Analysis of PCDD/Fs and dioxin-like PCBs in atmospheric deposition samples from the Flemish measurement network: Optimization and validation of a new CALUX bioassay method

摘要

Since the CALUX (Chemically Activated LUciferase gene expression) bioassay is a fast, sensitive and inexpensive tool for the analysis of a high number of samples, validation of new methods is urgently needed. In this study, a new method for the analysis of PCDD/Fs and dioxin-like PCBs in atmospheric deposition samples with the CALUX bioassay was developed, optimized and validated. The method consists of 4 steps: filtration, extraction, clean up and bioassay analysis. To avoid the use of large amounts of toxic solvents, new techniques were used for filtration and extraction: a C18 filter was used instead of a liquid/ liquid extraction and an Accelerated Solvent Extractor (ASE) was used instead of the traditional soxhlet extraction. After pre-oxidation of the sample extract, clean up was done using a multi-layer silica gel column coupled to a carbon column. The PCDD/F and PCB fractions were finally analyzed with the H1L7.5cl and/or the HlL6.1c3 mouse hepatoma cell lines. The limit of quantification was 1.4 pg CALUX-BEQm~2 d~(-1) for the PCBs and 5.6 pg CALUX-BEQ m~(-2) d~(-1) for the PCDD/Fs, when using the new sensitive HlL7.5cl cell line. The GC-HRMS recovery for all PCDD/F congeners was between 55% and 112%, with a mean recovery of 90%. CALUX recoveries of spiked procedural blanks were between the accepted ranges of 80-120%. Repeatability and reproducibility were satisfactory and no interferences from metals were detected. The first results from the Flemish measurement program showed good correlation between CALUX and GC-HRMS.