Mass Spectrometry
in the analysis
of Persistent Organic Pollutants
Anton Kočan, Jana Klánová

Tools for determining chemical structure
•IR
•UV-VIS
•X-ray crystallography
•NMR
•Mass spectrometry (MS)
Kurt Wuthrich a John B. Fenn (1/4) + Koichi Tanaka (1/4) shared the Nobel Price in chemistry for
2002.
The latter two for the development of soft desorption ionization methods for mass spectrometric
analyses of biological macromolecules
Altogether, 5 scientists have been awarded the Nobel Price in connection with mass spectrometry –
Joseph Thompson in 1906, Francis Aston in 1922, Wolfgang Paul in 1989, and J. Fenn and K. Tanaka in
2002
A. Kočan, Slovak Medical University

Advantages of Mass Spectrometry
•Mixtures can be analyzed
•A small amount of substance is sufficient
Disadvantages of Mass Spectrometry
•The evaluation of mass spectra is demanding
•It is a destructive method
A. Kočan, Slovak Medical University

Ion
Source
Mass
Analyzer
Ion
Detector
Vacuum
Pumps
Inlet
Sample
Introduction
Data
System
Data
Output
Mass Spectrometer
•All the MS systems compose of the following parts:
Ionization, separation of ions
and their detection
take place in vacuum
(~ 10-4 – 10-6 Pa)
•Electron multiplier
•Photomultiplier
•Microchannel plate
•Magnetic-sector
•Quadrupole
•Ion trap
•Time-of-flight
•Ion-cyclotron resonance
•Electron impact (EI)
•Chemical ionization (CI)
•Electrospray (ESI)
•Fast-atom bombardment (FAB)
•Laser ionization (LIMS)
•Resonance ionization (RIMS)
•ˇThermal ionization (TIMS)
•Plasma-desorption ionization (PD)
•Matrix-assisted laser desorption ionization (MALDI)
•GC
•LC
•Direct inlet
A. Kočan, Slovak Medical University

Sample Introduction
•Direct inlet to the ion source
–Introduction of the gaseous sample
–Introduction of the liquid or solid sample after their vaporization
•Outlet from the chromatographic column
–Gas chromatography – packed column (a carrier gas separator is needed)
  – capillary column (directly to the ion source)
–Liquid chromatography (the separation of the mobile phase is essential)
HexaCDFs
separated by
packed column
3% Dexsil 300
on Supelcoport
100/120
2.4 m, 2 mm i.d.
capillary
column
SP-2331
60 m
0.25 mm i.d.
0.2 mm
A. Kočan, Slovak Medical University

Electron Impact Ionization Source
~70 Volts
+
_
+
_
e-
e-
e-
+
+
+
+
+
+
_
Electron Collector (Trap)
Repeller
Extraction
Plate
Filament
to
Analyzer
Inlet
Electrons
Neutral
Molecules
Positive
Ions
The molecules are bombarded by electrons (e-) emitted by a heated filament (W or Re) in vacuum (~
10-5 – 10-6 mbar)
A. Kočan, Slovak Medical University

Electron Impact Ionization Source
~70 Volts
+
_
+
_
e-
e-
e-
+
+
+
+
+
+
_
Electron Collector (Trap)
Repeller
Extraction
Plate
Filament
to
Analyzer
Inlet
Electrons
Neutral
Molecules
Positive
Ions
The electrons are accelerated towards an anode (electron trap)
A. Kočan, Slovak Medical University

Electron Impact Ionization Source
~70 Volts
+
_
+
_
e-
e-
e-
+
+
+
+
+
+
_
Electron Collector (Trap)
Repeller
Extraction
Plate
Filament
to
Analyzer
Inlet
Electrons
Neutral
Molecules
Positive
Ions
Energy of e- : 15 to 100 eV;
70 eV is usually used for scaning mass spectra
A. Kočan, Slovak Medical University

Electron Impact Ionization Source
~70 Volts
+
_
+
_
e-
e-
e-
+
+
+
+
+
+
_
Electron Collector (Trap)
Repeller
Extraction
Plate
Filament
to
Analyzer
Inlet
Electrons
Neutral
Molecules
Positive
Ions
On their path they collide with gaseous molecules injected into the ion source or eluted from a
GC/LC column
On average, one ion is produced for 1000 molecules entering the ion source at 70 eV
A. Kočan, Slovak Medical University

Electron Impact Ionization Source
~70 Volts
+
_
+
_
e-
e-
e-
+
+
+
+
+
+
_
Electron Collector (Trap)
Repeller
Extraction
Plate
Filament
to
Analyzer
Inlet
Electrons
Neutral
Molecules
Positive
Ions
10 to 20 eV out of those 70 eV are transferred to the molecules during the ionization process;
Since ~ 10 eV are enough to ionize most organic molecules the excess energy leads to extensive
fragmentation;
Hence EI is classified as a „hard“ ionization technique
The fragmentation gives structural information
A. Kočan, Slovak Medical University

Electron Ionization
•One of the oldest and simplest methods (1930 – 1950)
•Applicable for vaporizable samples only, e.g. compounds with low molecular weight (< 1000 Da),
less polar organic molecules
•Advantages:
–Unimolecular fragmentation (ions spend 1 ms in EI source)
–Reproducible technique
•Disadvantages:
–Sometimes M+. is not observed due to fragmentation
–Almost impossible distinguish between isomers (GC separation needed)
–Some compounds can undergo thermal decomposition before ionization because of high temperatures
used to vaporize the sample
–Inappropriate to too involatile compounds
A. Kočan, Slovak Medical University

Schematic of Electron Ionization
Ion-sourceMAT
Ionization
chamber
A. Kočan, Slovak Medical University

Positive Chemical Ionization
•Developed in the 1960s.
•Gaseous ions such as CH5+, C2H5+, C4H9+, NH4+, H3+ generated by electron impact from a large
excess of a reagent gas, such as CH4, NH3, H2, or i-C4H10, interact with neutral molecules that may
ionize.
•Generally, the amount of fragments is much less than in EI since little internal energy is
imparted on the ionized molecule; Thus, the important molecular ion can be determined.
•Hence, CI is termed as „soft“ ionization technique.
A. Kočan, Slovak Medical University

Electrospray



MALDI



ion trajectory
not in register
(too heavy)
Ion
Source
Detector
ion trajectory
not in register
(too light)
ion trajectory
in register
S
N
Electromagnet
Magnetic Sector Mass Analyzer
HPIM3647
A. Kočan, Slovak Medical University

High Resolutionn MS Autospec-Ultima
•3-sector instrument (2 electrostatic sectors, 1 magnetic sector)
VGAutospecMdiagram
•Mattauch-Herzog geometry
VGAutospecMphoto1
A. Kočan, Slovak Medical University

P1220003
Dual HRGC / HRMS System
DB5-ms
Rtx-2330
A. Kočan, Slovak Medical University

Detector
Ion
Source
+
_
_
DC and AC
Voltages
resonant ion
non-resonant ion
+
Quadrupole Mass Filter
quad1
•Consists of 4 parallel metal rods.
•Two opposite rods have an applied potential combined from DC and AC voltages.
•A mass spectrum is obtained by monitoring the ions passing through the quadrupole filter as the
voltages or frequency on the rods are varied.
•For given dc and ac voltages, only ions of a certain mass-to-charge ratio pass through the filter
and all other ions are thrown out of their original path.
•The voltages affect the trajectory of ions traveling down the flight path centered between the
rods.
A. Kočan, Slovak Medical University

TOF MS schematic
Time-Of-Flight Mass Spectrometry (TOFMS)
•It uses differences in transit time through a drift region to separate ions of different masses
•It operates in a pulsed mode so ions must be produced or extracted in pulses
•An electric field accelerates all ions into a field-free drift region with the same initial
kinetic energy for all the ions produced
•Since the ion kinetic energy is 0.5mv2, lighter ions have a higher velocity than heavier ions and
reach the detector sooner (e.g., ions of m/z 500 arrive in ~ 15 ms and m/z 50 in ~ 4.6 ms
Schematic of gas analysis system Photo of TOF-MS for gases
•By TOF-MS, up to 50 000 full spectra can be measured in a second
•Since full spectra are available, peak deconvolution software enabling to differentiate
non-separated GC peaks may be applied
•The TOF ultra-fast scanning is suitable for fast GC where peak widths can be much less then a
second
A. Kočan, Slovak Medical University

Ion Trap Mass Spectrometry
•The advantages of the ion-trap mass spectrometer include compact size, and the ability to trap and
accumulate ions to increase the signal-to-noise ratio of a measurement.
picture of w. paul
Wolfgang Paul
1989 Nobel Price for Physics „for the development of the ion trap technique“
•This technique can be used easily in the MS/MS (MSn) mode
•The ion-trap analyzer consists of 3 electrodes with hyperbolic surfaces to trap ions in a small
volume – the central ring electrode and 2 adjacent endcap electrodes. A mass spectrum is obtained
by changing the electrode voltages to eject the ions from the trap.
A. Kočan, Slovak Medical University

To Amplifier
-3 kV
0 V
Dynode
Electron Multiplier
Continuous-dynode electron multiplier
Discrete-dynode electron multiplier
typical current gain is 106
A. Kočan, Slovak Medical University

fil-hp
§Mean free path of molecules
Why needed?
Vacuum System
üRough pumps
diffusion-180
üDiffusion pumps
üTurbomolecular pumps
§Ion-molecular reactions
§Interferences in mass spectra
§Glowing/sparking in the high-voltage area
§Contamination of the ion source
§Burning of the filament
HPIM3646 HPIM3650
A. Kočan, Slovak Medical University

Mass Spectrum
m/z
(mass-to-charge ratio)
Relative abundance (%)
100
Molecular ion
M+.
Base peak
[M-X]+.
Fragment ion
[M-Y]+.
There are now Internet-accessible databases containing mass spectra of thousands of compounds,
e.g.:
http://www.aist.go.jp/RIODB/SDBS/menu-e.html
http://webbook.nist.gov
A. Kočan, Slovak Medical University

Segment of the Real Signal (not computer-processed) of a Mass Spectrum
(n-cethyl amine – C16H33NH2)
m/z
•Such a Gauss-shaped peaks are processed by a computer program to be converted to the line spectrum
142
156
170
184
198
212
226
241
m/z
A. Kočan, Slovak Medical University

GC-MS Uses
•Identification and quantification of volatile and semivolatile organic compounds in complex
mixtures
•Determination of molecular weights and (sometimes) elemental composition of unknown organic
compounds in complex mixtures
•Structural determination of unknown organic compounds in complex mixtures both by matching their
mass spectra with reference spectra and by a priori spectral interpretation
When to Use HRMS ?
•For the determination of the exact masses of ions in spectra (peak matching) – suitable for the
determination of elemental composition
•Decreasing interferences caused by the ions of co-extracted compounds or by GC column bleeding and
thus, to improve considerably the signal-to-noise ratio
A. Kočan, Slovak Medical University

Fragmentacia_PCDFs Fragmentacia_PCDDs
Fragmentation schemes
under EI conditions
Polychlorinated dibenzo-p-dioxins
Polychlorinated dibenzofurans
* fragmentation for lower chlorinated
    congeners
A. Kočan, Slovak Medical University

Demonstration of Mass Spectrometric Resolution (10% Valley Definition)
R10% = m / Dm
A. Kočan, Slovak Medical University

•In general, more ions have the same nominal mass
•To distinguish between them certain MS resolution is needed
•For example, to separate these 2 ions we need a resolution of 5 124
R = (122.060585 – 122.036776) / 122 = 5 124
A. Kočan, Slovak Medical University

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Relative Abundances of the Combinations of Halogen Isotopes
•Fluorine and iodine are monoisotopic
•However, chlorine is present in the nature as 35Cl (75.8%) and 37Cl (24.2%), and bromine as 79Br
(50.5%) and 81Br (49.5%)
•Therefore molecular ions (or fragment ions) containing various numbers of Cl and/or Br atoms give
rise to typical patterns spaced 2 amu apart based on a combination of (a+b)n; for Cl a is 75.8%, b
24.2% and n is the number of chlorine substituents in a molecule
A. Kočan, Slovak Medical University

M+.
[M+2]+.
[M+4]+.
[M+6]+.
320
[M-Cl]+.
[M-COCl]+.
Upper Segment of 2378-TCDD Mass Spectrum
A cluster created by four Cl-substituents
4×35Cl
3×35Cl
1×37Cl
2×35Cl
2×37Cl
1×35Cl
3×37Cl
4×37Cl
A. Kočan, Slovak Medical University

What is the SCAN Mode in Mass Spectrometry ?
•The scanning mode provides mass spectra. They are recorded (scanned) at regular intervals
(typically 0.5 – 1 /s; much faster if TOFMS is used) during the GC separation and stored in the
instrument data system for subsequent qualitative or quantitative evaluation.
•From mass spectra, it is often possible to deduce structural features (mass spectral
interpretation) but this requires experience and can be very time-consuming, particularly as a
complex mixture might contain hundreds of components.
•The spectra can also be compared with those stored in mass spectral libraries. Although library
searching is a very useful and timesaving technique, it is important to remember that such searches
do not identify compounds – analysts do!
A. Kočan, Slovak Medical University

What is the SIM (or MID) Mode in Mass Spectrometry ?
•SIM (Selected Ion Monitoring) or MID (Multiple Ion Detection) is much more sensitive technique
suitable for trace quantitative analysis. Here, instead of scanning a whole spectrum, only a few
ions (generally, the most abundant but characteristic selected from the mass spectrum) are detected
during the GC run.
•This can result in as much as a 500-fold increase in sensitivity, at the expense of selectivity.
Depending on the analyte, low picogram to even low femtogram amounts can be measured using this
powerful technique.
•Stable isotope-labeled internal standards can be employed.
f3
HRMS/LRMS-SIM chromatogram from the analysis of 2378-TCDD in a soil extract by the isotope dilution
method
2,3,7,8-TCDD
13C12-2,3,7,8-TCDD
M+.
A=1392 (82%)
m/z 319.9
m/z 321.9
m/z 323.9
[M+2]+.
A=1688 (100 %)
[M+4]+.
A=829 (49%)
M+.
A=1936 (80%)
m/z 331.9
m/z 333.9
m/z 335.9
[M+2]+.
A=2415 (100%)
[M+4]+.
A=1198 (50%)
A. Kočan, Slovak Medical University

The Use of the Isotope Dilution HRGC/HRMS in the SIM Mode
13C-labeled
standards
13C-labeled
standards
M+.
M+.
[M+2]+.
[M+2]+.
TetraCDDs
A. Kočan, Slovak Medical University

PeCDF_flyash
A. Kočan, Slovak Medical University


Dioxins and Related Compounds Analysis (1)
Types of samples:
§Emissions from combustion processes (stack aerosol, flyash)
§Wastes (obsolete chemicals, disposal sites)
§Environmental samples (air, soil, water sediment, biota)
§Foods (meat, fish, milk, eggs, oils)
§Human biological material (milk, blood, adipose tissue)
A. Kočan, Slovak Medical University

Sampling
train
Rinsing of sampling
device
Extraction
Concentration
Silica
Silica
+
H2SO4
Silica
Silica
+
NaOH
Silica
Silica
+
AgNO3
Sampling
standards
Extraction
standards
Basic
Alumina
Super I
column
Active
carbon
column
Concentration
GC/MS
Syringe
standards
Flow chart of a clean-up procedure for stack emission samples
A. Kočan, Slovak Medical University

Stack1
Dioxins and Related Compounds Analysis (2)
Sampling:
§The collection of samples should represent the situation, process or the species studied
§Attention must be paid to the appropriate timing of collections of samples, their frequency and
site layout
§Sampling media, particularly those for air and emission sampling should be spiked before sampling
with selected isotope labeled surrogates (13C-sampling standards) to make corrections of losses of
analytes during the sampling
A. Kočan, Slovak Medical University

Dioxins and Related Compounds Analysis (3)
Sampling extraction & cleanup:
§Addition of isotope labeled standards (13C) before extraction
§Solvent extraction (Soxhlet, ASE, ultrasonic, SPE, SFE, MASE)
§Removal of matrix substances (lipids, oils, etc.) – H2SO4, GPC, SPM dialysis
§Removal of interfering coextracted compounds (PCBs, PCDPEs, etc.) – acid/base modified silica,
alumina, active carbon, semi-preparative HPLC)
§Concentration of the analytes
SPE of blood serum
Cleanup on silica/H2SO4 columns
A. Kočan, Slovak Medical University

Schematic of a semi-automatic equipment for sample cleanup
Semi-automated clean-up equipment
A. Kočan, Slovak Medical University

Dioxins and Related Compounds Analysis (4)
GC separation:
§Non-polar stationary phase (e.g. DB-5) – used for the samples of animal origin and higher
chlorinated congeners
§Polar phase (e.g. SP-2330) – used for environmental samples (good separation but shorter lifetime)
§Splitless, on-column or large-volume injection
§Direct connection of the column to the ion source
out of splitless injector
to mass spectrometer
A. Kočan, Slovak Medical University

HxCDF_flyash
Identification Criteria
(according to
the EN 1948 Standard)
§The isotope ratio between the ions monitored shall match the theoretical value within ± 20 %
§The retention time of a native 2,3,7,8-isomer shall be within a time window of (0s;+3s) based on
the retention time of the corresponding 13C12-labelled isomer in the sample. For hepta- and
octachloro-congeners deviations of (-2s;+3s) are acceptable
§The GC column shall separate 2,3,7,8-congeners from interfering congeners with a 90 % valley
relative to the highest peak. 2,3,7,8-TCDF shall be separated from all other interfering isomers
within a 25 % valley
Dioxins and Related Compounds Analysis (5)
M+2
M+4
A. Kočan, Slovak Medical University

Group
Ion
% Abundance
Natives
13C12-labelled
TetraCDFs
TetraCDDs
[M]+.
[M+2]+.
[M]+.
[M+2]+.
77.55
100
77.55
100
303.9016
305.8987
319.8965
321.8935
315.9418
317.9390
331.9398
333.9338
PentaCDFs
PentaCDDs
[M+2]+.
[M+4]+.
[M+2]+.
[M+4]+.
100
64.15
100
64.15
339.8597
341.8567
355.8546
357.8516
351.9000
353.8970
367.8948
369.8918
HexaCDFs
HexaCDDs
[M+2]+.
[M+4]+.
[M+2]+.
[M+4]+.
100
80.54
100
80.54
373.8208
375.8178
389.8156
391.8126
385.8610
387.8581
401.8558
403.8528
HeptaCDFs
HeptaCDDs
[M+2]+.
[M+4]+.
[M+2]+.
[M+4]+.
100
96.52
100
96.52
407.7818
409.7789
423.7766
425.7737
419.8220
421.8192
435.8169
437.8140
OctaCDF
OctaCDD
[M+2]+.
[M+4]+.
[M+2]+.
[M+4]+.
88.89
100
88.89
100
441.7428
443.7398
457.7377
459.7348
453.7830
455.7801
469.7779
471.7750
Mass of ions monitored for tetra- to octaCDDs/Fs when HRMS is applied

Group
Ion
% Abundance
Natives
13C12-labelled
TetraCDFs
TetraCDDs
[M]+.
[M+2]+.
[M]+.
[M+2]+.
77.55
100
77.55
100
303.9016
305.8987
319.8965
321.8935
315.9418
317.9390
331.9398
333.9338
PentaCDFs
PentaCDDs
[M+2]+.
[M+4]+.
[M+2]+.
[M+4]+.
100
64.15
100
64.15
339.8597
341.8567
355.8546
357.8516
351.9000
353.8970
367.8948
369.8918
HexaCDFs
HexaCDDs
[M+2]+.
[M+4]+.
[M+2]+.
[M+4]+.
100
80.54
100
80.54
373.8208
375.8178
389.8156
391.8126
385.8610
387.8581
401.8558
403.8528
HeptaCDFs
HeptaCDDs
[M+2]+.
[M+4]+.
[M+2]+.
[M+4]+.
100
96.52
100
96.52
407.7818
409.7789
423.7766
425.7737
419.8220
421.8192
435.8169
437.8140
OctaCDF
OctaCDD
[M+2]+.
[M+4]+.
[M+2]+.
[M+4]+.
88.89
100
88.89
100
441.7428
443.7398
457.7377
459.7348
453.7830
455.7801
469.7779
471.7750
Mass of ions monitored for tetra- to octaCDDs/Fs when HRMS is applied

Group
Ion
% Abundance
Natives
13C12-labelled
TetraCDFs
TetraCDDs
[M]+.
[M+2]+.
[M]+.
[M+2]+.
77.55
100
77.55
100
303.9016
305.8987
319.8965
321.8935
315.9418
317.9390
331.9398
333.9338
PentaCDFs
PentaCDDs
[M+2]+.
[M+4]+.
[M+2]+.
[M+4]+.
100
64.15
100
64.15
339.8597
341.8567
355.8546
357.8516
351.9000
353.8970
367.8948
369.8918
HexaCDFs
HexaCDDs
[M+2]+.
[M+4]+.
[M+2]+.
[M+4]+.
100
80.54
100
80.54
373.8208
375.8178
389.8156
391.8126
385.8610
387.8581
401.8558
403.8528
HeptaCDFs
HeptaCDDs
[M+2]+.
[M+4]+.
[M+2]+.
[M+4]+.
100
96.52
100
96.52
407.7818
409.7789
423.7766
425.7737
419.8220
421.8192
435.8169
437.8140
OctaCDF
OctaCDD
[M+2]+.
[M+4]+.
[M+2]+.
[M+4]+.
88.89
100
88.89
100
441.7428
443.7398
457.7377
459.7348
453.7830
455.7801
469.7779
471.7750
Mass of ions monitored for tetra- to octaCDDs/Fs when HRMS is applied

Group
Ion
% Abundance
Natives
13C12-labelled
TetraCDFs
TetraCDDs
[M]+.
[M+2]+.
[M]+.
[M+2]+.
77.55
100
77.55
100
303.9016
305.8987
319.8965
321.8935
315.9418
317.9390
331.9398
333.9338
PentaCDFs
PentaCDDs
[M+2]+.
[M+4]+.
[M+2]+.
[M+4]+.
100
64.15
100
64.15
339.8597
341.8567
355.8546
357.8516
351.9000
353.8970
367.8948
369.8918
HexaCDFs
HexaCDDs
[M+2]+.
[M+4]+.
[M+2]+.
[M+4]+.
100
80.54
100
80.54
373.8208
375.8178
389.8156
391.8126
385.8610
387.8581
401.8558
403.8528
HeptaCDFs
HeptaCDDs
[M+2]+.
[M+4]+.
[M+2]+.
[M+4]+.
100
96.52
100
96.52
407.7818
409.7789
423.7766
425.7737
419.8220
421.8192
435.8169
437.8140
OctaCDF
OctaCDD
[M+2]+.
[M+4]+.
[M+2]+.
[M+4]+.
88.89
100
88.89
100
441.7428
443.7398
457.7377
459.7348
453.7830
455.7801
469.7779
471.7750
Mass of ions monitored for tetra- to octaCDDs/Fs when HRMS is applied

Group
Ion
% Abundance
Natives
13C12-labelled
TetraCDFs
TetraCDDs
[M]+.
[M+2]+.
[M]+.
[M+2]+.
77.55
100
77.55
100
303.9016
305.8987
319.8965
321.8935
315.9418
317.9390
331.9398
333.9338
PentaCDFs
PentaCDDs
[M+2]+.
[M+4]+.
[M+2]+.
[M+4]+.
100
64.15
100
64.15
339.8597
341.8567
355.8546
357.8516
351.9000
353.8970
367.8948
369.8918
HexaCDFs
HexaCDDs
[M+2]+.
[M+4]+.
[M+2]+.
[M+4]+.
100
80.54
100
80.54
373.8208
375.8178
389.8156
391.8126
385.8610
387.8581
401.8558
403.8528
HeptaCDFs
HeptaCDDs
[M+2]+.
[M+4]+.
[M+2]+.
[M+4]+.
100
96.52
100
96.52
407.7818
409.7789
423.7766
425.7737
419.8220
421.8192
435.8169
437.8140
OctaCDF
OctaCDD
[M+2]+.
[M+4]+.
[M+2]+.
[M+4]+.
88.89
100
88.89
100
441.7428
443.7398
457.7377
459.7348
453.7830
455.7801
469.7779
471.7750
Mass of ions monitored for tetra- to octaCDDs/Fs when HRMS is applied

Quantification criteria
(according to the EN 1948 Standard)
§The S/N ratio of the raw data shall be at least 3:1 for the signal used for quantification
§The calibration is carried out with at least 5 calibration solutions
§The measuring range shall be linear
§Daily calibration checks shall be run
§HRMS at 6000 to 10000 resolution can be used if the absence of interferences is documented
§Other techniques can be used if show meeting the criteria
Dioxins and Related Compounds Analysis (6)
A. Kočan, Slovak Medical University

•This conversion is based on the assumption that all the 2,3,7,8-substituted PCDDs and PCDFs (17
cong.), as well as the dioxin-like PCBs (12 cong.), bind to the same receptor, the Ah receptor, and
show comparable qualitative (toxic) effects, but with different potencies
TEQ = (PCDDi × TEFi) + (PCDFi × TEFi ) + (PCBi × TEFi )
Conversion of Analytical Results
into the Toxic Equivalent (TEQ)
•These differences in toxicity are expressed in the toxic equivalency factors (TEFs)
•TEF of the most toxic 2378-TCDD = 1
Congener
I-TEF
WHO-TEF
Congener
I-TEF
WHO-TEF
2378-TCDD
1
1
2378-TCDF
0.1
0.1
12378-PeCDD
0.5
1
23478-PeCDF
0.5
0.5
123478-HxCDD
0.1
0.1
12378-PeCDF
0.05
0.05
123678-HxCDD
0.1
0.1
123478-HxCDF
0.1
0.1
123789-HxCDD
0.1
0.1
123789-HxCDF
0.1
0.1
1234678-HpCDD
0.01
0.01
123678-HxCDF
0.1
0.1
OCDD
0.001
0.0001
234678-HxCDF
0.1
0.1

1234678-HpCDF
0.01
0.01

1234789-HpCDF
0.01
0.01

OCDF
0.001
0.0001
A. Kočan, Slovak Medical University

Relative Response
Factors
Quantification
Ci = Qi,12C / Vnr
CT = S (Ci × I-TEFi )
Extraction Standards
Recovery
Sampling Standards
Recovery
Calculations Regarding Dioxin Determination
by the Isotope Dilution Method
A. Kočan, Slovak Medical University