Optimization and validation of the CALUX bioassay for analysis of PCDD/Fs and dioxin-like PCBs in deposition material.

Samenvatting

Alternative methods were investigated for the classical soxhlet extraction and HR-GC-MS quantification of
PCDD/Fs and dioxin-like PCBs in deposition samples. These methods included a solid phase extraction (SPE)
with ENVI C18 disks, followed by automated solvent extraction (ASE) and quantification by the CALUX
bioassay.

Toluene and a mixture of n-hexane/acetone (1:1, v/v) were used as extraction solvent. Optimal conditions for the ASE were set at 1500 psi and 125°C with two extraction cycles (6 minute heating period and 5 or 10 minute static period).

Critical parameters included baking of the glassware, modifying the clean-up procedure and sufficiently diluting samples. In addition, plate design revealed to be of importance, with a proposition of excluding the outer wells for reasons of variability of the results.

Recoveries were on average (82 ± 10)% for the ASE extraction and 83% for the soxhlet extraction, both with
toluene. Higher recoveries of (90 ± 7)% were obtained for the n-hexane/acetone mixture using the ASE. For the extraction with n-hexane/acetone, the limit of detection (LOD) was found to be 1.4 pg TEQ/(day m²) for the PCDD/F fraction and 0.7 pg TEQ/(day m²) in case of the PCB fraction. Limits of quantification (LOQs) ranged from 2.8 to 3.8 pg TEQ/(day m²) for the PCDD/F fraction and from 1.4 to 2.9 pg TEQ/(day m²) for the PCB fraction.

Interferences of heavy metals were small and almost non-existing. In addition, repeatability results were
satisfactory for the PCDD/F fraction (RSD: 6.97%) and PCB (RSD: 6.22%) fraction, as was the reproducibility.

In conclusion, the alternative method allows a faster and more cost effective analysis of deposition samples, ultimately resulting in a higher throughput of samples and additional sampling locations, thereby guaranteeing a better monitoring and risk assessment of PCDD/Fs and PCBs in the environment.

Datum prijs	3 jul 2009
Originele taal	English
Begeleider	Marc Elskens (Promotor), Willy Baeyens (Promotor) & Kim Croes (Advisor)