP), and dimethylphthalate (DMP), were detected. The content of phthalate esters was higher in the samples collected from dense human activity areas. The concentrations of DBP, DEHP, and DIBP were relatively high, indicating an anthropogenic source. The sterols (predominantly β-sitosterol) originated from biological sources, especially plants. The n-fatty acid methyl esters and dehydroabietic acid in topsoil showed apparent even carbon predominance with the former mainly derived from microorganisms or plants and the latter from cork combustion products.

Monitoring of phthalates in foodstuffs using gas purge microsyringe extraction coupled with GC–MS

Phthalate esters (PAEs) are commonly used as nonreactive plasticisers in vinyl plastics to increase the flexibility of plastic polymers. Numerous studies have indicated that the PAEs as a class of endocrine-disrupting chemicals. In addition, the studies have also shown that a major source of human exposure to phthalates is the diet. To date, the largest problem in PAEs analysis is the high blank value because PAEs are widely used in various applications and products. To overcome this shortcoming, gas purge microsyringe extraction (GP-MSE) was applied, which established a new and low-blank-value analytical method for PAE analysis to analyse PAEs in foodstuffs. In this study, GP-MSE was used as a clean-up method, and the overall recoveries ranged from 85.7 to 102.6%, and the RSD was less than 10%. More importantly, this method can overcome the problem of the high blank value in PAE analysis. This method was applied for measuring PAEs in 78 foodstuffs. The results showed that a wide variety of PAE concentrations were found in the different groups, and the content of PAEs (varies from 658 to 1610ngg−1 fresh weight) is greatest in seafood. The concentrations were in the following order: DEHP>DBP>DEP≈DMP>BBP≈DNOP. Finally, the daily intake of PAEs was estimated for adults based on the levels of PAEs in foodstuffs. The total EDIdiet values of 3.2 and 12.9μgkg−1 bw d−1 were calculated for DEHP based on the mean and highest concentrations in foodstuffs, respectively.

Determination of selected phthalates by gas chromatography–mass spectrometry in mural paintings from Palermo (Italy)

Phthalate esters for decades, and probably even now, were used as softeners in water-based paintings. In general, these compounds are dangerous owing to their carcinogenicity and reproductive effects. Phthalates are not chemically but only physically bound to the matrices, hence, they may be leached into the environment and are ubiquitously found in environmental matrices. Considering that, construction is one of most important fields in Europe, and probably worldwide, with respect to its economic, technological and environmental impact.In the present work the phthalate esters content of several mural paintings was evaluated by gas chromatography–mass spectrometry (GC-MS). Because, this issue is especially important to ensure proper security measurements during processes that could involve particulate inhalation, the total concentrations of 15 compounds in the analyzed mural paintings, ranged from 0.8 to 236mg/Kg d.w. with an average of 39.4mg/Kg d.w. The highest concentration was found in a mural painting sampled in an apartment built about 50years ago, though, building age was not significantly correlated with the levels of total and single PAEs. Among the monitored phthalates, only four (bis(2-ethylhexyl) phthalate, diisobutyl phthalate, Di-n-butyl phthalate and diethyl phthalate) were detected in appreciable quantities. Benzyl butyl phthalate was relevant only for one sample and, at trace levels, only for two samples. In all tested mural paintings, except two samples, predominates the bis(2-ethylhexyl) phthalate (DEHP) (from 30 to 100% of total). In general, occasionally, dinonyl phthalate (DNP) was used as an alternative to DEHP, however, in our case, its occurrence was not found. Diisobutyl phthalate (DiBP) was detected in seven samples and ranged from 0.17 to 13.2mg/Kg d.w.

Determination of phthalate esters content in plastic articles: Comparison of extraction methods

Two variants of solvent extraction method (by Soxhlet and ultrasonic) for phthalate esters (DEHP) recoveries in PVC samples were compared. Solvent and extraction time for both techniques were also studied. DEHP content was quantified by GC-MS. The results obtained were compared using statistical methods (LSD test, t-test). 16-Hours DCM Soxhlet and 2-h DCM ultrasonic extraction methods were more convenient with respect to recovery, precision and practicability.

An easy and sensitive analytical method of determination of phthalate esters in children's toys by UPLCMS/MS

In the European Community, selected phthalate esters (PE) are restricted in their use for the manufacture of toys and childcare articles. As PE are mainly used as plasticizers for poly(vinyl chloride) (PVC), a high sensitivity analytical method was developed to determine the PE content in PVC toys by using ultra high performance liquid chromatography coupled with electronic spray mass spectrum (UPLCMS/MS). The LOD of the method is low to the level of ng/L. The method was verified by specificity, linearity, sensitivity, accuracy and precision. This research will provide a useful and convenient way to monitor the production of PVC toys.

Determination of Phthalate Esters Content in Plastic Articles: Comparison of Extraction Methods

Determination of Phthalate Esters Content in Plastic Articles: Comparison of Extraction Methods

Influence of Land Use Types on Levels and Compositions of PAEs in Soils from the Area around Hongze Lake

6 congeners of phthalate esters (PAEs) were analyzed in soils with various land use types from the area around Hongze Lake, the fourth largest freshwater lake in China. The total concentrations of 6 congeners (Σ6PAEs ) were 5.070-2.067, 0.723-2.050, 0.331-1.645, 0.002-0.173 mg kg-1 in surface soil from plastic film greenhouse (PG), conventional vegetable fields (CV), plastic film greenhouse-rice rotated fields (PR), and uncultured land (UL), respectively. DnBP and DEHP were dominant species in PAEs averagely accounted for 46.4% and 47.0% of the Σ6PAEs concentrations in all surface soils. And congener percent composition of PAEs in surface soils from uncultured land was considerably different from cultured soils. Vertical distribution of PAEs in soil profile was influenced by land use type, congener species, and the content of congener in surface soil, etc. However, the amounts of PAEs in surface soil accounted more than 58.5% of total amounts in soils. In addition, no significant relationship was observed between total organic C or pH and the concentrations of PAEs in surface soil. The contents of PAEs in soils from the area around Hongze Lake were related with land use types, especially with the use of plastic film. And the general contamination level in soil was comparable or lower than those present in other areas. According to our knowledge, this is the first study to examine the present status of PAEs in soils from the area around Hongze Lake

Levels, Distribution, and Health Risk of Phthalate Esters in Urban Soils of Beijing, China

The content of phthalate esters (PAEs) was investigated in urban soil samples ( = 127, 0-20 cm) collected from a business area (BU), classical garden (CL), culture and educational area (CU), large public green space (LA), residential area (RE), and roadside area (RO) in Beijing. The sum of all PAE contents ranged from 1.9 to 3141.7 ng/g, with an average of 1139.6 ± 727.6 ng/g. Di-n-butyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP) were the major contaminants in the soil samples. The content of DEHP and DBP in the urban soil of Beijing showed decreasing trends from the center of the city to the suburbs, which was probably because the center of the city has a longer history. In addition, higher DBP content also occurred in the south of the city, which was caused by the existence of several factories that produce commodity chemical and building materials in these areas. Because of its greater age, less disturbance from human activity, and high levels of total organic carbon and black carbon in CL, PAE content in CL was the highest among the six types of land use, followed by RE, CU, BU, LA, and RO. Although in 82.6% of the soil samples, DBP content exceeded the recommended allowable soil content in New York, USA, health risk assessment with CalTOX and Monte Carlo analysis showed that the total cancer risk values of PAEs were lower than the acceptable cancer risk value (10(-4)) and that the risk mainly came from dermal uptake and inhalation exposure pathways.

Occurrence and degradation characteristics of dibutyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP) in typical agricultural soils of China

In this study, we analyze the pollution and degradation characteristics of two kinds of phthalate esters (PEs), dibutyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP), in two kinds of soils collected from non-cultivated, crop, greenhouse, and vegetable fields from the Harbin and Handan Districts, China. The results demonstrate that DBP has relatively high residual levels in the soils, ranging from 3.18 to 29.37 mg/kg in fluvo-aquic soils of the Handan District (average 14.06 mg/kg) and 2.75–14.62 mg/kg in black soils of the Harbin District (average 7.60 mg/kg). Residual levels of DEHP reach 1.15–7.99 mg/kg in fluvo-aquic soils of the Handan District (average 4.86 mg/kg) and 0.44–4.20 mg/kg in black soils of the Harbin District (average 2.35 mg/kg). All non-cultivated soils contain the lowest contents of PEs, suggesting that the kinds of pollutants are largely derived from human agricultural activities. Laboratory experiments verify that the degradations of two kinds of PEs are mainly via microbial processes. The microbial populations are higher and reduce more slowly in black soils than those in fluvo-aquic soils. These observations might partially explain the lower levels of residuals and higher degradation rates of PEs pollutants in black soils than those in fluvo-aquic soils. The detection of DBP metabolites indicates that DBP biodegradation might begin by ester hydrolysis to form monobutyl phthalate (MBP) and corresponding alcohol. The MBP then degrades to phthalic acid or butyl benzoate, which might be possibly caused by microbial decarboxylation. The two derivatives of MBP degrade to form protocatechuate through ring cleavage.

Survey of Levels of Phthalate Ester Plasticizers in a Sewage Lagoon Effluent and a Receiving Stream

In this study, samples from a sewage treatment lagoon and those from a receiving stream were analyzed for their phthalate esters content. Knowledge of the distribution of ubiquitous phthalate esters in the sewage lagoon and the receiving stream was necessary because of the reports of their subtle toxicity to aquatic biota and humans. Liquid-liquid extraction, Clean-up experiment and High Performance Liquid Chromatography (HPLC) were the methods employed for the quantitative determination of the Phthalates. A study of uncontaminated water was done to establish blank levels. The sewage lagoon and the receiving stream were grossly polluted as several phthalate ester plasticizers: DMP, DEP, DPhP, DBP, DEHP, DOP and DINP were found present at monthly mean levels of between 24.02 mg/L and 139.25 mg/L in the sewage treatment lagoon and 10.41 mg/L and 80.53 mg/L in the receiving stream. The results showed higher levels of phthalate esters in the sewage lagoon compared to the receiving stream. The sewage lagoon was identified as a pollution point source into the receiving stream. Levels of phthalates obtained from the receiving stream are much higher than the water criteria of 3 microg/L phthalates recommended by the United States Environmental Protection Agency (USEPA) for the protection of fish and other aquatic life in water and the Suggested No-Adverse Effect Levels (SNAEL) of 7.5-38.5 microg/L for drinking water. This should give cause for great environmental concern. Peoples' health downstream is at stake and so is the 'health' of the ecosystem.

Analysis of adipate ester contents in poly(vinyl chloride) plastics by means of FT-Raman spectroscopy

Fourier transform (FT-) Raman spectroscopy excited with a 1064 nm laser can be used to determine the content of plasticizers in commercial flexible poly vinyl chloride (PVC) products. Our previous study [T. Nørbygaard, R.W. Berg, Analysis of phthalate ester content in PVC plastics by means of FT-Raman Spectroscopy, Appl. Spectrosc. 58 (4) (2004) 410–413]—on detection of the presence of phthalate esters in PVC by FT-Raman spectroscopy—is here extended to the similar case of adipate esters (AEs) in samples of soft poly vinyl chloride plastics. Spectra of a range of adipate ester plasticizers (11 AEs) in pure form are reported. We studied if qualitative and quantitative determination of the adipate ester content would be possible based on the use of proper reference samples. It was found that AEs as a group cannot be definitively identified by their characteristic Raman bands because other aliphatic dicarboxylic esters have very similar bands. This limits the detection as to what kind of ester and how much is present in a sample. An essential finding was however that one can use the absence of any Raman band in the 1020–1060 cm −1 range of the adipate esters, as a means to verify that a given soft PVC plastics sample does not contain significant amounts of phthalate esters because these plasticizers do have strong bands at around 1060 cm −1. Furthermore it must be remembered that bands may occur at around 1040 cm −1 in a PVC sample for other reasons than phthalate ester content.

Analysis of phthalate ester content in poly(vinyl chloride) plastics by means of fourier transform Raman spectroscopy.

Fourier transform (FT) Raman spectroscopy is applied to a range of phthalate ester plasticizers in pure form as well as in poly(vinyl chloride) (PVC) samples. It is found that phthalate esters as a group can be identified by a set of six characteristic Raman bands. FT-Raman spectra of 22 phthalate esters are given. It is demonstrated that the presence of phthalate esters in PVC products is readily detectable by FT-Raman spectroscopy. By use of proper reference samples quantitative determination of the phthalate ester content becomes possible as well.