Method development and validation of a GC-ECD procedure for PCB 47, 51, 68

Status:

completed 03/2021

Aims:

Polychlorinated biphenyls (PCBs) are a group of 209 related substances (congeners) that differ only in the number and position of their chlorine atoms. PCBs were used in the past mainly in capacitors and jointing compounds. Their use has been banned in Germany since 1989. The occupational exposure limit (OEL) for PCBs in Germany is 3 µg/m³ in the inhalable and vapour fractions, and is calculated from the sum of six indicator PCBs.

Recent findings have shown that during silicone rubber production the use of a chlorinated netting agent may result in the formation of three tetra-chlorinated PCBs that do not normally occur. The existing PCB analysis method is not intended for these three congeners. A suitable method therefore had to be developed for the substances produced in this new way. The method had to satisfy the requirements of the German TRGS 402 Technical Rules for Hazardous Substances. For this purpose, the performance characteristics set out in various standards, such as the minimum measurement range and the expanded uncertainty, must be taken into account.

The aim of the project was to develop a valid and suitable (GC-ECD) method for the PCBs 47, 51 and 68 and to adopt it as a standard method in the German Social Accident Insurance Institutions' MGU measurement system for exposure assessment.

Activities/Methods:

In the first stage of the project, the individual validation steps for the method were set out with reference to the standards EN 13936 or ISO/CD 23861, DIN 32645 and DIN EN 482.

The validation steps for a (GC-ECD) method were then conducted and evaluated. The method's suitability for use in practice was further reviewed by means of real-case samples.

Finally, the results were evaluated, assessed and the method incorporated into the MGU.

Results:

The method was validated under laboratory conditions and found to meet all requirements regarding methods for hazardous substances. Within the measurement range from 0.1 to 1.3 µg/m³, the mean recovery of the three PCBs (47, 51 and 68) is 102 ±6% and the expanded uncertainty of the method lies within the range of 25 to 28%. The atmospheric humidity has no influence on the result of the analysis. Loaded samplers can be stored without loss for up to 14 days after sampling. A breakthrough is assured not to occur up to a PCB concentration of 6 µg/m³. The method was adopted as a standard method within the MGU.

Measurements are to be performed in silicone tube production as soon as the pandemic situation has eased.

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