Next Article in Journal
Thioredoxin 1 and Thioredoxin Reductase 1 Redox System Is Dysregulated in Neutrophils of Subjects with Autism: In Vitro Effects of Environmental Toxicant, Methylmercury
Previous Article in Journal
Evaluating Silymarin Extract as a Potent Antioxidant Supplement in Diazinon-Exposed Rainbow Trout: Oxidative Stress and Biochemical Parameter Analysis
Previous Article in Special Issue
Simultaneous Quantification of 16 Bisphenol Analogues in Food Matrices
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Toxics
Volume 11
Issue 9
10.3390/toxics11090738
toxics-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Developing an Improved Strategy for the Analysis of Polychlorinated Dibenzo-p-Dioxins/Furans and Dioxin-like Polychlorinated Biphenyls in Contaminated Soils Using a Combination of a One-Step Cleanup Method and Gas Chromatography with Triple Quadrupole Mass Spectrometry

by
Haena Chu
1,†,
Jungmin Jo
2,†,
Younggyu Son
3,4,
Ji Yi Lee
2 and
Yun Gyong Ahn
1,*
1
Western Seoul Center, Korea Basic Science Institute, Seoul 03759, Republic of Korea
2
Department of Environmental Science and Engineering, Ewha Womans University, Seoul 03760, Republic of Korea
3
Department of Environmental Engineering, Kumoh National Institute of Technology, Gumi 39177, Republic of Korea
4
Department of Energy Engineering Convergence, Kumoh National Institute of Technology, Gumi 39177, Republic of Korea
*
Author to whom correspondence should be addressed.
†
These authors contributed equally to this work.
Toxics 2023, 11(9), 738; https://doi.org/10.3390/toxics11090738
Submission received: 19 July 2023 / Revised: 16 August 2023 / Accepted: 24 August 2023 / Published: 28 August 2023
(This article belongs to the Special Issue New Advances in Analytical Method of Emerging Contaminants and Risk Assessment)
Browse Figures
Versions Notes

Abstract

:
Soils contaminated with polychlorodibenzo-p-dioxins (PCDDs), polychlorodibenzofurans (PCDFs), and dioxin-like (dl) polychlorinated biphenyls (PCBs), known as persistent organic pollutants (POPs), have garnered global attention because of their toxicity and persistence in the environment. The standard method for target analytes has been used; however, it is an obstacle in large-scale sample analysis due to the comprehensive sample preparation and high-cost instrumental analysis. Thus, analytical development of inexpensive methods with lower barriers to determine PCDDs/Fs and dl-PCBs in soil is needed. In this study, a one-step cleanup method was developed and validated by combining a multilayer silica gel column and Florisil micro-column followed by gas chromatography with triple quadrupole mass spectrometry (GC-QqQ-MS/MS). To optimize the separation and quantification of 17 PCDDs/Fs and 12 dl-PCBs in soils, the sample cleanup and instrumental conditions were investigated. For quantification method validation, spiking experiments were conducted to determine the linearity of the calibration, recovery, and method detection limit of PCDDs/Fs and dl-PCBs using isotopic dilution GC-QqQ-MS/MS. The applicability of the simultaneous determination of PCDDs/Fs and dl-PCBs was confirmed by the recovery of native target congeners and labeled surrogate congeners spiked into the quality-control and actual soil samples. The results were in good agreement with the requirements imposed by standard methods. The findings in this work demonstrated the high accessibility of the sample cleanup and analysis methods for the efficient determination of PCDDs/Fs and dl-PCBs in contaminated soils.

1. Introduction

Polychlorodibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are a group of chemical compounds that are persistent organic pollutants (POPs). Moreover, a group of polychlorinated biphenyls (PCBs), referred to as dioxin-like (dl) PCBs or coplanar PCBs, are treated as less potent versions of PCDDs/Fs due to their similar molecular structures and properties. Coplanar PCBs, including four non-ortho-substituted (PCB 77, 81, 126, and 169) and eight mono-ortho-substituted (PCB 105, 114, 118, 123, 156, 157, 167, and 189) congeners, are particularly toxic [1]. From the perspective of human exposure, 17 PCDDs/Fs and 12 dl-PCBs are considered as toxicologically concerning materials by the World Health Organization (WHO) (Table S1).
PCDDs/Fs and dl-PCBs are mainly produced through various sources, such as industrial processes, incomplete combustion of fuels, and waste incineration [2,3,4]. These compounds are considerably stable during environmental and biological degradation, resulting in their persistence in the environment and bioaccumulation in the food chain. Moreover, they cause various biological toxicities in humans, plants, and soil [5,6,7]. The most toxic congener, 2,3,7,8-tetrachlorodibenzo-para-dioxin (TCDD), exhibits severe toxicological effects, such as damage to the immune system, teratogenesis, and tumor promotion [8,9,10].
In 2004, the Stockholm Convention on POPs emphasized the control and reduction of environmental exposure to POPs, of which PCDDs/Fs and dl-PCBs are considered as representative substances. Furthermore, numerous countries have started regulating them at both the screening and action levels, as well as prohibiting their industrial discharge under Clean Water Act Effluent Guidelines [11,12]. Therefore, new analytical methods are being developed to monitor the toxicity of PCDDs/Fs and dl-PCBs in different matrices, such as water, food, soil, and air, for large-scale sample analysis.
Most studies have focused on the direct exposure of the human body to POPs through food, animal feeds, and air; however, few studies have considered the contamination and toxicity of POPs in soil. The POP concentration in soil varies depending on the type of soil; the PCDD/F and dl-PCB concentrations in soil around industrial parks and incinerators are higher than in other environmental matrices [13,14,15,16].
In Korea, the maximum residue level (MRL) for PCDDs/Fs in soil has recently been established and emission standards for dl-PCBs are being prepared [17]. The sample preparation and analytical methods for the contaminant groups, PCDDs/Fs and dl-PCBs, have already been published by authorized organizations, such as the United States Environmental Protection Agency (USEPA) [18,19,20,21]. However, these methods have limitations with respect to monitoring numerous samples from the perspective of sample cleanup and instrumental analysis. From the perspective of sample cleanup, the open-column cleanup procedure is labor-intensive and time-consuming. Moreover, this procedure requires a large space for sample preparation as well as large amounts of hazardous solvents. An automated PCDDs/Fs cleanup system overcomes the drawbacks of the manual method in terms of time and labor. However, the costs of installation (approximately $100,000) and maintenance are high. The aforementioned factors have spurred the development of more simplified, small-scale, and time-saving methods with reasonable cost, such as contaminated soil remediation technology [22,23,24,25]. For instance, the micro-column sample cleanup procedure takes a shorter time, and simplifies and reduces laboratory work when compared with the traditional manual methods, such as the USEPA method 1613 [26,27,28]. The methods proposed in this study are semiautomatic methods that can overcome the disadvantages of both traditional and automatic preparation methods. Moreover, the developed methods require a minimum workspace and reasonable cost. A gas chromatograph–high-resolution mass spectrometer (GC-HR/MS), which is mainly used for quantifying PCDDs/Fs and dl-PCBs, has excellent advantages and high sensitivity; however, methods based on GC-HR/MS incur high initial-investment and maintenance costs and require skilled operators. Furthermore, GC-HR/MS exhibits easy contamination after a high-concentration analysis, thereby requiring extreme care during the analytical procedure. Therefore, sample inspections are expensive, i.e., approximately $2000 per sample in South Korea and $500–$2500 per sample in other countries, depending on the urgency [29]. Thus, efforts are being made toward the development of alternative analytical methods.
In a previous study, gas chromatography with triple quadrupole mass spectrometry (GC-QqQ-MS/MS) has been successfully used as an alternative and cost-effective analytical method for determining 17 PCDDs/Fs in contaminated soil [30]. This study aims to develop an analytical procedure combining a fast, miniaturized sample cleanup method and cost-effective GC-QqQ-MS/MS analysis for quantification of 17 PCDDs/Fs and 12 dl-PCBs in contaminated soil. To our knowledge, no attempt has been made to combine a fast, miniaturized sample cleanup with a GC-QqQ-MS/MS analysis technique. A simultaneous, simple, and eco-friendly cleanup method was employed using one-step cleanup columns for effectively separating POP congeners. For the GC-QqQ-MS/MS analysis, the analytical conditions were optimized for separating and quantifying PCDDs/Fs and dl-PCBs. For validating the quantitative method, spiking experiments were conducted to determine the linearity, recovery, and method detection limit (MDL) of PCDDs/Fs and dl-PCBs. The developed method could be applied for the inspection of 17 PCDDs/Fs and 12 dl-PCBs in contaminated soil, and is also expected to be used in various detection methods, such as MRL monitoring.

2. Materials and Methods

2.1. Chemical and Reagents

Standard solutions of PCDDs/Fs and PCBs congeners, namely, EPA-1613 STOCK (Native Stock Solution), EPA-1613 LCS (13C12-labeled compound stock solution), EPA-1613 ISS (internal standard solution), and EPA-1613 CVS (calibration and verification solutions, CS1–CS4) for PCDDs/Fs, and WP-STOCK, WP-LCS, WP-ISS, and WP-CVS (CS1–CS6) for dl-PCBs, were purchased from Wellington Laboratories Inc. (Guelph, ON, Canada). The organic solvents n-hexane and DCM and ethyl ether for pesticide residue analysis (all of analytical grade) were purchased from J.T. Baker (Phillipsburg, NJ, USA). Anhydrous sodium sulfate (Na2SO4) from FUJI-FILM Wako Chemicals USA Corporation (Richmond, VA, USA) and 95% sulfuric acid from Merck (Darmstadt, Germany) were used. The multilayer silica gel column packed in a glass tube (O.D. 6.35 mm × length 35 cm) was purchased from Supelco (Bellefonte, PA, USA). This column was composed of 3 g 10% Ag-NO3/silica gel, 0.9 g silica gel, 22% H2SO4/silica gel, 4.5 g 44% H2SO4/silica gel, 0.9 g silica gel, 3 g 2% KOH/silica gel, and 0.9 g silica gel. Florisil with a mesh size of 60–100 mesh purchased from Merck was used.

2.2. Extraction of PCDDs/Fs and dl-PCBs from Soil Samples

To perform the quality assurance and quality control (QA/QC), a pooling sample of diatomaceous earth purchased from Duksan Science (Seoul, Republic of Korea) was used as the blank and control samples without target analytes. For the actual sample analysis, the samples excavated from areas near industrial complexes with suspected soil contamination were used. The details of the soil sampling have been described in a previous study [30].
For method validation, 0.025–250 ng of native standards of PCDDs/Fs and dl-PCBs were spiked into accurately weighed soil (20 g). Subsequently, 1 ng of EPA-1613 LCS and 0.5 ng of WP-LCS were added to the soil samples, and 20 g of anhydrous Na2SO4 was homogenously mixed to avoid moisture. The soil samples were then sonicated for 30 min with 100 mL of acetone:n-hexane (1:1, v/v) in an ultrasonic bath (frequency = 531 kHz). The organic solvent layer was filtered through 5 g of anhydrous Na2SO4 using qualitative filter paper (Advantec®, Tokyo, Japan). The extract (300 mL) was collected by repeating the sonication and filtration processes thrice. The spiked extract was evaporated (Eyela, Tokyo, Japan) to remove acetone, dissolved in 100 mL n-hexane, and transferred into a separate funnel. The extracts were cleaned via sulfuric acid treatment before multilayer column chromatography to avoid clogging the column with sample residues because soil matrices usually have high contents of natural organic compounds, such as humic substances, lipids, pigments, and fulvic acids [31]. The extracted n-hexane layer was repeatedly treated with concentrated sulfuric acid until a colorless sample was obtained. The sample was then washed with 100 mL of deionized distilled water. The solvent of the extract was evaporated and concentrated under N2 flow and dissolved with 50 μL of nonane. Ultrasonic extraction, filtration, and concentration were similarly applied to the extraction of the actual sample performed during the validation test.

2.3. Sample Cleanup

To separate PCDDs/Fs and dl-PCBs from the samples, a Florisil column was used. Supelco Dioxin Prep System–Florisil Version is a manual system that consists of a multilayer silica column coupled in series with a Florisil micro-column. Florisil was preactivated overnight at 130 °C. The micro-column was filled with 0.2 g of Na2SO4 (upper layer) and 1 g of preactivated Florisil (lower layer); considerable skill is required for conducting this step. Before cleanup, the multilayer silica column was conditioned with 150 mL of n-hexane and the Florisil micro-column was conditioned by adding 10 mL of DCM, followed by 100 mL of n-hexane.
The multilayer silica gel column was then coupled over the Florisil micro-column. The concentrated extract was loaded to the top surface of the silica gel column. The first 25 mL of eluate (F1) was discarded. Consequently, 175 mL of n-hexane (F2–F8) and 25 mL of 2% DCM/n-hexane (2:98, v/v, F9) were collected from the connected columns for the dl-PCB fraction. For the PCDD/F fraction, 75 mL of DCM (F10–F12) was sequentially collected. Each fraction was concentrated via N2 gas purging and spiked with 1 ng of EPA-1613 ISS and 0.5 ng of WP-ISS. The final volume of the sample was adjusted to 50 μL using nonane and used for analysis.

2.4. Instrumental Analysis

GC–QqQ-MS/MS was performed using a system with a 7890B gas chromatograph coupled with a 7010 triple quadrupole mass spectrometer (Agilent Technologies, USA). The analytes were separated using a DB-5MS UI capillary column (5% diphenyl, 95% dimethyl siloxane phase, and 60 m × 0.25 mm × 0.25 μm) from J&W Scientific (Folsom, CA, USA). A 2 μL sample was injected in the splitless mode at 280 °C and 310 °C for dl-PCBs and PCDDs/Fs, respectively. A liner with a capacity of 990 μL, an inner diameter of 4 mm, and a length of 78 mm was used. For the dl-PCB analysis, the GC oven was programmed to an initial temperature of 150 °C and held at this temperature for 1 min. Thereafter, the oven was sequentially heated up to 200 °C, 260 °C, and 300 °C at 20, 2, and 10 °C/min, respectively, and held at these temperatures for 1, 4, and 10 min, respectively. For the PCDD/F analysis, the GC oven was programmed to an initial temperature of 160 °C and held at this temperature for 1 min. Subsequently, the oven was sequentially heated up to 200 °C, 220 °C, 235 °C, and 310 °C at 5, 5, 5, and 5 °C/min, respectively, and held at these temperatures for 2, 15, 5, and 20 min, respectively. High-purity helium (99.999%) was used as the carrier gas at a flow rate of 1 mL/min. The aforementioned measurements were conducted in the electron impact ionization (EI) mode. The electron emission energy was set to 70 eV, and the temperature of the ion source was 230 °C. The analytical conditions and each specification of the instruments are summarized in Table S2.
Each analyte was detected by selecting two specific ions (M and M+2 or M+2 and M+4) and was qualitatively analyzed by comparing the ion abundance ratio and retention time of the selected ions [32]. The quantification of the analytes was conducted using an isotopic dilution method under the dynamic MRM (dMRM) mode; this method is a good alternative for the simultaneous analysis of multicomponent samples and exhibits higher sensitivity and specificity than those of MRM [33,34]. The MRM transitions for the quantifier and qualifier utilized the two most predominant fragments for each analyte. Four individual collision energies (5, 15, 30, and 50 eV) were tested for each MRM transition. The optimized conditions for the dMRM for dl-PCBs and PCDDs/Fs are listed in Table 1.

2.5. Quality Assurance and Quality Control (QA/QC)

QA/QC procedures were performed to evaluate whether the developed analytical method meets the requirements of EPA 1613B and EPA 1668C methods in this study [35]. Linearity, MDL, limit of quantitation (LOQ) and recovery experiments of the calibration curve were performed to evaluate the QA/QC of the assay method. Peaks detected at a signal-to-noise ratio greater than 3 were used for the analysis. The average relative response factor (RRF) for the individual isomers was calculated at each concentration and averaged. The RSD of the average RRF value was <15%, which satisfies the EPA criterion. The linearity of the calibration curve was evaluated based on the determination coefficient (R2).
To assess the instrument performance and calibration during the continuous analysis, a recovery (%) test was performed by analyzing the native and 13C-labeled congeners with the mid-standard solution of the calibration curve for every 10 sample batches. The results showed that the recovery of the native and 13C-labeled PCDDs/Fs and dl-PCBs congeners satisfies the criteria of the EPA 1613B [18] and EPA 1668C [19] methods (Figure S1). Thus, GC-QqQ-MS/MS remained stable during the aforementioned analysis.

3. Results and Discussion

3.1. Optimization of the Cleanup Procedure

In the USEPA method, two columns (multilayer silica gel column and alumina column) are separately prepared in parallel, and the eluate obtained from the first column (silica gel) is concentrated. Subsequently, the eluate is newly loaded in the second column (alumina) for separation and elution. The adopted cleanup method is a one-step method that connects two columns (multilayer silica gel and Florisil column, Figure S2). Moreover, it can separate and elute PCDDs/Fs and dl-PCBs simultaneously with one loading. In this study, operational conditions such as the amount and speed of elution and the ratio of the solvent were optimized for this purpose.
Soil contamination by PCDDs/Fs and dl-PCBs are attributed to accidental spillage during the manufacture, transport, storage, and use of various chlorinated compounds in the industry as well as their disposal in unregulated landfills [36]. The concentrations of other interferences are considerably higher than those of the target analytes in contaminated soil; therefore, sample cleanup is required to remove the interferences prior to analysis and quantification. Among the sample cleanup methods, open-column absorption chromatography is commonly used for sorbents, such as silica, alumina, and Florisil [13,37,38]. In this study, a combination of multilayer silica gel and Florisil micro-columns was employed after sulfuric acid treatment. The multilayer silica gel column is used to remove interferences, including acidic and basic compounds as well as hydrolyzed fats. Furthermore, the Florisil column, which is effective in terms of recovery and resolution of dl-PCBs [39], is used for separating PCDDs/Fs and dl-PCBs with different retentions [40]. The conditions of the combined cleanup columns, namely, the specific elution solvent and flow rate, should be adjusted to the enable separation of two contaminant groups (PCDDs/Fs and dl-PCBs) in one step.
The elution properties of dl-PCBs and PCDDs/Fs with respect to the multilayer silica gel column were investigated to determine the amounts of n-hexane required to elute all congeners from the silica gel column and transfer them to the coupled Florisil micro-column (Figure S3). Because higher-chlorinated biphenyl (CB) has lower polarity, hepta-CB was eluted first with n-hexane, a non-polar solvent, and tetra-CBs were eluted last from the silica gel column. For the same reason, OCDD and OCDF were eluted first and TCDD and TCDF were eluted last with n-hexane [41,42]. It was found that 25 mL of n-hexane was to be discarded and 175 mL of n-hexane was required to elute all of the congeners of dl-PCBs and PCDDs/Fs from the silica gel column.
When congeners are fractionated using the combined columns, the elution profile (Figure 1a) shows that the non-ortho-substituted PCBs (PCB 77, 81, 126, and 169) tend to have structurally higher retention in Florisil than the mono-ortho-substituted PCBs (PCB 105, 114, 118, 123, 156, 157, 167, and 189) because of their planar conformation [43]. Penta-, hexa-, and hepta-CBs were eluted from F2 to F4 with n-hexane, and tetra-CBs are eluted from F5 to the next elution with 25 mL of 2% dichloromethane (DCM) in n-hexane (F9). The elution of most hexa- and penta-CBs was not observed in more than 100 mL of n-hexane (Figure S4). To elute the remaining congeners, DCM/n-hexane (2:98 and 5:95, v/v) and ethyl ether/n-hexane (6:94, v/v) were considered, based on previous studies [44,45,46], as shown in Table S3. There is no considerable difference in the recovery of dl-PCBs according to the solvent composition in the Florisil micro-column; however, the highest recoveries of 92.1%–102.9% for all congeners were noted when DCM/n-hexane (2:98, v/v) was used. Figure 1b shows the elution profile of PCDDs/Fs for the Florisil micro-column with DCM after eluting dl-PCBs. As shown in Figure 1b, 75 mL of DCM (F10–F12) was required to elute all the congeners of PCDDs/Fs.
The elution rate of DCM/n-hexane (2:98, v/v) in the Florisil micro-column is a key factor for separately collecting dl-PCB and PCDDs/Fs fractions. Table 2 shows the recoveries of dl-PCBs and PCDDs/Fs when DCM/n-hexane (2:98, v/v) was eluted at a rate of 1, 5, and 10 mL/min in the Florisil micro-column. The recoveries of the dl-PCBs congeners are similar at the three different elution rates, except for PCB 169 (75.1% at a rate of 10 mL/min). Non-ortho-substituted PCBs (PCB 77, 81, 126, and 169) were coeluted with the PCDDs/Fs congeners at elution rates of 5 and 10 mL/min. The recoveries of the PCDDs/Fs congeners noticeably decreased with increasing elution rate from 1 and 5 mL/min to 10 mL/min. Therefore, 1 mL/min DCM/n-hexane (2:98, v/v) and DCM in the Florisil micro-column were considered the most appropriate conditions for the complete separation of the fractions of dl-PCBs and PCDDs/Fs. The specific details of each step are presented in Figure S2.

3.2. Method Validation

The entire analytical procedure from the sample preparation to the final analysis was validated in accordance with the linearity of calibration, MDL, LOQ, and recovery. Calibration curves of the 17 PCDDs/Fs and 12 dl-PCBs were plotted using the isotope dilution method with 13C-labeled standards. The determination coefficient (R2) exhibits good linearity of more than 0.9999 over the 0.05–200 pg/µL range for 12 dl-PCBs. For the PCDDs/Fs, the R2 values were in the range of 0.9992–1 for different congener concentrations, as shown in Table 3. The MDL was measured by analyzing seven replicate samples spiked with 12.5 pg of dl-PCBs and 10–50 pg of PCDDs/Fs per 20 g control sample, which is considered free of the target analytes. MDL is defined as the lowest concentration of the dl-PCBs and PCDDs/Fs congeners, resulting in a confidence of >99% when the entire analytical procedure was conducted [47]. LOQ is defined as 10 times the standard deviation (SD) obtained using MDL. Although not the same conditions, MDL obtained through comparable previous studies were summarized and compared (Table S4). Since different approaches were used to obtain MDLs by these previous studies, comparisons with this study along the same lines are limited. Among them, MDLs for PCDDs/Fs in fly ash measured by Fan et al. (2017) using the same approach were similar to those measured in this study [48]. Even though the sample matrix and the methods of extraction and cleanup are different, it is noteworthy that the analytical instrument used by Fan et al. (2017) was an expensive and highly specialized HRGC-HRMS, rather than GC-QqQ-MS/MS used in this study. Therefore, it was found that the developed analytical method is an effective alternative method in terms of cost effectiveness for the analysis of dl-PCBs and PCDDs/Fs.
The accuracy and precision values were assessed by recovery experiments using triplicate QC samples spiked with low, medium, and high concentrations of native 17 PCDDs/Fs and 12 dl-PCBs in this study. The analytical results of the samples used for recovery that were spiked with designated concentrations are shown in Table 3. The overall recoveries ranged from 87.1%~109.0% for 17 PCDDs/Fs, and 83.5%~106.5% for 12 dl-PCBs. The precisions of dl-PCBs and PCDDs/Fs were determined as the relative standard deviation (%RSD), which was calculated from the average and the standard deviation of the replicate analysis. Both the accuracy and RSD imposed by the QA/QC guidelines were satisfied.
As shown in Figure 2, the precision and accuracy of the targeted individual PCDDs/Fs and dl-PCBs in this study are in good agreement with the QC acceptance limits imposed by the USEPA method [49].

3.3. Application to Actual Soil Samples

The developed analytical method combined with the one-step cleanup for the separation and quantification of 17 PCDDs/Fs and 12 dl-PCBs based on GC-QqQ-MS/MS was applied to the actual soil samples. Figure 3 shows a typical overlaid MRM chromatogram to compare the signals of dl-PCBs and PCDDs/Fs detected in the soil samples excavated near industrial complexes (red color) with the blank (black color) and the signal at the lowest quantifiable concentration (MDL, green color). Although dl-PCBs (1.59 pg/g for PCB 118 and 0.50 pg/g for PCB 114) are detected at extremely low concentrations, both native and label congeners are not affected by the baseline separation and interfering substances. Moreover, for PCDDs/Fs, 2.88 pg/g 2,3,4,6,7,8-HxCDF and 0.65 pg/g 1,2,3,7,8,9-HxCDF are successfully separated from any interferences at the baseline level of the actual sample.
Figure 4 shows the average recoveries of the spiked 13C-labeled surrogates of dl-PCBs and PCDDs/Fs before the sample preparation for sample analysis. The average recoveries of the labeled standards are in the range of 54.2%–90.0% with an RSD of 15% for 12 13C-dl-PCBs and 46.1%–69.9% with an RSD of 20% for 15 13C-PCDDs/Fs. These results satisfy the QC criteria of the EN 16190:2018 method (50%–130% for tetrachlorinated to hexachlorinated congeners and 40%–130% for heptachlorinated and octachlorinated congeners) [50,51,52]. The sample cleanup and instrumental analysis were confirmed to be performed under the appropriate cleanup efficiency and quantitative conditions.
To determine the residue levels of PCDDs/Fs in the environmental media for regulation purposes, the total toxic equivalent (TEQ) value based on the WHO toxicity equivalence factor (TEF) rather than the concentration of a single congener is commonly used. The total TEQ concentration value is the sum of the values obtained by multiplying the concentration of each congener by its assigned WHO-TEF. The analytical results of the representative sample with the most diverse dl-PCBs and PCDDs/Fs congeners are determined among the samples, as presented in Table S5.
More than 90% of human exposure to PCDDs/Fs and dl-PCBs originates from food, which has the lowest governmental regulatory concentration restriction among different media [53,54]. In the case of soil, the regulation level differs depending on the country or land use. In Korea, an acceptable standard of 100 pg TEQ/g has been set for PCDDs/Fs. Considering various references, the analytical method developed in this study is sufficiently applicable because the exposure limits of PCDDs/Fs and dl-PCBs in soil are in the ranges of 2.48–39,300 [55,56,57,58] and 0.05–8.8 pg TEQ/g [36,59,60], respectively.
QC samples prepared by spiking dl-PCBs and PCDDs/Fs in the middle calibration range were analyzed during sample analysis. The QC charts used to validate the analytical results obtained for every batch during sample analysis are shown in Figure 5.
Based on their degree of chlorination, 12 dl-PCBs and 17 PCDDs/Fs were categorized into homologue groups. The recoveries for each homologue group were calculated from the total concentrations of their corresponding congeners. The QC charts were constructed from the measured mean recoveries and SD of each homologue group of dl-PCBs and PCDDs/Fs for seven QC samples during sample analysis. The confidence intervals of 95% and 99% were established based on the SD values of mean ± 2SD and ±3SD, respectively [61]. Although several homologues of the PCDDs/Fs were outside the 99% confidence interval, all results were within the 95% confidence interval.

4. Conclusions

A simple and cost-effective GC-QqQ-MS/MS combined with a one-step cleanup method was optimized and evaluated for the simultaneous determination of 17 PCDDs/Fs and 12 dl-PCBs in contaminated soils. For the cleanup and separation of PCDDs/Fs and dl-PCBs, the elution conditions, such as solvent composition and elution flow rate, of the multilayer silica gel column connected with a Florisil micro-column were optimized. For optimizing the quantitative analysis with GC-QqQ-MS/MS, the dMRM mode was used to obtain improved separation and sensitivity than MRM. To evaluate the entire analytical procedure, the linearity of the calibration curve, MDL, and recovery for the target dl-PCBs and PCDDs/Fs were validated. Results proved the validity of the proposed method, which satisfies the requirements of standard official methods. The proposed method is expected to increase the accessibility of PCDDs/Fs and dl-PCBs analyses at the laboratory scale, thereby promoting the active monitoring for their regulation and broadening the scope of related research.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/toxics11090738/s1, Table S1. Physicochemical properties and toxic equivalent factors of target dl-PCBs and PCDDs/Fs; Table S2. Instrumental conditions for the quantification of dl-PCBs and PCDDs/Fs; Table S3. Recoveries (%) of dl-PCB congeners according to different elution solvent compositions; Table S4. Comparison of MDLs obtained by different extraction, cleanup, and detection methods in the previous studies with the ones in this study; Table S5. Total WHO-TEQ concentrations of dl-PCBs and PCDDs/Fs for the representative soil samples excavated near industrial complexes; Figure S1. Verification charts of (a) dl-PCBs and (b) PCDDs/Fs obtained during sample analysis to monitor the instrumental performance (GC-QqQ-MS/MS); Figure S2. Schematic of the one-step cleanup procedure; Figure S3. Elution profiles of (a) dl-PCBs and (b) PCDDs/Fs on the multilayer silica gel column; Figure S4. Chromatograms of congeners of dl-PCBs and PCDDs/Fs obtained during fractionation. References [62,63,64,65,66,67,68] are cited in the Supplementary Materials.

Author Contributions

Conceptualization, J.J., Y.S. and Y.G.A.; methodology, Y.S. and Y.G.A.; validation, H.C., J.J. and Y.G.A.; formal analysis, H.C. and J.J.; investigation, H.C. and J.J.; resources, Y.S.; data curation, H.C. and J.J.; writing—original draft preparation, H.C., J.J. and Y.G.A.; writing—review and editing, Y.S., J.Y.L. and Y.G.A.; visualization, J.J.; supervision, Y.S., J.Y.L. and Y.G.A.; project administration, Y.S. and Y.G.A.; funding acquisition, Y.S. All authors have read and agreed to the published version of the manuscript.

Funding

This work was supported by the Korea Ministry of Environment (MOE) as “Subsurface Environment Management (SEM)” Program [project No. 2021002470001] and the Korea Basic Science Institute (KBSI) research grant (C380200). This work was also supported by the Center for Women in Science, Engineering and Technology (WISET) Grant, funded by the Ministry of Science and ICT (MSIT) under the Program for Returners into R&D.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The data presented in this study are available on request from the corresponding author.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Alcock, R.E.; Behnisch, P.A.; Jones, K.C.; Hagenmaier, H. Dioxin-like PCBs in the environment-human exposure and the significance of sources. Chemosphere 1998, 37, 1457–1472. [Google Scholar] [CrossRef] [PubMed]
  2. Marinković, N.; Pašalić, D.; Ferenčak, G.; Gršković, B.; Stavljenić Rukavina, A. Dioxins and human toxicity. Arh. Hig. Rada Toksikol. 2010, 61, 445–453. [Google Scholar] [CrossRef] [PubMed]
  3. Peng, Y.; Lu, S.; Li, X.; Yan, J.; Cen, K. Formation, measurement, and control of dioxins from the incineration of municipal solid wastes: Recent advances and perspectives. Energy Fuels 2020, 34, 13247–13267. [Google Scholar] [CrossRef]
  4. Shibamoto, T.; Yasuhara, A.; Katami, T. Dioxin formation from waste incineration. In Reviews of Environmental Contamination and Toxicology: Continuation of Residue Reviews; Springer: New York, NY, USA, 2007; pp. 1–41. [Google Scholar]
  5. Lee, S.; Lim, Y.; Kang, Y.; Jung, K.; Jee, S. The association between blood concentrations of PCDD/DFs, DL-PCBs and the risk of type 2 diabetes mellitus and thyroid cancer in South Korea. Int. J. Environ. Res. Public Health 2022, 19, 8745–8754. [Google Scholar] [CrossRef] [PubMed]
  6. Tavakoly Sany, S.B.; Hashim, R.; Salleh, A.; Rezayi, M.; Karlen, D.J.; Razavizadeh, B.B.M.; Abouzari-Lotf, E. Dioxin risk assessment: Mechanisms of action and possible toxicity in human health. Environ. Sci. Pollut. Res. Int. 2015, 22, 19434–19450. [Google Scholar] [CrossRef] [PubMed]
  7. Van den Berg, M.; Birnbaum, L.S.; Denison, M.; De Vito, M.; Farland, W.; Feeley, M.; Fiedler, H.; Hakansson, H.; Hanberg, A.; Haws, L.; et al. The 2005 World Health Organization reevaluation of human and mammalian toxic equivalency factors for dioxins and dioxin-like compounds. Toxicol. Sci. 2006, 93, 223–241. [Google Scholar] [CrossRef]
  8. Marshall, N.B.; Kerkvliet, N.I. Dioxin and immune regulation: Emerging role of aryl hydrocarbon receptor in the generation of regulatory T cells. Ann. N. Y. Acad. Sci. 2010, 1183, 25–37. [Google Scholar] [CrossRef]
  9. Kossack, M.E.; Manz, K.E.; Martin, N.R.; Pennell, K.D.; Plavicki, J. Environmentally relevant uptake, elimination, and metabolic changes following early embryonic exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin in zebrafish. Chemosphere 2023, 310, 136723. [Google Scholar] [CrossRef]
  10. Tuomisto, J. WikiJournal Preprints/dioxins and dioxin-like compounds. WikiJ. Med. 2019, 6, 8. [Google Scholar] [CrossRef]
  11. Agency for Toxic Substances and Disease Registry (U.S.A). Polychlorinated Biphenyls (PCBs) Toxicity—What Standards and Regulations Exist for PCB Exposure? Available online: https://www.atsdr.cdc.gov/csem/polychlorinated-biphenyls/standards.html (accessed on 27 April 2023).
  12. United Nations Treaty Collection (UNTC). 15. Stockholm Convention on Persistent Organic Pollutants. Available online: https://treaties.un.org/Pages/ViewDetails.aspx?src=IND&mtdsg_no=XXVII-15&chapter=27&clang=_en (accessed on 10 May 2023).
  13. Li, T.; Hu, J.; Xu, C.; Jin, J. PCBs, PCNs, and PCDD/Fs in soil around an industrial park in Northwest China: Levels, source apportionment, and human health risk. Int. J. Environ. Res. Public Health 2023, 20, 3478. [Google Scholar] [CrossRef]
  14. Kim, K.S.; Shin, S.K.; Kim, K.S.; Song, B.J.; Kim, J.G. National monitoring of PCDD/DFs in environmental media around incinerators in Korea. Environ. Int. 2008, 34, 202–209. [Google Scholar] [CrossRef]
  15. Schuhmacher, M.; Nadal, M.; Domingo, J.L. Levels of PCDD/Fs, PCBs, and PCNs in soils and vegetation in an area with chemical and petrochemical industries. Environ. Sci. Technol. 2004, 38, 1960–1969. [Google Scholar] [CrossRef]
  16. Chakraborty, P.; Selvaraj, S.; Nakamura, M.; Prithiviraj, B.; Cincinelli, A.; Bang, J.J. PCBs and PCDD/Fs in soil from informal e-waste recycling sites and open dumpsites in India: Levels, congener profiles and health risk assessment. Sci. Total Environ. 2018, 621, 930–938. [Google Scholar] [CrossRef]
  17. Korea Legislation Research Institute (KLRI). Persistent Organic Pollutants Control Act (Act No. 15841). Available online: https://elaw.klri.re.kr/eng_service/lawView.do?hseq=50758&lang=ENG (accessed on 27 April 2023).
  18. Method 1613B; Tetra-through Octa-Chlorinated Dioxins and Furans by Isotope Dilution HRGC/HRMS. USEPA: Washington, DC, USA, 1994.
  19. Method 1668C; Chlorinated Biphenyl Congeners in Water, Soil Sediment Biosolids Tissue HRGC. USEPA: Washington, DC, USA, 2010.
  20. Method 8280B; Polychlorinated Dibenzo-p-Dioxins and Polychlorinated Dibenzofurans by High-Resolution Gas Chromatography/Low-Resolution Mass Spectrometry. USEPA: Washington, DC, USA, 2007.
  21. Method 8082A; Polychlorinated Biphenyls (PCBs) by Gas Chromatography. USEPA: Washington, DC, USA, 2000.
  22. Saito, K.; Takekuma, M.; Ogawa, M.; Kobayashi, S.; Sugawara, Y.; Ishizuka, M.; Nakazawa, H.; Matsuki, Y. Extraction and cleanup methods of dioxins in house dust from two cities in Japan using accelerated solvent extraction and a disposable multi-layer silica-gel cartridge. Chemosphere 2003, 53, 137–142. [Google Scholar] [CrossRef] [PubMed]
  23. Do, L.; Xuan, T.H.; Lundstedt, S.; Haglund, P. Modular pressurized liquid extraction for simultaneous extraction, clean-up and fractionation of PCDD/Fs in soil, sediment and sludge samples. Anal. Methods 2013, 5, 1231–1237. [Google Scholar] [CrossRef]
  24. Kedikoglou, K.; Costopoulou, D.; Vassiliadou, I.; Bakeas, E.; Leondiadis, L. An effective and low cost carbon based clean-up method for PCDD/Fs and PCBs analysis in food. Chemosphere 2018, 206, 531–538. [Google Scholar] [CrossRef] [PubMed]
  25. Naert, C.; Van Peteghem, C. Development and application of a simplified clean-up procedure for the determination of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in horse fat by gas chromatography-tandem mass spectrometry (GC-MS/MS). Food Addit. Contam. 2007, 24, 1018–1025. [Google Scholar] [CrossRef]
  26. Fernandes, A.; White, S.; D’Silva, K.; Rose, M. Simultaneous determination of PCDDs, PCDFs, PCBs and PBDEs in food. Talanta 2004, 63, 1147–1155. [Google Scholar] [CrossRef]
  27. Beníšek, M.; Kukučka, P.; Mariani, G.; Suurkuusk, G.; Gawlik, B.M.; Locoro, G.; Giesy, J.P.; Bláha, L. Dioxins and dioxin-like compounds in composts and digestates from European countries as determined by the in vitro bioassay and chemical analysis. Chemosphere 2015, 122, 168–175. [Google Scholar] [CrossRef]
  28. Degrendele, C.; Fiedler, H.; Kočan, A.; Kukučka, P.; Přibylová, P.; Prokeš, R.; Klánová, J.; Lammel, G. Multiyear levels of PCDD/Fs, dl-PCBs and PAHs in background air in central Europe and implications for deposition. Chemosphere 2020, 240, 124852. [Google Scholar] [CrossRef]
  29. Reiner, E.J. The analysis of dioxins and related compounds. Mass Spectrom. Rev. 2010, 29, 526–559. [Google Scholar] [CrossRef] [PubMed]
  30. Jo, J.; Son, Y.; Lee, J.; Lee, D.; Shin, J.H.; Ahn, Y.G. Gas chromatography-triple quadrupole mass spectrometry as a cost-effective method for the determination of polychlorinated dibenzo–p-dioxins and furans in contaminated soils. Chemosphere 2022, 308, 136286. [Google Scholar] [CrossRef] [PubMed]
  31. González-Curbelo, M.Á.; Varela-Martínez, D.A.; Riaño-Herrera, D.A. Pesticide-residue analysis in soils by the QuEChERS method: A review. Molecules 2022, 27, 4323. [Google Scholar] [CrossRef]
  32. Franchina, F.A.; Lazzari, E.; Scholl, G.; Focant, J.F. Assessment of a new GC-MS/MS system for the confirmatory measurement of PCDD/Fs and (N) dl-PCBs in food under EU regulation. Foods 2019, 8, 302. [Google Scholar] [CrossRef]
  33. Stone, P.; Glauner, T.; Kuhlmann, F.; Schlabach, T.; Miller, K. New Dynamic MRM Mode Improves Data Quality and Triple Quad Quantification in Complex Analyses; Agilent Publication: Santa Clara, CA, USA, 2009. [Google Scholar]
  34. Liang, J.; Wu, W.Y.; Sun, G.X.; Wang, D.D.; Hou, J.J.; Yang, W.Z.; Jiang, B.H.; Liu, X.; Guo, D.A. A dynamic multiple reaction monitoring method for the multiple components quantification of complex traditional Chinese medicine preparations: Niuhuang Shangqing pill as an example. J. Chromatogr. A 2013, 1294, 58–69. [Google Scholar] [CrossRef]
  35. Rao, Q.; Wang, X.; Zhang, Q.; Hoogenboom, R.; Li, H.; Deng, Z.; Song, W.; Cheng, L.; Liu, X.; Guan, S.; et al. New insights into the transfer and accumulation of dioxins and dioxin-like PCBs in the food web of farmed Chinese mitten crabs: A typical case from the Yangtze River area. J. Hazard. Mater. 2022, 436, 129178. [Google Scholar] [CrossRef]
  36. Dömötörová, M.; Sejáková, Z.S.; Kočan, A.; Čonka, K.; Chovancová, J.; Fabišiková, A. PCDDs, PCDFs, Dioxin-like PCBs and indicator PCBs in soil from five selected areas in Slovakia. Chemosphere 2012, 89, 480–485. [Google Scholar] [CrossRef]
  37. Gao, Y.; Zhang, H.; Chen, J.; Zhang, Q.; Tian, Y.; Qi, P.; Yu, Z. Optimized cleanup method for the determination of short chain polychlorinated n-alkanes in sediments by high resolution gas chromatography/electron capture negative ion–low resolution mass spectrometry. Anal. Chim. Acta 2011, 703, 187–193. [Google Scholar] [CrossRef]
  38. Amakura, Y.; Tsutsumi, T.; Sasaki, K.; Toyoda, M.; Maitani, T. Comparison of sulfuric acid treatment and multi-layer silica gel column chromatography in cleanup methods for determination of PCDDs, PCDFs and dioxin-like PCBs in foods. Shokuhin Eiseigaku Zasshi 2002, 43, 312–321. [Google Scholar] [CrossRef]
  39. Ren, M.; Peng, P.-A.; Zhang, S.-K.; Deng, Y.-Y.; Mai, B.-X.; Sheng, G.-Y.; Fu, J.-M. Determination of 2,3,7,8-Substitituted polychlorinated dibenzo-p-dioxins-dibenzofurans and dioxin-like polychlorinated biphenyls in environmental samples by gas chromatography/high resolution mass spectrometry. Chin. J. Anal. Chem. 2007, 35, 176–180. [Google Scholar] [CrossRef]
  40. Erdmann, S.E.; Dietz, R.; Sonne, C.; Bechshøft, T.Ø.; Vorkamp, K.; Letcher, R.J.; Long, M.; Bonefeld-Jørgensen, E.C. Xenoestrogenic and dioxin-like activity in blood of East Greenland polar bears (Ursus maritimus). Chemosphere 2013, 92, 583–591. [Google Scholar] [CrossRef]
  41. Li, F.; Jin, J.; Tan, D.; Xu, J.; Dhanjai, Y.; Ni, Y.; Zhang, H.; Chen, J. High performance solid-phase extraction cleanup method coupled with gas chromatography-triple quadrupole mass spectrometry for analysis of polychlorinated naphthalenes and dioxin-like polychlorinated biphenyls in complex samples. J. Chromatogr. A 2016, 1448, 1–8. [Google Scholar] [CrossRef]
  42. Huckins, J.N.; Schwartz, T.R.; Petty, J.D.; Smith, L.M. Determination, fate, and potential significance of PCBs in fish and sediment samples with emphasis on selected AHH-inducing congeners. Chemosphere 1988, 17, 1995–2016. [Google Scholar] [CrossRef]
  43. Wells, D.E.; Hess, P. Separation, clean-up and recoveries of persistent trace organic contaminants from soils, sediment and biological matrices. Tech. Instrum. Anal. Chem. 2000, 21, 73–113. [Google Scholar]
  44. Zhao, X.; Cui, T.; Guo, R.; Liu, Y.; Wang, X.; An, Y.X.; Qiao, X.; Zheng, B. A clean-up method for determination of multi-classes of persistent organic pollutants in sediment and biota samples with an aliquot sample. Anal. Chim. Acta 2019, 1047, 71–80. [Google Scholar] [CrossRef] [PubMed]
  45. Aries, E.; Anderson, D.R.; Ordsmith, N.; Hall, K.; Fisher, R. Development and validation of a method for analysis of “dioxin-like” PCBs in environmental samples from the steel industry. Chemosphere 2004, 54, 23–31. [Google Scholar] [CrossRef]
  46. Reick, R. Separation of toxic coplanar PCB congeners from other congeners in marine sediments and marine fish tissues using Florisil and GC-ECD. LC-GC N. Am. 2003, 21, 992–1000. [Google Scholar]
  47. USEPA. Definition and Procedure for the Determination of the Method Detection Limit, Revision 2; USEPA: Washington, DC, USA, 2016.
  48. Fan, Y.; Zhang, H.; Wang, D.; Ren, M.; Zhang, X.; Wang, L.; Chen, J. Simultaneous determination of chlorinated aromatic hydrocarbons in fly ashes discharged from industrial thermal processes. Anal. Methods 2017, 9, 5198–5203. [Google Scholar] [CrossRef]
  49. Method 23; Determination of Polychlorinated Dibenzo-p-Dioxins and Polychlorinated Dibenzofurans from Stationary Sources. USEPA: Washington, DC, USA, 2023. Available online: https://www.epa.gov/system/files/documents/2023-03/2023 (accessed on 30 June 2023).
  50. EN 16190:2018; Soil, Treated Biowaste and Sludge—Determination of Dioxins and Furans and Dioxin-like Polychlorinated Biphenyls by Gas Chromatography with High Resolution Mass Selective Detection. CEN: Brussels, Belgium, 2018; European standards.
  51. Kalbe, U.; Lehnik-Habrink, P.; Bandow, N.; Sauer, A. Validation of European horizontal methods for the analysis of PAH, PCB and dioxins in sludge, treated biowaste and soil. Environ. Sci. Eur. 2019, 31, 29. [Google Scholar] [CrossRef]
  52. Cerasa, M.; Guerriero, E.; Mosca, S. Evaluation of extraction procedure of PCDD/Fs, PCBs and chlorobenzenes from activated carbon fibers (ACFs). Molecules 2021, 26, 6407. [Google Scholar] [CrossRef]
  53. Całkosiński, I.; Rosińczuk-Tonderys, J.; Bazan, J.; Dobrzyński, M.; Bronowicka-Szydełko, A.; Dzierzba, K. Influence of dioxin intoxication on the human system and possibilities of limiting its negative effects on the environment and living organisms. Ann. Agric. Environ. Med. 2014, 21, 518–524. [Google Scholar] [CrossRef]
  54. Wang, Y.L.; Fei, S.Y.; Wang, T.W.; Liu, X.T.; Gao, X.N.; Wu, H.T.; Hu, K. PCDD/Fs and DL-PCBs in Chinese mitten crab (Eriocheir sinensis) and its farming environment in Shanghai, China. Foods 2022, 11, 2556. [Google Scholar] [CrossRef] [PubMed]
  55. Leung, A.O.; Luksemburg, W.J.; Wong, A.S.; Wong, M.H. Spatial distribution of polybrominated diphenyl ethers and polychlorinated dibenzo-p-dioxins and dibenzofurans in soil and combusted residue at Guiyu, an electronic waste recycling site in southeast China. Environ. Sci. Technol. 2007, 41, 2730–2737. [Google Scholar] [CrossRef]
  56. Le, L.T.H.; Dat, N.D.; Minh, N.H.; Nguyen, K.A. Characteristics of PCDD/Fs in soil and sediment samples collected from A-So former airbase in Central Vietnam. Sci. Total Environ. 2019, 661, 27–34. [Google Scholar] [CrossRef] [PubMed]
  57. Pan, J.; Yang, Y.; Zhu, X.; Yeung, L.W.Y.; Taniyasu, S.; Miyake, Y.; Falandysz, J.; Yamashita, N. Altitudinal distributions of PCDD/Fs, dioxin-like PCBs and PCNs in soil and yak samples from Wolong high mountain area, eastern Tibet-Qinghai Plateau, China. Sci. Total Environ. 2013, 444, 102–109. [Google Scholar] [CrossRef]
  58. Nhung, N.T.H.; Nguyen, X.T.; Long, V.D.; Wei, Y.; Fujita, T. A review of soil contaminated with dioxins and biodegradation technologies: Current status and future prospects. Toxics 2022, 10, 278. [Google Scholar] [CrossRef]
  59. Al-Wabel, M.I.; Usman, A.R.A.; El-Saeid, M.H.; Al-Turki, A.M.; Hassanin, A.S.; El-Mubarak, A.H. Levels, sources, and risk assessment of polychlorinated biphenyls (PCBs) in soils from industrial areas: A case study from Saudi Arabia. Polycycl. Aromat. Compd. 2018, 38, 420–433. [Google Scholar] [CrossRef]
  60. Wu, J.; Hu, J.; Wang, S.; Jin, J.; Wang, R.; Wang, Y.; Jin, J. Levels, sources, and potential human health risks of PCNs, PCDD/Fs, and PCBs in an industrial area of Shandong Province, China. Chemosphere 2018, 199, 382–389. [Google Scholar] [CrossRef] [PubMed]
  61. Focant, J.F.; De Pauw, E. Fast automated extraction and clean-up of biological fluids for polychlorinated dibenzo-p-dioxins, dibenzofurans and coplanar polychlorinated biphenyls analysis. J. Chromatogr. B Analyt. Technol. Biomed. Life Sci. 2002, 776, 199–212. [Google Scholar] [CrossRef]
  62. Shiu, W.Y.; Doucette, W.; Gobas, F.A.; Andren, A.; Mackay, D. Physical-chemical properties of chlorinated dibenzo-p-dioxins. Environ. Sci. Technol. 1988, 22, 651–658. [Google Scholar] [CrossRef]
  63. Dossier, E. Polychlorinated Dibenzo-p-Dioxins (PCDDs), Polychlorinated Dibenzofurans (PCDFs), and Dioxin-Like Polychlorinated Biphenyls (dl-PCBs). Prepared by the Sub-Group on Review of the Priority Substances List (under Working Group E of the Common Implementation Strategy for the Water Framework Directive. 2011, p. 35. Available online: https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwiD2_WYpP-AAxUSh_0HHRGMBfsQFnoECBEQAQ&url=https%3A%2F%2Fcircabc.europa.eu%2Fd%2Fa%2Fworkspace%2FSpacesStore%2Ff0d90906-c361-4af1-82b1-d2e52f826c14%2FDioxins%252520%252526%252520PCBDL%252520EQS%252520dossier%2525202011.pdf&usg=AOvVaw1AS25hsN8bD82UnwB7IZly&opi=89978449 (accessed on 18 July 2023).
  64. Sun, H.; Wang, P.; Li, H.; Li, Y.; Zheng, S.; Matsiko, J.; Hao, Y.; Zhang, W.; Wang, D.; Zhang, Q. Determination of PCDD/Fs and dioxin-like PCBs in food and feed using gas chromatography-triple quadrupole mass spectrometry. Sci. China Chem. 2017, 60, 670–677. [Google Scholar] [CrossRef]
  65. Zhang, H.; Zhao, X.; Ni, Y.; Lu, X.; Chen, J.; Su, F.; Zhao, L.; Zhang, N.; Zhang, X. PCDD/Fs and PCBs in sediments of the Liaohe River, China: Levels, distribution, and possible sources. Chemosphere 2010, 79, 754–762. [Google Scholar] [CrossRef] [PubMed]
  66. Nghiem, T.X.; Hoang, A.Q.; Nguyen, T.D.; Nguyen, T.T.; Tran, P.D.; Nguyen, T.T.; Tu, M.B. PCDD/Fs and Dioxin-like PCBs in Chicken Eggs and Soils in Dong Nai Province, Southern Vietnam: Impacts of Raising Methods and Nearby Pollution Sources. Bull. Environ. Contam. Toxicol. 2022, 108, 136–144. [Google Scholar] [CrossRef] [PubMed]
  67. Cloutier, P.-L.; Fortin, F.; Groleau, P.E.; Brousseau, P.; Fournier, M.; Desrosiers, M. QuEChERS extraction for multi-residue analysis of PCBs, PAHs, PBDEs and PCDD/Fs in biological samples. Talanta 2017, 165, 332–338. [Google Scholar] [CrossRef]
  68. Aguilar, L.; Williams, E.S.; Brooks, B.W.; Usenko, S. Development and application of a novel method for high-throughput determination of PCDD/Fs and PCBs in sediments. Environ. Toxicol. Chem. 2014, 33, 1529–1536. [Google Scholar] [CrossRef]
Toxics 11 00738 g001
Figure 1. Elution profiles of (a) dl-PCBs and (b) PCDDs/Fs using the combined columns (multilayer silica gel and Florisil micro-column). The shaded part of the graph represents the elution volumes for dl-PCB fraction eluted by 175 mL of n-hexane and 25 mL of 2% dichloromethane (DCM) in n-hexane and PCDD/F fraction eluted by 75 mL of DCM.
Figure 1. Elution profiles of (a) dl-PCBs and (b) PCDDs/Fs using the combined columns (multilayer silica gel and Florisil micro-column). The shaded part of the graph represents the elution volumes for dl-PCB fraction eluted by 175 mL of n-hexane and 25 mL of 2% dichloromethane (DCM) in n-hexane and PCDD/F fraction eluted by 75 mL of DCM.
Toxics 11 00738 g001
Toxics 11 00738 g002
Figure 2. Precision and accuracy of native (a) dl-PCBs and (b) PCDDs/Fs under the optimum conditions of sample preparation obtained by the recovery assays. The bars represent the mean recoveries of the native congeners spiked into the control samples (n = 9). The error bars indicate the relative standard deviation (RSD). The red dots represent the upper and lower QC limits imposed by EPA 1668C and EPA 1613B methods.
Figure 2. Precision and accuracy of native (a) dl-PCBs and (b) PCDDs/Fs under the optimum conditions of sample preparation obtained by the recovery assays. The bars represent the mean recoveries of the native congeners spiked into the control samples (n = 9). The error bars indicate the relative standard deviation (RSD). The red dots represent the upper and lower QC limits imposed by EPA 1668C and EPA 1613B methods.
Toxics 11 00738 g002
Toxics 11 00738 g003
Figure 3. Overlay signals of the MRM chromatograms obtained by a blank, experimental MDL, and positive soil sample; (A) dl-PCB Chromatogram (a) 1.59 pg/g 2,3′,4,4′,5-pentachlorobiphenyl (PCB 118) and its 13C labeled standard, and (b) 0.50 pg/g 2,3,4,4′,5-pentachlorobiphenyl (PCB 114) and its 13C labeled standard, (B) PCDD/F Chromatogram (a) 2.88 pg/g 2,3,4,6,7,8-hexachlorodibenzofuran (HxCDF) and its 13C labeled standard, and (b) 0.65 pg/g 1,2,3,7,8,9-HxCDF and its 13C labeled standard.
Figure 3. Overlay signals of the MRM chromatograms obtained by a blank, experimental MDL, and positive soil sample; (A) dl-PCB Chromatogram (a) 1.59 pg/g 2,3′,4,4′,5-pentachlorobiphenyl (PCB 118) and its 13C labeled standard, and (b) 0.50 pg/g 2,3,4,4′,5-pentachlorobiphenyl (PCB 114) and its 13C labeled standard, (B) PCDD/F Chromatogram (a) 2.88 pg/g 2,3,4,6,7,8-hexachlorodibenzofuran (HxCDF) and its 13C labeled standard, and (b) 0.65 pg/g 1,2,3,7,8,9-HxCDF and its 13C labeled standard.
Toxics 11 00738 g003
Toxics 11 00738 g004
Figure 4. Average recoveries of 13C labeled (a) dl-PCBs and (b) PCDDs/Fs congeners.
Figure 4. Average recoveries of 13C labeled (a) dl-PCBs and (b) PCDDs/Fs congeners.
Toxics 11 00738 g004
Toxics 11 00738 g005
Figure 5. QC results obtained during sample analysis for each homologue group (tetra-, penta-, hexa-, hepta-, and octa-) of (a) dl-PCBs and (b) PCDDs/Fs. The total recoveries of each homologue group for dl-PCBs and PCDDs/Fs were calculated using the sum of individual congeners of the same degree of chlorination. The dotted lines represent 95% and 99% confidence intervals (±2SD and ±3SD, respectively).
Figure 5. QC results obtained during sample analysis for each homologue group (tetra-, penta-, hexa-, hepta-, and octa-) of (a) dl-PCBs and (b) PCDDs/Fs. The total recoveries of each homologue group for dl-PCBs and PCDDs/Fs were calculated using the sum of individual congeners of the same degree of chlorination. The dotted lines represent 95% and 99% confidence intervals (±2SD and ±3SD, respectively).
Toxics 11 00738 g005
Table 1. Dynamic multiple-reaction monitoring (dMRM) conditions of (a) dioxin-like (dl) polychlorinated biphenyls (PCBs) and (b) polychlorodibenzo-p-dioxin (PCDD) and polychlorinated dibenzofuran (PCDF) congeners using gas chromatography with triple quadrupole mass spectrometry (GC-QqQ-MS/MS).
Table 1. Dynamic multiple-reaction monitoring (dMRM) conditions of (a) dioxin-like (dl) polychlorinated biphenyls (PCBs) and (b) polychlorodibenzo-p-dioxin (PCDD) and polychlorinated dibenzofuran (PCDF) congeners using gas chromatography with triple quadrupole mass spectrometry (GC-QqQ-MS/MS).
CongenerQualifierQuantifierCongener
(Labeled)		QualifierQuantifier
Transitions
(m/z)		Collision Energy (eV)Transitions
(m/z)		Collision Energy (eV)Transitions
(m/z)		Collision Energy (eV)Transitions
(m/z)		Collision Energy (eV)
(a) dl-PCBs
PCB 81290.0 → 220.130292.0 → 222.030PCB 81L302.0 → 232.130304.0 → 234.030
PCB 77290.0 → 219.930292.0 → 222.030PCB 77L302.0 → 232.130304.0 → 234.030
PCB 123328.0 → 257.930326.0 → 255.930PCB 123L340.0 → 270.030338.0 → 267.830
PCB 118328.0 → 257.930326.0 → 255.930PCB 118L340.0 → 270.030338.0 → 267.830
PCB 114328.0 → 257.930326.0 → 255.915PCB 114L340.0 → 270.030338.0 → 267.830
PCB 105328.0 → 257.930326.0 → 255.930PCB 105L340.0 → 270.030338.0 → 267.830
PCB 126328.0 → 257.930326.0 → 255.730PCB 126L340.0 → 269.930338.0 → 267.930
PCB 167362.0 → 291.930360.0 → 289.830PCB 167L374.0 → 303.930372.0 → 301.930
PCB 156362.0 → 291.930360.0 → 290.030PCB 156L374.0 → 303.815372.0 → 301.830
PCB 157362.0 → 291.915360.0 → 290.030PCB 157L374.0 → 303.830372.0 → 301.830
PCB 169362.0 → 291.930360.0 → 289.730PCB 169L374.0 → 303.830372.0 → 302.030
PCB 189396.0 → 325.930394.0 → 324.130PCB 189L408.0 → 338.030406.0 → 336.030
PCB 70L302.0 → 232.030304.0 → 233.930
PCB 111L340.0 → 269.830338.0 → 267.830
PCB 138L374.0 → 303.930372.0 → 301.915
PCB 170L408.0 → 338.030406.0 → 336.030
(b) PCDDs/Fs
2,3,7,8-TCDF304.0 → 241.030306.0 → 242.93013C-2,3,7,8-TCDF316.0 → 252.330318.0 → 253.950
2,3,7,8-TCDD320.0 → 256.850322.0 → 193.95013C-2,3,7,8-TCDD332.0 → 268.115334.0 → 269.815
1,2,3,7,8-PeCDF342.0 → 278.830340.0 → 276.93013C-1,2,3,7,8-PeCDF354.0 → 290.215352.0 → 287.930
2,3,4,7,8-PeCDF342.0 → 278.930340.0 → 276.93013C-2,3,4,7,8-PeCDF354.0 → 289.730352.0 → 287.930
1,2,3,7,8-PeCDD358.0 → 294.930356.0 → 229.95013C-1,2,3,7,8-PeCDD370.0 → 306.115368.0 → 303.915
1,2,3,4,7,8-HxCDF376.0 → 313.030374.0 → 311.03013C-1,2,3,4,7,8-HxCDF388.0 → 324.115386.0 → 321.930
1,2,3,6,7,8-HxCDF376.0 → 313.030374.0 → 311.03013C-1,2,3,6,7,8-HxCDF388.0 → 324.215386.0 → 321.915
2,3,4,6,7,8-HxCDF376.0 → 312.930374.0 → 311.03013C-2,3,4,6,7,8-HxCDF388.0 → 324.030386.0 → 321.930
1,2,3,4,7,8-HxCDD392.0 → 329.015390.0 → 264.05013C-1,2,3,4,7,8-HxCDD404.0 → 276.030402.0 → 273.950
1,2,3,6,7,8-HxCDD392.0 → 329.015390.0 → 264.05013C-1,2,3,6,7,8-HxCDD404.0 → 276.130402.0 → 273.950
1,2,3,7,8,9-HxCDD392.0 → 329.015390.0 → 264.05013C-1,2,3,7,8,9-HxCDF388.0 → 323.815386.0 → 321.830
1,2,3,7,8,9-HxCDF376.0 → 312.930374.0 → 310.93013C-1,2,3,7,8,9-HxCDF388.0 → 323.815386.0 → 321.830
1,2,3,4,6,7,8-HpCDF410.0 → 347.030408.0 → 344.93013C-1,2,3,4,6,7,8-HpCDF422.0 → 357.850420.0 → 356.130
1,2,3,4,6,7,8-HpCDD426.0 → 361.030424.0 → 363.03013C-1,2,3,4,6,7,8-HpCDD438.0 → 373.930436.0 → 372.030
1,2,3,4,7,8,9-HpCDF410.0 → 346.930408.0 → 345.03013C-1,2,3,4,7,8,9-HpCDF422.0 → 358.130420.0 → 356.030
OCDD458.0 → 395.030460.0 → 397.01513C-OCDD470.0 → 406.130472.0 → 408.230
OCDF442.0 → 378.930444.0 → 381.03013C-OCDD470.0 → 406.130472.0 → 408.230
13C-1,2,3,4-TCDD332.0 → 267.915334.0 → 269.815
13C-1,2,3,7,8,9-HxCDD404.0 → 276.130402.0 → 273.950
Table 2. Recoveries a (%) of dl-PCBs and PCDDs/Fs congeners based on the elution rate (mL/min) in the Florisil micro-column.
Table 2. Recoveries a (%) of dl-PCBs and PCDDs/Fs congeners based on the elution rate (mL/min) in the Florisil micro-column.
Congener1 mL/min5 mL/min10 mL/min
dl-PCB
Fraction b		PCDD/F
Fraction c		dl-PCB
Fraction		PCDD/F
Fraction		dl-PCB
Fraction		PCDD/F
Fraction
dl-PCBs
PCB 81100.0 ND d99.80.298.91.1
PCB 77100.0 ND99.60.495.84.2
PCB 123100.0 ND99.90.1100.0ND
PCB 118100.0 ND99.90.1100.0ND
PCB 114100.0 ND100.0ND100.0ND
PCB 105100.0 ND99.60.499.80.2
PCB 126100.0 ND99.40.692.87.2
PCB 167100.0 ND99.90.1100.0ND
PCB 156100.0 ND99.90.1100.0ND
PCB 157100.0 ND99.90.1100.0ND
PCB 169100.0 ND97.92.175.124.9
PCB 189100.0 ND99.90.1100.0ND
PCDDs
2,3,7,8-TCDDND87.2ND77.8ND30.6
1,2,3,7,8-PeCDDND98.2ND86.1ND28.1
1,2,3,4,7,8-HxCDDND106.0ND110.7ND31.2
1,2,3,6,7,8-HxCDDND97.2ND98.6ND26.8
1,2,3,7,8,9-HxCDDND101.6ND115.0ND26.7
1,2,3,4,6,7,8-HpCDDND107.4ND107.7ND31.4
OCDDND98.1ND88.2ND26.3
PCDFs
2,3,7,8-TCDFND89.0ND84.1ND35.8
1,2,3,7,8-PeCDFND101.4ND83.2ND30.6
2,3,4,7,8-PeCDFND111.5ND100.2ND31.6
1,2,3,4,7,8-HxCDFND90.8ND83.7ND23.5
1,2,3,6,7,8-HxCDFND109.4ND94.8ND32.0
2,3,4,6,7,8-HxCDFND107.4ND100.5ND27.1
1,2,3,4,6,7,8-HpCDFND105.4ND100.4ND30.1
1,2,3,4,7,8,9-HpCDFND116.5ND97.4ND30.7
OCDFND99.3ND92.9ND27.3
a Recovery of dl-PCBs means the amount recovered from each fraction (dl-PCB and PCDD/F fractions) when the total amount of all fractions was 100% recovery. Recovery of PCDDs/Fs means the percentage of a measured concentration relative to the spiked concentration. b dl-PCB fraction: F2-F9 as shown in Figure S4. c PCDD/F fraction: F10–F12 as shown in Figure S4. d ND: Not detected.
Table 3. Calibration, method detection limit (MDL), limit of quantification (LOQ) and recoveries of target (a) dl-PCBs and (b) PCDDs/Fs.
Table 3. Calibration, method detection limit (MDL), limit of quantification (LOQ) and recoveries of target (a) dl-PCBs and (b) PCDDs/Fs.
CongenerCalibrationAvg.
RRF		MDL a
(pg/g)		LOQ b
(pg/g)		Low Conc. QC SampleMedium Conc. QC SampleHigh Conc. QC Sample
Conc. Range (pg/µL)R2Conc.
(pg/g)		Recovery ± RSD (%)Conc.
(pg/g)		Recovery ± RSD (%)Conc.
(pg/g)		Recovery ± RSD (%)
(a) dl-PCBs
PCB 810.05–2000.99991.07060.2580.8231.2586.4 ± 12.812583.5 ± 3.2125088.9 ± 3.2
PCB 770.05–2000.99991.08090.1610.5131.2592.0 ± 11.412586.7 ± 2.6125085.4 ± 3.1
PCB 1230.05–2000.99991.02810.2220.7081.2596.5 ± 4.412586.9 ± 0.8125090.1 ± 3.0
PCB 1180.05–2000.99991.10900.2330.7411.25104.3 ± 4.512588.8 ± 1.6125085.2 ± 3.6
PCB 1140.05–2000.99990.91700.2110.6711.2593.1 ± 7.912586.3 ± 1.3125093.8 ± 3.1
PCB 1050.05–2000.99990.89210.3751.1951.25106.5 ± 9.712594.9 ± 6.7125090.7 ± 3.3
PCB 1260.05–2000.99991.02340.2290.7291.2594.1 ± 4.312586.3 ± 1.1125092.6 ± 2.9
PCB 1670.05–2000.99990.96690.2180.6941.25105.2 ± 6.712585.8 ± 2.8125087.6 ± 3.2
PCB 1560.05–2000.99991.07200.3311.0541.25104.2 ± 11.512588.7 ± 3.6125097.8 ± 2.9
PCB 1570.05–2000.99991.05650.2890.9201.2599.1 ± 6.112584.9 ± 0.4125093.7 ± 3.0
PCB 1690.05–2000.99990.87490.3130.9961.2590.9 ± 6.712593.5 ± 5.6125095.3 ± 3.7
(b) PCDDs/Fs
2,3,7,8-TCDF0.05–401.00002.10090.2280.72712.588.6 ± 1.812590.4 ± 3.2125087.6 ± 0.2
2,3,7,8-TCDD0.1–400.99980.53160.3221.0261.25109.0 ± 0.812.597.3 ± 1.912590.1 ± 4.9
1,2,3,7,8-PeCDF0.25–2001.00000.98090.2150.68462.595.4 ± 1.012589.9 ± 0.2125088.3 ± 0.4
2,3,4,7,8-PeCDF0.25–2001.00001.10261.0163.23612.592.6 ± 1.762589.8 ± 1.26250101.1 ± 4.4
1,2,3,7,8-PeCDD0.25–2000.99991.13550.2730.86862.594.5 ± 1.862589.7 ± 0.8125091.3 ± 3.4
1,2,3,4,7,8-HxCDF0.25–2000.99981.39210.7612.42562.593.8 ± 1.062591.0 ± 0.96250101.5 ± 3.8
1,2,3,6,7,8-HxCDF0.25–2001.00001.36470.8492.70462.598.2 ± 2.362595.6 ± 1.3625099.2 ± 3.8
2,3,4,6,7,8-HxCDF0.25–2000.99981.25991.0713.4162.592.8 ± 2.462589.8 ± 1.36250102.1 ± 4.5
1,2,3,4,7,8-HxCDD0.25–2000.99991.06250.2510.79912.590.8 ± 2.912590.0 ± 1.1125091.4 ± 2.7
1,2,3,6,7,8-HxCDD2.5–2001.00000.97120.8622.74412.589.3 ± 2.712589.4 ± 6.9125087.1 ± 2.0
1,2,3,7,8,9-HxCDD0.25–2000.99921.82551.0453.32712.595.7 ± 7.4125103.3 ± 4.3125094.3 ± 2.5
1,2,3,7,8,9-HxCDF0.25–2001.00000.84190.5271.67812.591.2 ± 4.012596.3 ± 1.6125088.5 ± 3.3
1,2,3,4,6,7,8-HpCDF0.25–2001.00000.98891.1123.54312592.9 ± 1.1125091.3 ± 1.112,500105.3 ± 2.9
1,2,3,4,6,7,8-HpCDD0.25–2000.99990.91201.4234.53112592.9 ± 1.7125091.3 ± 0.912,50094.2 ± 4.7
1,2,3,4,7,8,9-HpCDF0.25–2000.99970.85850.6261.99312.593.2 ± 2.612590.8 ± 1.8125087.8 ± 4.3
OCDD0.5–4000.99991.04930.5711.81912597.2 ± 2.8125092.2 ± 0.712,50090.2 ± 2.5
OCDF0.5–4000.99921.16920.8532.718125101.0 ± 3.0125095.3 ± 1.912,500100.8 ± 4.9
a MDL = SD × t (n − 1, 1 − α = 0.99), t (6, 0.99) = 3.14 (n = 7). b LOQ = SD × 10.
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Chu, H.; Jo, J.; Son, Y.; Lee, J.Y.; Ahn, Y.G. Developing an Improved Strategy for the Analysis of Polychlorinated Dibenzo-p-Dioxins/Furans and Dioxin-like Polychlorinated Biphenyls in Contaminated Soils Using a Combination of a One-Step Cleanup Method and Gas Chromatography with Triple Quadrupole Mass Spectrometry. Toxics 2023, 11, 738. https://doi.org/10.3390/toxics11090738

AMA Style

Chu H, Jo J, Son Y, Lee JY, Ahn YG. Developing an Improved Strategy for the Analysis of Polychlorinated Dibenzo-p-Dioxins/Furans and Dioxin-like Polychlorinated Biphenyls in Contaminated Soils Using a Combination of a One-Step Cleanup Method and Gas Chromatography with Triple Quadrupole Mass Spectrometry. Toxics. 2023; 11(9):738. https://doi.org/10.3390/toxics11090738

Chicago/Turabian Style

Chu, Haena, Jungmin Jo, Younggyu Son, Ji Yi Lee, and Yun Gyong Ahn. 2023. "Developing an Improved Strategy for the Analysis of Polychlorinated Dibenzo-p-Dioxins/Furans and Dioxin-like Polychlorinated Biphenyls in Contaminated Soils Using a Combination of a One-Step Cleanup Method and Gas Chromatography with Triple Quadrupole Mass Spectrometry" Toxics 11, no. 9: 738. https://doi.org/10.3390/toxics11090738

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop