Gas chromatographic analysis of polychlorinated dibenzo-p-dioxins and dibenzofurans

Urban air PCDD/Fs: Dry deposition fluxes and mass transfer coefficients determined using a water surface sampler

Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) cause significant environmental concerns. Atmospheric PCDD/Fs permeate water bodies and other ecosystems through wet and dry deposition. In an urban site, dry deposition flux samples of gaseous phase PCDD/Fs were collected by a water surface sampler (WSS) operated between June 2022 and June 2023. There is a conspicuous absence of literature on the direct measurement of dry deposition flux levels in the gaseous phase of PCDD/Fs. In the study, PCDD/Fs in the gas phase reaching the WSS dissolved in the water according to Henry's Law. The PCDD/Fs in the water were transferred to an XAD-2 resin column, sorbing the dissolved PCDD/Fs. The average monthly gas phase dry deposition flux was 34.07 ± 9.35 pg/m2-day (7.35 ± 2.16 pg I-TEQ/m2-day). The highest flux was measured in March (49.53 pg/m2-day), and the lowest was in August (18.64 pg/m2-day). These values indicated the direct flux from air to water. The atmospheric concentration of the gas-phase ranged from 68.38 to 126.88 fg/m3 (13.22-25.01 fg I-TEQ/m3). Dry deposition fluxes and concentrations of atmospheric PCDD/Fs were bigger in the colder months than in the warmer months. This was probably due to a significant increase in residential heating during the colder months, decreased photochemical reactions, and lower mixing heights. Regarding congeners in the dry deposition flux and concentration values in I-TEQ units, 2,3,7,8-TCDD compound predominated with the proportions of 31.61 ± 7.76% and 29.09 ± 12.34%, respectively. Concurrently measured dry deposition flux (Fg) and ambient air concentration (Cg) of PCDD/Fs were considered in the determination of mass transfer coefficient (MTC = Fg/Cg) calculation for each PCDD/F congener. The average MTC for targeted 17 PCDD/Fs was 0.45 ± 0.15 cm/s, and it fluctuated between 0.89 ± 0.30 cm/s for 2,3,7,8-TCDF and 0.2 ± 0.16 cm/s for OCDD.

Spatial variation of PCDD/F and PCB emissions and their composition profiles in stack flue gas from the typical cement plants in China

Cement production processes are important sources of unintentionally produced persistent organic pollutants (UP-POPs), such as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), and polychlorinated biphenyls (PCBs). The emissions of PCDD/Fs and PCBs in the stack flue gases from eight typical cement plants in China were investigated in this study, including one wet process rotary kiln, three dry process rotary kilns and four vertical shaft kilns. PCBs exhibited relatively higher mass concentrations with the dioxin-like (dl) and indicator PCBs of 0.14-17.36 and 0.42-12.90 ng/Nm³, respectively. However, PCDD/Fs contributed most to the total toxic equivalent concentrations, with the proportions exceeding 90%. The international toxicity equivalency (I-TEQ) concentrations of PCDD/Fs varied greatly from 0.01 to 0.46 ng I-TEQ/Nm³ in stack gases, two of which exceeded the exhaust gas concentration limit of 0.1 ng I-TEQ/Nm³ established by the European Union Directive. In weight units, 1,2,3,4,6,7,8-HpCDF was the most abundant congener in the stack gases from various types of cement kilns, with the factions of 17.0-27.8%. TCDFs and PeCDFs were the first two most abundant homologue groups. 2,3,4,7,8-PeCDF was the largest contributor to the total I-TEQ. The emission factors of PCDD/Fs and PCBs in the eight cement kilns were estimated to be 0.01-1.35 μg I-TEQ/t clinker and 8.20 × 10^-4∼8.23 × 10^-2 μg World Health Organization TEQ (W-TEQ)/t clinker, respectively. No obvious differences of the PCDD/F and PCB emission factors were found among the varied cement production technologies.

Simple and rapid determination of PCDD/Fs in flue gases from various waste incinerators in China using DR-EcoScreen cells

In developing countries such as China, there is a strong need for simple and rapid bioassays for the determination of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in environmental samples; i.e., flue gas and fly ash from waste incinerators. In this study, we applied the DR-EcoScreen cell (DR-cell) assay to determination of PCDD/Fs in 78 flue gas samples obtained from various waste incinerators in China between 2009 and 2011. The flue gas samples were obtained from four kinds of incinerators, classified into hazardous, medical and municipal-solid waste, and iron ore sintering, and the flue gas extracts were cleaned up using an SPD-600 automated-sample preparation device for DR-cell assay. The PCDD/Fs values obtained from the DR-cell assay were compared with those obtained from conventional high resolution gas chromatography-high resolution mass spectrometry (HRGC-HRMS) analysis. The bioanalytical equivalent (BEQ) values obtained from the DR-cell assay were very closely correlated with the international toxicity equivalent (I-TEQ) values from HRGC-HRMS analysis (r2=0.98, n=78), while the BEQ values were 5.52-fold higher than the I-TEQ values, as the PCDFs, which account for 80% of the total I-TEQ value, were overestimated by DR cell-assay. Therefore, we multiplied the BEQ values from the DR-cell assay by a conversion coefficient (0.181, the reciprocal of 5.52), and could approximate the TEQ values from the HRGC-HRMS analysis. These results suggest that the DR-cell assay combined with SPD-600 cleanup provides a promising method for the simple and rapid screening of PCDD/Fs levels in flue gas samples, such as those from various waste incinerators in China.

Analysis of Polychlorinated Dibenzo-p-Dioxins and Polychlorinated Dibenzofurans in Soil and Sediment

This review presents methods for the analysis of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), called dioxins, in soil and sediment. These compounds are produced as by-products of different combustion processes, and because of their persistency and toxicity they present a threat for animal and human health. Due to their high organic matter content, soil and sediment can accumulate dioxins and have become important secondary emission sources. Determining dioxins in these samples is complex because dioxins are present in trace levels and have to be separated from interferences whereas other classes of organic contaminants are present in higher concentrations. After sampling, follows extraction of compounds with a suitable solvent, extract clean-up from unwanted compounds, and qualitative and quantitative analysis. At the end of this review, we gave levels of PCDD/PCDFs found in soil and sediment samples.

Emission of PCDD/Fs and dioxin-like PCBs from metallurgy industries in S. Korea

The metallurgy industry and municipal waste incinerators are considered the main sources of polychlorinated dibenzo-p-dioxin and dibenzofurans (PCDD/Fs) in many countries. This study investigated the emission factors and total emissions of PCDD/Fs and dioxin-like polychlorinated biphenyls (PCBs) emitted from metallurgy industries (including ferrous and nonferrous foundries) in Korea. The toxic equivalency (TEQ) emission factor of PCDD/Fs was the highest for secondary copper production, at 24451 ng I-TEQ/ton. The total estimated emissions of PCDD/Fs from these sources were 35.259 g I-TEQ/yr, comprising 0.088 g I-TEQ/yr from ferrous foundries, 31.713 g I-TEQ/yr from copper production, 1.716 g I-TEQ/yr from lead production, 0.111 g I-TEQ/yr from zinc production, and 1.631 g I-TEQ/yr from aluminum production. The total estimated annual amounts of dioxin-like PCBs emitted from these sources were 13.260 g WHO-TEQ/yr, comprising 0.014 g WHO-TEQ/yr from ferrous foundries, 12.675 g WHO-TEQ/yr from copper production, 0.170 g WHO-TEQ/yr from lead production, 0.017 g WHO-TEQ/yr from zinc production, and 0.384 g WHO-TEQ/yr from aluminum production. The highest emission factor was found for secondary copper smelting, at 9770 ng WHO-TEQ/ton.

Rapid screening method for determination of PCDDs and PCDFs in fly ashes using GC-ion trap MS/MS based on cellular disruptor extraction

Identification and quantification of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in fly ashes from incinerator was carried out using capillary gas chromatography/tandem mass spectrometry (GC/MS/MS) with a low resolution ion trap mass spectrometer. Sample extraction was carried out in a cellular disruptor, in Soxhlet and in a conventional ultrasound for comparative purposes. Extraction with cellular disruptor was shown to be comparable to that obtained by the reference Soxhlet extraction, while low recoveries were observed with ultrasound. Hospital incinerator ashes, extracted by cellular disruptor and Soxhlet presented I-TEQ values for polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans of 370 +/- 81 ng g(-1) and 533 +/- 55 ng g(-1), respectively, statistically equivalent according to the t-test.

Determination of musk compounds in sewage treatment plant sludge samples by solid-phase microextraction

Headspace solid-phase microextraction, followed by GC-MS analysis is presented as a suitable technique for the determination of musk compounds in sewage treatment plant sludge. Five polycyclic musks (celestolide, phantolide, traseolide, galaxolide and tonalide) and four nitro musks (musk xylene, musk moskene, musk tibetene and musk ketone) were considered in the optimisation of the analytical method. The influence of extraction temperature, fibre coating, agitation, pH and salting out on the efficiency of the extraction along with the extraction kinetics were studied. An extraction temperature of 100 degrees C and sampling the headspace over the stirred sludge sample using polydimethylsiloxane -divinylbenzene as fibre coating lead to effective extraction. The method proposed is very simple and yields high sensitivity, good linearity and repeatability for all the analytes with limits of detection at the sub-ng/g level. The total analysis time, including extraction and GC analysis, was only 40 min, and no manipulation of the sample was required.

Application of GC-MS/MS for the analysis of PCDD/Fs in sewage effluents

The application of high resolution gas chromatography in combination with tandem mass spectrometry in an ion trap was tested to substitute the expensive high resolution mass spectrometry in analysing polychlorinated dibenzo-p-dioxins and furans in sewage effluents. In tandem mass spectrometry, a set of parameters has to be optimised in order to attain the required sensitivity. To the best of our knowledge, this is the first time a method development for analysing PCDD/Fs with GC-MS/MS in an ion trap is described in this detail. Nine parameters are varied, including isolation window, collision induced dissociation (CID) amplitude, CID time, acquisition mass range, broadband amplitude, CID bandwidth, modulation range, filament current and ion trap temperature. This technique can be adapted to other analytes. By this optimisation, limits of detection of 0.01-0.05 ng/l are obtained. With its selectivity and sensitivity, tandem mass spectrometry is a powerful tool for the determination of PCDD/Fs in water samples. 55 sewage effluent samples from Germany were analysed.