Ulrich Servos,1 Dr Franz Kramp2 and Dr Margit Geissler,2
1 Shimadzu Deutschland GmbH, Duisburg, Germany,
2 Shimadzu Europa GmbH, Duisburg, Germany.
Contamination of public buildings with PCBs used as softeners in the 1970's in sealants and wall and ceiling paints can still
be detected. If certain threshold values in indoor air are exceeded the source has to be decontaminated. This requires an
effective and fast determination of the PCB concentration in indoor air. Thermodesorption GC–MS is a method especially suitable
for this purpose. Polychlorinated Biphenyls (PCBs) are highly toxic and carcinogenic chemical substances. Although first prepared
in 1864, they have been industrially manufactured since 1929. The highest production amounts worldwide were recorded in the
1960s and the beginning of the 1970s. In the 1970s their use as additives for building materials was widespread because of
their flame inhibiting and noise reduction properties.
The use of PCBs in open systems was banned in Germany in 1978 after the eco-toxicity of PCBs became known. However, for closed
systems (e.g., transformers) PCBs could still be used in Germany until 1989. The contamination of indoor air by PCBs can lead
to chronic intoxication even with low PCB concentrations, especially if intake occurs over a longer period of time. Acknowledging
this fact, a high level of responsibility concerning public buildings such as kindergardens, schools and administrative buildings
is required.
A concentration of less than 300 ng/m3 of PCB in indoor air can be tolerated in the long-term, and this value is the target of decontamination works.1 For indoor air concentrations between 300 and 3000 ng PCB/m3 air the source of the contamination has to be found and eliminated medium-term. The target should be to achieve a concentration
value of less than 300 ng PCB/m3 . At concentrations above 3000 ng PCB/m3 acute health risks are possible (level for immediate action). Because of their persistence in the environment, their bio accumulation and potential for long range transport as well as
their harmful effects on the environment and health, PCBs belong to the class of persistent organic pollutants (POP). Therefore,
they fall under the Stockholm treaty for the removal of POPs from May 2001 which became effective on 17 May 2004.
Determination of PCBs
The determination of PCBs in indoor air is usually performed by GC–MS. After sampling on polyurethane foam a soxhelt extraction
takes place for several hours.2 An alternative to this procedure is the method of thermodesorption. For sampling, special sample tubes are used, which are
subsequently analysed with an autosampler, the so-called thermodesorber. In the thermodesorber the analytes are desorbed automatically
from the sample tube and transferred to the GC–MS for analysis.
PCB-Analysis Using GC–MS
Figure 1
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PCBs were used in the form of technical mixtures such as Chlophen A30, A40 and A60. These mixtures contain a large number
of single compounds. Overall 209 congeners are possible. Depending on the chlorination degree the PCBs are numbered from 1
to 209, with the perchlorinated Decachlorobiphenyl being PCB 209 (Figure 1). Quantification of a PCB mixture is performed
using certain PCB congeners as representative key compounds for the whole range of PCBs present in the mixture.
