Evaluation of an alternative extraction method of PCDD/Fs from flue gas samples
Flavia Cornea
Flavia Cornea
Master Thesis 45 ECTS Report passed:
Supervisors: Lisa Lundin, Eva Weidemann Examiner: Lars Backman
Abstract
Soxhlet has been known to be the traditional method for extracting material from solid samples. It is a well-used method for extracting polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans and very much accurate. It is, however, not a very
“green” way of approach because it uses large amounts of hazardous and flammable solvent, like toluene. It is not economical either, nor short-timed. Because of these reasons, the same extractions have been done with both Soxhlet and pressurized liquid extraction, to make a comparison between the two methods. The thesis contains two experimental parts in which Soxhlet used toluene and PLE other three solvents. Part II is about optimizing the PLE with heptane by trying different parameters that could solve some problems encountered in the first part. The results showed that PLE using heptane as solvent, extraction temperature of 150 °C and 5 extraction cycles, obtained a recovery for low and high chlorinated PCDD/Fs of 98,9%. This shows that this PLE method is as efficient as the traditional extraction method using Soxhlet with toluene as the extraction solvent. However, the low chlorinated congeners showed some differences in recoveries than high chlorinated ones.
II List of abbreviations and definitions
Analytes
DDs dibenzo-p-dioxins
DFs dibenzofurans
PCDDs polychlorinated dibenzo-p-dioxins PCDFs polychlorinated dibenzofurans
2-MoCDF mono-chlorinated dibenzofuran with chlorine substitution in position 2
2-MoCDD mono-chlorinated dibenzodioxin with chlorine substitution in position 2
Equipment, chemicals and materials
ASE accelerated solvent extractor
DCM/cyclohexane mixture of dichlormethane and cyclohexane (1:1)
HEP heptane
HEP+DCM mixture of heptane and dichlormethane (1:1) no fz samples were not freeze dried
PLE pressurized liquid extraction
PLE HEP pressurized liquid extraction using heptane as solvent
PLE HEP+DCM pressurized liquid extraction using a mixture of heptane and dichlormethane 1:1 as solvent
PLE TOL pressurized liquid extraction using toluene as solvent PUFP polyurethane foam plug
SOX soxhlet
SOX TOL soxhlet extraction using toluene as solvent SPE-disk solid phase extraction disk
TOL toluene
Definitions
Analyte chemical compound that is of interest in an analytical experiment
Congeners related chemical substances in function, origin or structure EEA-33 the 33 European countries that are part of the European Environment Agency
High chlorinated tetra- to octa-chlorinated dibenzo-p-dioxins and dibenzofurans Low chlorinated mono- to tri-chlorinated dibenzo-p-dioxins and dibenzofurans
Prefixes
mono- substitution with one chlorine di- substitution with two chlorines tri- substitution with three chlorines tetra- substitution with four chlorines penta- substitution with five chlorines hexa- substitution with six chlorines hepta- substitution with seven chlorines octa- substitution with eight chlorines
III
Contents
Abstract ...I
1. Introduction ... 1
1.1. Origins of PCDD/Fs... 1
1.1.1. Formation from precursors... 1
1.1.2. De novo formation ... 1
1.2. Methods of investigation... 1
1.2.1. Sampling ... 1
1.2.2. Soxhlet... 2
1.2.3. Pressurized liquid extraction ... 3
1.2.4. Solvents ...4
1.3 Toxicity and impact on health... 4
1.3 Aim of the study... 5
2. Popular scientific summary including social and ethical aspects ... 5
2.1 Popular scientific summary... 5
2.2 Social and ethical aspects... 5
3. Method ... 6
3.1 Chemicals and equipment ... 6
3.2. Cleaning PUFs ... 6
3.3. Filtration... 6
3.4. Extraction ... 7
3.5. Sample clean-up ... 8
3.6. Part I: Evaluation of extraction with Soxhlet and PLE ... 8
3.7. Part II: optimization of extraction with PLE... 11
3.8. Analysis on GC-HRMS and quantification ... 11
4. Results and Discussion ... 12
4.1. Part I ... 12
4.1.1. Amount of natives... 12
4.1.2. Recovery of IS... 13
4.2 Part II ... 13
4.2.1. Amount of natives ... 13
4.2.2. Recovery of IS ... 14
4.3. Comparison between heptane extracted sets of samples ... 15
5. Conclusions ... 19
6. Acknowledgements ... 19
References ... 20
Appendix A ... 22
Appendix B ... 24
Appendix C ... 32
IV
1
1. Introduction
A smart way of giving purpose to municipal solid waste (MSW) is to use it as a fuel, instead of letting it decay on landfills. Waste-to-energy plants incinerate MSW to produce energy and it is categorized as renewable energy [1]. Although it is a cleaner and more economical way of producing energy it also brings along consequences.
Industrial combustion of MSW releases different toxic bi-products and some of them are PCDD/Fs (polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans), also known simply as dioxins. These compounds are persistent organic pollutants (POPs) and present a threat to the human health [2]. During the years, there have been taken many measures to lower the levels of dioxin pollution and in 2011, a decrease of 84% in dioxins and furans emissions was reported in the EEA-33 countries, compared with the levels in 1990 [3].
1.1. Origins of PCDD/Fs
PCDD/Fs forms through two formation pathways, either through a homogeneous reaction at temperature ranging between 500 and 800 °C in gas phase, or a heterogeneous reaction at between 200 and 400 °C on solid surfaces like fly ash [4].
Many studies have agreed that the main pathway of formation for PCDD/Fs is through the surface formation and it holds two important catalytic processes. The first one is known as the precursor route where chlorobenzenes and chlorophenols react catalytically on the solid surface [5]. The second pathway of formation is called de novo route where PCDD/Fs are formed because of the presence of residual carbon in fly ash or intermediates like PAHs [6].
1.1.1. Formation from precursors
Tuppurainen et al (1998) stated that the main route of PCDD/Fs formation is through precursors like chlorobenzene and chlorophenols [7]. Precursors can be found in the fuel, forming during combustion or after combustion by going through many reactions such as ring-closure and chlorination of aliphatic compounds [8]. They are very often found in incinerator dust and chimney gas along with PCDD/Fs and many studies proved that this is why they represent the main precursors [9][10].
1.1.2. De novo formation
A small amount of carbon will stay in the ash matrix even if extracted and some carbon still remains bounds to catalytic sites in the matrix and reacts with the oxygen from the air that is flowed through the ash bed and thus breaking aromatic rings [11]. Studies have shown that in the post-combustion zone there is a transfer of chlorine from the metal chloride ligands which are incorporated in the fly ash, to the aromatic carbon rings. The reactions are catalyzed in most cases by copper which leads to PCDD/Fs formation [12].
1.2. Methods of investigation 1.2.1. Sampling
Full scale sampling of flue gas can be done through several methods like sampling system for wet flue gases from CO2-absorber, sampling by condensation of flue gas stream, multiple component sampling system or EN 1948:1 cooled probe method [13][14]. For the EN 1948:1 cooled probe method, one needs a sample train (fig. 1) consisting of a water-cooled glass probe, one glass bottle containing water and another one containing ethylene glycol, two polyurethane foam plugs (PUFPs), an aerosol filter placed between the PUFPs and a vacuum pump [15].
2 Using a water cooled probe when sampling flue gas will decrease the risk of unwanted PCDD/Fs formation within the sampling equipment. As an extra measure, the whole sampling train is held on ice to make sure that no reformation of the contaminants is going to occur. The probe is inserted in a flue gas pipe and samples are taken directly from the source, pumped through the water, glycol and an aerosol filter and the PUFPs, in order to retain particles and other impurities. An isotope labeled spike is added to make up for losses during sampling. It is added to the water bottle, before the sampling starts and it contains 37Cl 2,3,7,8-TeCDD and 1 3C 1,2,3,4,6,7-HxCDD.
Had the full scale sampling been done, it would have been sampled before the filters in the plant, in order to see what is actually formed during the combustion and in the post- combustion zone, for understanding the formation of PCDD/F in the power plant. A volume was not set because, as said before, the full scale sampling was not done.
Figure 1. Flue gas sampling train 1.2.2. Soxhlet
The Soxhlet apparatus (fig. 2) is an extraction equipment that was intended to be used for lipids in solid samples but its limits do not stop at just lipids, in the case of this thesis work, it is very much suitable for extraction of PCDD/Fs as well [16]. It is mostly used if the analytes are not greatly soluble in solvents and the impurities are insoluble.
Figure 2. Soxhlet extraction apparatus
3 The solid samples are placed inside the main glass container of the Soxhlet, along with a water separator, which is set onto a round bottomed flask, containing the solvent.
After a condenser is put on top of the container, the flask is put to heat, which w ill result into a reflux and fill the glass chamber with solvent. The role of the condenser is to drip back cooled solvent vapor, to the container where the samples are. Then the compounds of interest will dissolve in the heated solvent. The reflux can go on with no problems for several hours, the glass chamber contains a siphon which empties the solvent when it is full, into the flask. It takes a few cycles to capture all the compounds to the desired concentration. When the extraction is over, the extracts are evaporated with the rotary- evaporator and the solid samples are discarded [17][18].
1.2.3. Pressurized liquid extraction
Another method of extraction which gains popularity is pressurized liquid extraction (PLE) (fig. 3). It works on the same principle as Soxhlet but considered more efficient because of the supercritical temperature reach and pressure are at high levels, resulting in greater extraction [19][20].
Figure 3. ASE 200 for pressurized liquid extraction
PLE can be set to either a dynamic setup or a static setup. In the dynamic setup, solvent is pumped in stainless steel cells (fig. 4) which contain the solid samples, without stopping, into the glass bottles where the extracts are collected. In the static setup the extraction is done through several cycles [21]. The samples are put as they are into the cells and for the usage of even less solvent, the PLE cells are filled with glass beads or sand.
4 Figure 4. PLE stainless steel cell
The parameters of the extraction can be modified as desired. Temperature can go very high (from room temperature to 250 °C) and the number of cycles can also be varied.
Elevated temperatures increases solubility of the samples while reaching a high diffusion rate, and the increased pressure also helps the solvent not to evaporate.
Although Soxhlet is considered as the traditional method, PLE is more efficient when it comes to time and hazard related reasons. While the Soxhlet method will always be a good option, it also is time consuming and very costly because of all the required solvent. Solvents like toluene are highly hazardous and also flammable, thus it is necessary to find ways of using it less, or finding a replacement solvent with very similar strength. PLE on the other hand, is in some ways different from the traditional extraction method. Replacing Soxhlet with PLE for PCDD/Fs investigation will not just decrease solvent usage and the risk of a hazard but will also reduce the cost of the experiments and the time conducting them [22].
1.2.4. Solvents
Choosing a solvent for extracting PCDD/Fs has to be done carefully, keeping in mind that they are at trace level and their matrix is of a higher complexity and it can create difficulties. Very polar solvents can co-extract other compounds that are not of
interest but are very soluble in highly polar solvents and might give confusing results.
Toluene is a common and effective solvent that is often used for extraction, despite its hazardous and flammable potential. It is considered a non-polar solvent (2.4-
dielecrtric constant) not as polar as dichlormethane (9.1) which is considereded
“borderline” polar and very close to polarity to heptane (1.9). Non-polar solvents have a negative side as well, they might not extract the compounds with high efficiency [23][24].
1.3 Toxicity and impact on health
There are 75 dioxin congeners and 135 furan congeners, of which 17 are toxic but especially one has gotten attention the most: 2,3,7,8-TeCDD. The cause of its toxicity is due to its affinity of binding to the aryl hydrocarbon receptor [25].
PCDD/Fs have shown to cause cancer in laboratory animals. In humans, it affects the reproductive system, weakens the immune system and cause different sorts of cancer.
5 It may also cause rashes, weight loss, fatigue, decreased libido, altered glucose metabolism and neurological damage, if exposed to large amounts [26].
1.3 Aim of the study
This study work is concentrated on finding an alternative method of extracting PCDD/Fs from flue gas samples which could replace the traditional Soxhlet extraction.
Reasons behind this try are time, hazard and cost related. These three can be reduced significantly with PLE.
Evaluating different solvents was also an important part of this work. This way, another solvent which holds very similar properties can be found and used as a replacement for toluene which is used in big quantities for Soxhlet and is known as hazardous and highly flammable.
2. Popular scientific summary including social and ethical aspects
2.1 Popular scientific summary
Polychlorinated dibenzodioxins (PCDDs) and dibenzofurans (PCDDFs), or for short dioxins and furans, are very toxic contaminants that are found in the industrial chimney smoke, also called flue gas. The process of checking the levels of these dioxins and furans is expensive and it takes a lot of time and requires large amounts of hazardous chemicals, and this thesis work aims to find a quicker, safer and cheaper way of checking those levels. First of all, samples must be taken and in this case, flue gas samples are the ones which were tested. Although an actual sampling did not take place during this work, “fake samples” prepared in the laboratory were analyzed, which are very much the same as real samples. This is because they were added the same contaminants that are found in flue gas. The only difference between them is that these lab-made samples are very clean and do not have any other chemical compounds in their composition that might affect the experiments. The samples consists of polyurethane foam plugs which look like sponges, and different types of filters which were purposely contaminated with PCDDs and PCDDFs.
The technique investigated is called pressurized liquid extraction or PLE for short. It works on the same principles as the traditional method (Soxhlet), which is practically transferring the dioxins and furans you have in your samples, to a substance which we call a solvent, to make it possible to do measurements on. At a certain temperature and pressure, the solvent will go through the samples and steal away the dioxins and furans.
That is called an extraction. This way your samples will have a liquid form and will be possible to analyze. After this step, your sample might have been slightly contaminated because of some other chemicals in the foam plugs that are released during extraction or from some other sources in the lab. This is why a clean-up of the samples is required.
Cleaning them will assure us that the samples will only contain the dioxins and furans.
After the samples have been gone through those steps, they are still not ready for analysis. They still contain a lot of solvent so that is why an evaporation step is done.
The solvent will evaporate if the sample is heated up, and all that will be left are the compounds of interest. The small volume of the sample is put in a small glass vial and analyzed with the help of gas chromatography (GC) and mass spectrometry (MS). These two are analytical techniques which help separating the dioxins and furans into individual components (GC) and then identify them (MS). With the data that we get from the GC-MS, calculations can be done to find out in what amount these PCDD/Fs are released in the environment.
2.2 Social and ethical aspects
In the case of this thesis work, there are no ethical aspect that can be discussed. From this work, we can say that the working environment could be safer due to the findings of this research. Working with less toxic and less dangerous chemicals can impact one’s activity in the lab, not to mention their health and by preserving solvents, less damage will be released in the environment.
6
3. Method
3.1 Chemicals and equipment
The solvents used were purchased from the University’s own chemistry storage and provided by SIGMA-ALDRICH. These were toluene, heptane and a mixture of heptane and dichlormethane 1:1 and were described in the introduction. Toluene is a non-polar substance and was chosen because it is a very common solvent to work with when doing extractions, especially for Soxhlet. It was also used for PLE to be able to compare results.
Heptane is even more non-polar than toluene and was chosen for PLE. The polarity of dichlormethane is much higher than the ones previously mentioned and it was proven in some studies that mixtures sometimes extract even better than non-mixed solvents.
Cleaning of the PUFPs required toluene and acetone.
A mixture of water and glycol was needed to simulate the full scale sampling and it was used in the filtration part.
HCl was used to acidify the water/glycol mixture before the second filtration and methanol for soaking the SPE-disk.
Hexane was used to wash the silica columns, and the Super ALOX columns were eluted with dichlormethane/cyclohexane 1:1.
For sample clean-up, the small columns contained KOH-silica, neutral silica, H2SO4 silica and a layer of Na2SO4, and the Super-ALOX columns were added Alumina B- Super 1 and Na2SO4. The substances were already in the laboratory.
Tetradecane (SIGMA-ALDRICH) served as a keeper substance to save the analytes from being evaporated during the evaporation step.
For evaporating the water content present in the PUFPs, they were put overnight in a freeze dryer. Dionex – ASE 200 Accelerated Solvent Extraction is the name of the machine on which pressurized liquid extraction was performed. Soxhlet apparatuses were used for both extraction and cleaning of the PUFPs.
SUPELCO evaporator uses a flow of nitrogen to evaporate the samples of remaining solvent.
QS, IS and RS are quantification, internal and recovery standards. All of them contain known amounts of compounds but differ in roles. QS is used to help calculate an unknown amount of contaminants in a sample and it contains native congeners. IS is contains very similar compounds to the natives but not the same. Recovery standard is added in case of analyte loss during extraction.
3.2. Cleaning PUFs
PUFP were cleaned using a large (2 L) Soxhlet. It was let to reflux for 16 hours under heat using toluene and after that, refluxed with acetone for approximately 6 hours, as well under heat. The PUFPs were let to dry at room temperature in a fume hood until all the solvent was evaporated.
3.3. Filtration
Filtration of the water/glycol mix was done through a vacuum as seen in figure 5. A vacuum filtration assembly was put together (figure 5) and the mixture was filtrated on two layers of filters, one was a nylon filter and one a glass microfiber filter.
7 Figure 5. Vacuum filtration apparatus
Approximately 1,5 L of water was added to the water/glycol mix to lower its viscosity and filtered through a glass fiber filter and a nylon filter.
Before a second filtration was done, the pH needed to be regulated to 2, thus 10-15 drops of HCl were added to each bottle and then checked with pH paper. The filtration went on through an ENVI-disk (solid phase extraction disk or SPE for short) which was soaked for half an hour in methanol, and half a PUFP. After the first pouring of the filtrated water/glycol, the PUFP was checked for any air bubbles before the vacuum was open. It was very important that mixture was added constantly, before it was all gone from the glassware. The SPE-disk must be, at all means wet, otherwise it will become dry and not allow water to go through. This is due to the disk’s hydrophobic material and that is why it is kept in methanol before usage, methanol is a water-miscible solvent.
After the second filtration, the glassware of the Soxhlet samples was rinsed with toluene and added to the four Soxhlet apparatuses, along with the three filters and the half PUFP. The samples for PLE were transferred in Aluminium baskets and put in the freeze dryer, overnight.
3.4. Extraction
The Soxhlet extraction was done as described in the introduction. 400 mL of toluene refluxed the PUFPs for 16 hours and then 400 mL acetone for approximately 6 hours.
PUFPs and filters were put in PLE cells, along with glass beads to occupy all the cell’s volume. After the extraction, the extracts were evaporated using the rotary-evaporator, approximately to 1 mL. The evaporated extracts were then divided in two exact amounts and put in two vials each, to have extras in case the clean-up needed to be repeated because of loss of analytes or because of further investigation on other contaminants like PCBs. The extracts were then evaporated again with the SUPELCO evaporator which runs a flow of nitrogen into the samples. Tetradecane, known also as “keeper”, was added in order for the sample not to be evaporated completely and lose analytes, as well as a splash of toluene, to slow down the evaporation and reduce losses of analytes.
8 3.5. Sample clean-up
The first type of column used was packed at the end tip with glass-wool, not too tight so that the solvent goes through but also not too loose so that the first layer of silica doesn’t fall out.
Figure 6. Flow chart of the sample column clean-up
Three layers of silica were added: 1.5 mL KOH-silica (or basic, 20%), 1 mL neutral silica (heated at 130°C) so that layer 1 and layer 2 do not react with each other, 2 mL H2SO4 silica (40%) and a layer of Na2SO4. They were washed with two times their size of hexane and then the Super-ALOX columns were added under, after packing them as well with glass-wool, 9 mL of Alumina B-Super 1 and 3 grams of Na2SO4. The extracts were added to the first columns which were connected to the Super-Alox columns and eluted with 30 mL of hexane. After this, the multi-silica columns were removed and the Super- Alox column were washed with 30 mL of hexane. After that, the Super-Alox columns were eluted with 100 mL of dichlormethane/cyclohexane (1:1) the samples were all added 1 mL of toluene for them not to evaporate completely when put in the rotary- evaporator. RS (recovery standard, see Appendix A) was also added to the samples. All were evaporated to 40 µL and put in small GC vials. A simplified flow chart is shown in figure 6.
3.6. Part I: Evaluation of extraction with Soxhlet and PLE
The first part of the experiment consisted of sixteen prepared samples, four for Soxhlet and 12 for PLE. 40 cleaned PUFPs were used in total.
Twelve samples were spiked with QS (quantification standard, see Appendix A), divided in three equal parts, one for the water/glycol and two whole PUFs. The blanks were not spiked with QS. The QS vial was also cleaned with hexane and added to one part of the sample, either one of the two PUFs, either the glass bottle with the glycol/water mixture.
To all samples, including blanks, IS (see Appendix A) was added from two capillary vials (Mono-tri PCDD/F and 4-8 PCDD/F plus planar PCB), with two needle syringes, used only for those specific IS. 40 µL were added from each IS, only to the bottles with water/glycol. The filtration step was described in 3.3.
Each sample contained a bottle of water/glycol mixture, two and a half PUFs, one nylon filter, one glass microfiber filter and one aerosol filter. 250 mL water and 200 mL glycol were added in each bottle.
9 After the filtration, the two and a half PUFs and filters of samples 1-4 were put in four Soxhlet apparatuses. The dry PUFPs were ready to go in the PLE cells but the aluminium baskets which held the other 12 (samples 5-16, 1/2 PUFP and 3 filters each) were put in the freeze dryer overnight (fig. 7).
Figure 7. Freeze dryer
The next day they were dry and stuffed in PLE cells. A prior washing of the cells was needed. An extraction with different solvents was performed on the ASE 200, as shown below in Table 1. Fort the samples that were extracted with PLE, 2 different solvents were used and a mixture of two solvents. For samples 5-8, the same solvent was used as for the Soxhlet method, which is toluene. For samples 9-12, heptane was chosen as a solvent. On samples 13-16, a mixture of heptane and dichlormethane (1:1) was used.
The clean-up step was performed as described in 3.4. Two QSs were used as reference standards for both Soxhlet and PLE, and RS and keeper were added to them too.
10 Table 1. Parameters of samples extracted with different solvents
Method Solv ent No. of samples Temperature /°C Heat
/min Static
Time /min Cy cles Rinse v olume /% Purge /s Freeze dry No. of replicates
Soxhlet Toluene 1-4 3+blank
PLE Toluene 5-8 120 6 5 3 50 60 ✔ 3+blank
PLE Heptane 9-12 120 6 5 3 50 60 ✔ 3+blank
PLE Heptane/DCM 13-16 120 6 5 3 50 60 ✔ 3+blank
11 3.7. Part II: optimization of extraction with PLE
The second part of the experiment was conducted based on the results obtained from part I and an optimization of the PLE was performed. The filtration was skipped this time, due to the fact that the samples were already clean. In the first part, no matrix was present either in the samples but the full scale sampling at Dåva waste-to-power plant was still in the schedule at that time and it was a preparatory step for the real flue gas samples. The half PUFPs and the three filters were soaked into a glycol/water mixture so that the samples from this part won’t be prepared under different conditions. A QS vial was divided between the two and a half PUFPs, for each sample. The extraction was done the same as described earlier and samples were categorized into five sets.
Table 2. Parameters used for the five sets of samples No.
of set Temperature
/°C Heat
/min Static Time /min
Cycles Rinse volume
/%
Purge
/s Freeze
dry No. of replicates
I 150 7 5 5 50 60 ✔ 3
II 180 9 5 3 50 60 ✔ 3
III 180 9 5 5 50 60 ✔ 3
IV 150 7 5 3 50 60 x 3
V 150 7 5 3 50 60 ✔ 2
In the table 2, all five sets of samples and the conditions of extraction which were varied are shown. Set I, consisting of samples 1-3, was freeze dried overnight, before being extracted under 150°C and 5 cycles. Set II of samples 4-6 was freeze dried overnight and extracted under 180°C and 3 cycles. Set III of samples 7-9 was also left in the freeze dryer overnight and extracted under 180°C but in 5 cycles. Set IV of samples 10-12 was not put to freeze dry and was extracted under 150°C and 3 cycles.
Following the extraction, the sample clean-up was performed on all samples, the same way as in part I.
3.8. Analysis on GC-HRMS and quantification
The samples were analyzed with gas chromatography coupled with high resolution mass spectrometry (GC-MS), and equipped with a 60m DB5 column. Quantification of the data was done with the help of equation I:
𝑄𝑖 12𝐶 (𝑠𝑎𝑚𝑝𝑙𝑒)= 𝑄𝑖 12𝐶(𝑟𝑒𝑓𝑠𝑡𝑑)∗𝐴𝑖 12𝐶(𝑠𝑎𝑚𝑝𝑙𝑒)
𝐴𝑖 12𝐶(𝑟𝑒𝑓𝑠𝑡𝑑)
∗𝐴𝑖 13𝐶(𝑟𝑒𝑓𝑠𝑡𝑑)
𝐴𝑖 13𝐶(𝑠𝑎𝑚𝑝𝑙𝑒)
[I]
where Qi 12C is the amount of native congener I, Ai 1 2Cis the response area for native congener I and Ai 13C is the response are for 13C1 2-labelled congener i.
The recovery of IS was calculated with the formula below, and it is used only if there are the same added amounts of IS and RS:
𝑅𝑖(%) =𝐴𝑖 13𝐶(𝑠𝑎𝑚𝑝𝑙𝑒)
𝐴𝑖 13𝐶(𝑟𝑒𝑓𝑠𝑡𝑑) ∗ 𝐴𝑖 𝑅𝑆(𝑟𝑒𝑓𝑠𝑡𝑑)
𝐴𝑖 𝑅𝑆(𝑠𝑎𝑚𝑝𝑙𝑒)∗ 100 [II]
where Ri is the recovery of IS (%), Ai IS is the response area of IS (%) and Ai RS is the response area of 13C1 2-labelled RS.
12
4. Results and Discussion
4.1. Part I
The aim of the first part of the experiments was to compare the traditional Soxhlet extraction method using toluene, to PLE using different solvents. The temperature was set to 120 °C with 3 cycles of extraction.
4.1.1. Amount of natives
As seen in the figure 8, extracting with toluene resulted in higher amounts of the native congeners, with both Soxhlet (108,7%) and PLE (102,19%). 100% represents the exact amounts added from the jar. There is almost no difference in amounts between the two methods except for the low chlorinated compounds, more specifically, the mono- chlorinated DDs and DFs. 2-MoCDF with PLE was found in a very high amount (2,38±0,28), above the standard amount (1), and 2-MoCDD at 1,73±0,17 compared to 1,15±0,04 (Soxhlet). From the high chlorinated contaminants, OCDD showed a concentration above the maximum (0.95) of 1,23±0,14. The variance between the replicates was low, standard deviations were in close ranges for the majority of the compounds (see Appendix B).
Figure 8. Overall concentrations of mono-chlorinated to octa-chlorinated dibenzo-p- dioxins and dibenzofurans, extracted with 2 different solvents and one mixture, with Soxhlet and PLE. The sample concentrations were transformed in percentages.
Toluene extracted the low chlorinated congeners better than heptane, with slightly higher concentrations (see Appendix C). The most significant one was for 2-MoCDF of 1,06±0,04 vs. 1,75±0,77. Although the concentration is significantly higher, the result might not be accurate due to the large standard deviation. Samples 9 and 10 had close concentrations (0,91 and 1,21) whereas sample 11 showed a concentration almost twice as big (2,36). These standard deviations remain high for all mono- to tri-chlorinated DDs and DFs, sample three exceeding the maximum concentration. The blank presented slightly elevated levels of native congeners which might have been because of contamination in the working environment.
The mixture (heptane/ DCM 1:1) used as a third solvent offered fair concentrations, similar to toluene but a bit over the original amounts. OCDD had an exceeded concentration of 1,44±0,12 over the standard one of 0,951. Standard deviations w ere within small ranges for all congeners. Again, low chlorinated compounds were better extracted than with toluene, especially 2-MoCDF, 2-MoCDD and 237-TriCDD.
108.07%
113.84%
102.19%
132.02%
0%
20%
40%
60%
80%
100%
120%
140%
160%
SOX TOL PLE TOL PLE HEP PLE HEP+DCM
SOX TOL PLE TOL PLE HEP PLE HEP+DCM
13 4.1.2. Recovery of IS
On an average, IS was recovered on a range between 50%-77%. SOX TOL had the highest recovery, followed by PLE TOL which was not very far away from the recovery with heptane, as seen in figure 9.
Figure 9. Overall concentrations of 13C-labelled mono-chlorinated to octa-chlorinated dibenzo-p-dioxins and dibenzofurans, extracted with 2 different solvents and one mixture, with Soxhlet and PLE.
13C 2-MoCDF was recovered very poorly (21%) with PLE TOL, as was 13C 2-MoCDD (30%). The recoveries of the other congeners using SOX TOL were above 70%-80% for most of them and were higher with approximately 10% than PLE TOL.
Recoveries for PLE HEP were somewhat similar in values for all congeners, showing no pattern of recovery between low chlorinated and high chlorinated compounds, for both furans and dioxins. They ranged between 49-69% with noticeable standard deviations.
This was due to the variance between replicates, as sample one was the only one with recoveries greater than 70% and 80%.
PLE HEP+DCM showed the lowest recoveries, not even going over 60%, except for 13C 23478-PeCDF (62%). Very low values were found for 13C 2-MoCDF and 13C 2- MoCDD of only 36% and 32%. 13C OCDF was recovered only 40%, the lowest recovery amongst the high chlorinated compounds.
The overall concentration of native congeners with heptane/DCM was over 100% which influenced the decision of continuing the second part of the experiments with heptane due to uncertainty of results. Even if heptane had the overall concentration at the lowest, it was still above 80%, more exactly 84% which is in fact a very good value.
4.2 Part II
4.2.1. Amount of natives
Part II held 14 samples (two blanks included). Given the fact that Soxhlet was formerly used and it was proven to be an effective extraction method, it was not used in this part of the experiment, with PLE being the only extraction method used. Heptane was chosen as the solvent for all 14 samples due to its efficiency in the prior set of samples (9-12) and for its lower toxicity and flammability.
Changing some of the extraction parameters is another factor that differentiates the second part from the first. By doing again an average of concentrations, it can be seen in figure 10 that all four sets of samples have very close values, all over 80%.
77%
66% 61%
50%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
SOX TOL PLE TOL PLE HEP PLE HEP+DCM
SOX TOL PLE TOL PLE HEP PLE HEP+DCM
14 Figure 10. Overall concentrations of mono-chlorinated to octa-chlorinated dibenzo-p- dioxins and dibenzofurans, extracted with the same solvent and the same extraction method (PLE). The sample concentrations were transformed in percentages.
All four sets of samples had similar amounts of native compounds for the low chlorinated (mono- to trichlorinated) contaminants, somewhere near the amounts in the jar (see Appendix C). An exception was 2-MoCDF in set IV (1,68) although the result might not be very accurate because of the high standard deviation of 0,48 (see Appendix C). It is important to mention that in the sets of samples II, III and IV, 2-MoCDD was absent. The chromatogram was unreadable because of the abundant noise, even after running the samples for a second time in the GC-MS. After the first run, there was no signal in the first set of samples either, but after the second run, the chromatogram contained a low signal, enough to be read. 2-MoCDD appeared with an amount of 1,01 (see Appendix C).
The high chlorinated (tetra- to octachlorinated) DDs and DFs were extracted remarkably well in all sets of samples, with very low standard deviations. Blanks did not present significant levels of contamination.
4.2.2. Recovery of IS
Looking at the plot in figure 11, it can be clearly seen that IS was recovered most successfully (73%) in the first set of samples, using temperature at 150 °C and 5 cycles of extraction. The other three sets of samples recovered only by half the amount of IS.
Figure 11. Overall concentrations of 13C-labelled mono-chlorinated to octa-chlorinated dibenzo-p-dioxins and dibenzofurans, extracted with the same solvent and the same method (PLE) but with changes in some parameters.
98.90%
91.86% 92.99% 99.59%
0.00%
20.00%
40.00%
60.00%
80.00%
100.00%
120.00%
140.00%
HEP 150 °C+5 cycles
HEP 180 °C+3 cycles
HEP 180 °C+5 cycles
HEP 150 °C+3 cycles (no fz)
HEP 150 °C+5 cycles HEP 180 °C+3 cycles HEP 180 °C+5 cycles HEP 150 °C+3 cycles (no fz)
73%
54% 55%
51%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
HEP 150 °C+5 cycles
HEP 180 °C+3 cycles
HEP 180 °C+5 cycles
HEP 150 °C+3 cycles (no fz)
HEP 150 °C+5 cycles HEP 180 °C+3 cycles HEP 180 °C+5 cycles HEP 150 °C+3 cycles (no fz)
15 Both low chlorinated and high chlorinated congeners were recovered noticeably better in set I, most of them ranging between 70%-87% (see Appendix C). 13C 2-MoCDF showed a recovery of 58% and an extremely low recovery of 13C 2-MoCDD (17%), which was found only in set I. There was a noticeable variance between replicates for 13C 28- DiCDF (79%±25%), 13C 248-TriCDF (82%±22%), and 13C 237-TriCDD (74%±25%). The discrepancy is seen in the first sample, having much lower recoveries for the three congeners.
Sets II, III and IV presented very similar recoveries, although much more variance can be seen in sets II and III. For set II, the difference can be seen in samples two and three, having lower recoveries than sample 1, with about 20%. 13C 2378-TCDD shows a recovery of almost 100% but with a standard deviation of ±74% because of the uncommonly high recovery in sample two (182%). Set III contains sample one which does not have any recoveries above 50%, for none of the congeners. From this point of view, set IV has low values of standard deviations but does remain at about the same level of recovery as sets II and III. Blanks did not present significant levels of contamination.
4.3. Com parison between heptane extracted sets of sam ples
At a first sight of figure 12, the results do not show a big change in the PLE method at different temperatures, compared to the initial one in the first part of the experiments.
Although they have very close values, only one was capable to produce good enough results concerning all chlorinated dibenzofurans and dibenzodioxins (see Appendix C).
Figure 12. Overall concentrations of mono-chlorinated to octa-chlorinated dibenzo-p- dioxins and dibenzofurans, extracted with the same solvent and the same extraction method (PLE). The sample concentrations were transformed in percentages and plotted against the reference standard concentration and the concentration from the first part of the experiments (HEP 120 °C+3 cycles).
Operating on a 150 °C temperature and 5 cycles using heptane, the majority of natives were able to be extracted at concentrations close to the standard ones, especially the high chlorinated ones, with small standard deviations, thus making the results more thrust-worthy. Low chlorinates natives were extracted as well close to the standard amounts, with the exception of 2-MoCDD for sets II, III and IV. An assumption of why that happened is that the temperature was too high and due to their volatility, were lost during extraction or even during evaporation with either the rotary evaporator or the nitrogen flow evaporator. If we look back at the results from the first extraction with heptane at 120 °C and 3 cycles, mono-, di- and tri-chlorinated CDDs and CDFs were found in higher amounts, meaning that the solvents co-extracted other compounds,
98.90%
91.86% 92.99% 99.59% 103.06%
0.00%
20.00%
40.00%
60.00%
80.00%
100.00%
120.00%
140.00%
HEP 150
°C+5 cycles
HEP 180
°C+3 cycles
HEP 180
°C+5 cycles
HEP 150
°C+3 cycles (no fz)
HEP 120
°C+3 cycles
HEP 150 °C+5 cycles HEP 180 °C+3 cycles HEP 180 °C+5 cycles HEP 150 °C+3 cycles (no fz)
HEP 120 °C+3 cycles
16 especially 2-MoCDD and 2-MoCDF. 2-MoCDD was probably the most volatile compound and did not resist the high temperature.
Figure 13. Overall concentrations of 13C -labelled mono-chlorinated to octa- chlorinated dibenzo-p-dioxins and dibenzofurans, extracted with the same solvent and the same method (PLE) but with changes in some parameters. The four concentrations are shown along with HEP 120 °C+3 cycles (PLE TOL).
IS recoveries only improved for PLE HEP with 150 °C and 5 cycles at 73% (figure 13), almost the same as for Soxhlet (77%, figure 2). The other sets of samples did not see any improvements, values going even lower than for 120 °C.
In figure 14 both PLE and Soxhlet are shown together to see how much of a difference in PCDF amounts exists. It is easily seen that none of the methods succeeded in extracting close to 100% (see Appendix B) of the low chlorinated PCDFs. Although it looks like Soxhlet exceeds PLE, the difference is not large and we can consider that extraction with heptane under those specific parameters worked quite successfully and almost as good as with toluene. An overall look at the standard deviations shows that PLE HEP had less variance between the replicates than SOX TOL.
Figure 14. PLE concentrations compared to Soxhlet concentrations for native PCDFs 73%
54% 55%
51%
61%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
HEP 150 °C+5 cycles
HEP 180 °C+3 cycles
HEP 180 °C+5 cycles
HEP 150 °C+3 cycles (no fz)
HEP 120 °C+3 cycles
HEP 150 °C+5 cycles HEP 180 °C+3 cycles HEP 180 °C+5 cycles HEP 150 °C+3 cycles (no fz) HEP 120 °C+3 cycles
- 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
PLE HEP 150 °C+5 cycles SOX TOL 120 °C+3 cycles
17 The same can be seen in figure 15 regarding the low chlorinated PCDDs. It can also be seen that 1234678-HpCDD and OCDD gave a closer range in values with PLE and have a small standard reviation, keeping the concentrations below or equal to the standard amount (0,5 out of 0,5 for 1234789-HpCDF and 0,95 out of 0,951 for OCDD), whereas Soxhlet showed an excess in their concentrations (0,60 for 1234678-HpCDD and 1,23 for OCDD).
Figure 15. PLE concentrations using heptane compared to Soxhlet concentrations using toluene for native PCDDs
Concerning the IS recoveries, all PCDFs were recovered over 50% with both methods, having very close recovery values.
Figure 16. IS recoveries of PCDFs with PLE using heptane and Soxhlet using toluene.
- 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
PLE HEP 150 °C+5 cycles SOX TOL 120 °C+3 cycles
0%
20%
40%
60%
80%
100%
120%
PLE HEP 150 °C+5 cycles SOX TOL 120 °C+3 cycles
18 PCDDs were recovered fairly similar with the exception of the mono-chlorinated congener.
Figure 17. IS recoveries of PCDDs with PLE using heptane and Soxhlet using toluene.
Looking at the first part of the experiments, there is no doubt that Soxhlet remains an efficient method of extraction for PCDD/Fs along with toluene. It is also clear that PLE was as good as Soxhlet, using toluene as well. The difference in amounts is insignificant and it can be affirmed that pressurized liquid extraction works as well as the traditional method. If we look at the other solvents, heptane was the solvent that came the closest to the efficiency of toluene, judging by an overall view of the extraction. The heptane/DCM mixture exceeded the jar amount of natives which it’s theoretically impossible, and obtained the lowest recoveries for IS. There are several reasons for this to happen and some assumptions would be contaminations in the working environment, for example using unwashed glassware or tweezers by mistake or presence of some solvent in the PUFPs even after freeze drying. But there was a set of samples (IV) which was not freeze dried and PUFPs were put directly as they were in the PLE cells for extraction. By the looks of the data, the presence of the solvent did not interfere very much with the amounts. DCM is a moderately polar solvent and this might be the reason that affected the extraction. Toluene and heptane are non-polar solvents and showed a better and similar extraction compared to heptane/DCM. Due to its moderate polarity, DCM might have co-extracted other compounds from the PUFPs, which are soluble in polar solvents. The possible extraction of small compounds from the PUFs could disturb the analysis of PCDD/F thus resulting in higher than expected concentrations. Amounts of native congeners were visibly higher when extracted with heptane/DCM than with toluene with PLE and Soxhlet, especially for MoCDD. IS recoveries were not as good as the natives’, heptane and heptane/DCM did not recover the congeners as good as toluene did and there’s a noticeable gap between their values.
A personal theory of why this happened is that the IS contains congeners with 13C isotope and there might be a difference in volatility or solubility between 13C and 12C.
The most probable reason for this is because of a mistake in the calculations of the equations [I] and [II]. IS value was used in equation [I] to calculate the amounts of native congeners (Qi 12C).
The second part of the experiments was held using only heptane but in different conditions. From the data it was concluded that PLE using heptane at 150 °C and 5 cycles worked best for all PCDD/Fs. It was the only method that recovered MoCDD and
0%
20%
40%
60%
80%
100%
120%
140%
PLE HEP 150 °C+5 cycles SOX TOL 120 °C+3 cycles
19 also extracted the other congeners in more than reasonable amounts. Increasing the temperature appeared to be a good choice when extracting with heptane, for both natives and IS. 1 3C-labelled PCDD/Fs were recovered much better at 150 °C than at 120
°C. The number of cycles does not appear to have a very big impact on the extraction efficiency. The recoveries were as good as with toluene, solving the IS loss problem that was encountered in the first part of the experiments.
5. Conclusions
There are several things that can be concluded after the data interpretation of this thesis work and put in a few words. Judging by the final comparison between the results of pressurized liquid extraction and the Soxhelt extraction, PCDD/Fs can be extracted with the PLE using heptane.
The data presented in this thesis work comes with a lot of answers, but questions as well. As a personal opinion, more investigations can be done on this matter.
Considering the fact that at a lower temperature using heptane, the low chlorinated congeners were recovered better than at a higher temperature, extraction of low chlorinated DD/Fs could be done separately from the high chlorinated ones, especially because of MoCDD which is the most likely compound to be lost during the process.
High chlorinated congeners can be extracted well even when using high temperatures such as 180 °C in three or five cycles with small chances to be lost during the process and so, maybe at an even higher temperature of 200 °C, concentrations and recoveries can improve a bit more. PUFPs have a high thermal resistance and will most probably not deteriorate during the extraction. Also, other non-polar solvents can be compared to more polar solvents to see if there is a difference in extraction, and this way it can also be observed if low chlorinated compounds are indeed more soluble in polar solvents.
6. Acknowledgements
I would like to thank several people for helping me throughout this thesis w ork and finishing it in time. First of all, my two supervisors Lisa Lundin and Eva Weidemann who helped me more than I realized at that time by explaining to me everything I did not understand until I finally did, and also giving me tips and ideas to finally crack some mysteries. There was a time I really thought I will not finish before the deadline but their understanding and encouragements boosted my confidence and working rhythm, especially their jokes. Thank you again and I hope I did not annoy you that much.
Secondly, all the other people who gave me extra help: Per Liljelind who spend time with me and the GC-MS when it only gave bad spectra until I got good ones, Staffan Lundstedt who always knew what was “wrong” with the ASE machine when I had no clue, Maria Hjelt, Anna Kitti-Sjöström and Marcus Östman whom I asked numerous times where I could find different things I needed to use or how to use or even open them.
I also want to thank my parents, grandmother and friends for encouraging me over the phone or the internet and for supporting me in general, it really makes a
difference.
Last but not least, I want to thank Hanh Thao Ho and Beata Dulko-Smith, my
classmates, my close friends and my “partners in suffering” as we humorously referred to ourselves. Thank you for all the discussions about everything, for the delicious food we shared for lunch and dinner in the staff room and for all the support, relaxing fikas, nice conversations and laughs whenever we felt exhausted and overwhelmed.
Thank you all!
20
References
1. Hamad, T. A., Agll, A. A., Hamad, Y . M., & Sheffield, J. W. (2014). Solid waste as renewable source of energy: current and future possibility in Libya. In Case Studies in Thermal Engineering (pp. 144-152). Missouri: Elsiver.
2. Cormier, S. A., Lomnicki, S., & Dellinger, B. (2006, June). Origin and Health Impacts of Emissions of Toxic By-Products and Fine Particles from
Combustion and Thermal Treatment of Hazardous Wastes and Materials.
Environmental Health Perspectives, pp. 810-817.
3. Luekewille, A. (2015, January 20). Persistent Organic Pollutant Emissions.
Retrieved from eea.europa: http://www.eea.europa.eu/
4. Jansson, S. (2008, November). Thermal Formation and Chlorination of Dioxins and Dioxin-Like Compounds. Umeå, Sweden.
5. Altarawneh, M., Dlugogorski, B. Z., Kennedy, E. M., & Mackie, J. C. (2007).
Mechanisms for PCDF and PCB formation from fires: Pathway from oxidation of chlorobenzenes.
6. Xhrouet, C., Pirard, C., & Pauw, E. (2001, April). De novo synthesis of polychlorinated dibenzo-p-dioxins and dibenzofurans on fly ash from a sintering process. Enivorn Sci Technol., 1616-23.
7. Tuppurainen, K., Halonen, I., Ruokojärvi, P., Tarhanen, J., & Ruuskanen, J.
(1998). Chemosphere, 1108-1113.
8. Wielgosinski, G. (2012, March). Pollutant Formation in Combustion Processes.
Advances in Chemical Engineering.
9. Thomas, p. T., Aylward, L. L., & Karch, N. J. (1997). Immunotoxicity of Dioxin:
Is the TEF Concept Premature? In V. Turoski, Chlorine and Chlorine Compounds in the Paper Industry (p. 319).
10. Stanmore, B. R. (2004, February). The formation of dioxins in combustion systems. Combustion and Flame, 136(3), 398-427.
11. Environment Australia (1999), Incineration and Dioxins: Review of Formation Processes, consultancy report prepared by Environmental and Safety Services for Environment Australia, Commonwealth, Department of the Environment and Heritage, Canberra.
12. McKay, G. (2001, August 8). Dioxin characterisation, formation and minimisation during minicipal solid waste (MSW) incineration: review.
Chemical Engineering Journal, 86, 2343-368.
13. Wittgens, B., Einbu, A., Brunsvik, A., Kolbjørn, Z., Hunnes, E., & Johansson, C.
(2010). Establish sampling and analytical procedures for potentially harmful components post combustion amine based CO2 capture. Trondheim.
14. Phan, D., Weidemann , E., Lundin, L., & Jansson, S. (2012, August). Accurate sampling of PCDD/F in high temperature flue-gas using cooled sampling probes. Chemosphere, 832-6.
15. Weidemann, E. (2010, October). PCDD/F removal capacity of fabric filters in a MSW incineration plant.
16. Luque de Castro, M. D., & Garcia-Ayuso, L. E. (1998, August). Soxhlet extraction of solid materials: an outdated technique with a promising innovative future. Analytica Chimica Acta, 369(1-2), 1-10.
17. Jensen, W. B. (2007). The Origin of the Soxhlet Extractor. Journal of Chemical Education, 84(12), 1913.
18. Soxhlet extractor. (n.d.). Retrieved from https://www.researchgate.net.
19. Mustafa, A., & Turner, C. (2011, October). Pressurized liquid extraction as a green approach in food and herbal plants extraction: A review. Analytica Chimica Acta, 703(1), 8-18.
20. Benthin, B., Danz, H., & Hamburger, M. (1999, April). Pressurized liquid extraction of medicinal plants. Journal of Chromatography A(837), 211-219.
21. Carabias-Martinez, R., Rodriguez-Gonzalo, E., Revilla-Ruiz, J., & Hernández- Méndez, J. (2005, September). Pressurized liquid extraction in the analysis of food and biological samples. Journal of Chromatography, 1098(1-2), 1-17.
21 22. Cardenas-Toro, F. P., Alcázar-Alay, S. C., Coutinho, J. P., Godoy, H. T.,
Forster-Carneiro, T., & Meireles, M. A. (2015, April). Pressurized liquid extraction and low-pressure solvent extraction of carotenoids from pressed palm fiber: Experimental and economical evaluation. Food and Bioproducts Processing, 94, 90-100.
23. Gao, Q., Haglund, P., Pommer, L., & Jansson, S. (2015). Evaluation of solvent for pressurized liquid extraction of PCDD, PCDF, PCN, PCBz, PCPh and PAH in torrefied woody biomass. Fuel, 154, 52-58.
24. Ju, Z. Y ., & Howard, L. R. (2003, July). Effects of solvent and temperature on pressurized liquid extraction of anthocyanins and total phenolics from fried red grape skin. Journal of Agricultural and food chemistry, 51(18), 5207-5213.
25. Connor, K. T., & Aylward, L. L. (2006). Human Response to Dioxin: Aryl Hydrocarbon Receptor (AhR) Molecular Structure, Function, and Dose- Response Data for Enzyme Induction Indicate an Impaired Human AhR.
Journal of Toxicology and Environmental Health, Part B, 147-171.
26.
Allsopp, M., Costner, P., & Johnston, P. (2001). State of knowledge of the impacts of waste incinerator on human health (executive summary).Incineration and Human Health.
22
Appendix A
Isotopically labelled PCDD/Fs congeners in QS, IS and RS Quantification Standard (QS)
PCDFs Content (pg)
2-MoCDF 2000
28-DiCDF 2000
248-TriCDF 2000
2378-TCDF 100
12378-PeCDF 500
23478-PeCDF 500
123478-HxCDF 500
123678-HxCDF 500
234678-HxCDF 450
123789-HxCDF 450
1234678-HpCDF 500
1234789-HpCDF 475
OCDF 1001
PCDDs
2-MoCDD 2000
23-DiCDD 2000
237-TriCDD 2000
2378-TCDD 95
12378-PeCDD 425
123478-HxCDD 500
123678-HxCDD 450
123789-HxCDD 450
1234678-HpCDD 500
OCDD 951
23 Internal Standard (IS)
PCDFs Concentration
(pg/µL) Added volume (µL) Added mass (pg)
2-MoCDF 25 40 1000
28-DiCDF 25 40 1000
248-TriCDF 25 40 1000
2378-TCDF 19,4 40 776
12378-PeCDF 19,4 40 776
23478-PeCDF 19,4 40 776
123478-HxCDF 19,4 40 776
123678-HxCDF 19,4 40 776
234678-HxCDF 19,4 40 775
123789-HxCDF 38,8 40 1552
1234678-HpCDF 19,4 40 776
1234789-HpCDF 21,2 40 848
OCDF 30 40 1200
PCDDs
2-MoCDD 25 40 1000
23-DiCDD 25 40 1000
237-TriCDD 25 40 1000
2378-TCDD 19,4 40 776
12378-PeCDD 19,4 40 776
123478-HxCDD 19,4 40 776
123678-HxCDD 38,8 40 1552
123789-HxCDD 19,4 40 776
1234678-HpCDD 21,2 40 848
OCDD 30 40 1200
Recovery Standard (RS) PCDD/Fs Concentration
(pg/µL) Added volume (µL) Added mass (pg)
1234-TeCDD 250 40 1000
12346-PeCDF 250 40 1000
123469-HxCDF 250 40 1000
1234689-HpCDF 250 40 1000
