Fly ash extract

Opperhuizen, A., Wagenaar, W.J., Van der Wielen, F.W.M., Van den Berg, M., Olie, K., O. Hutzinger, O., Gobas, F.A.P.C. (1986) Uptake and elimination of PCDD/PCDF congeners by fish after aqueous exposure to a fly ash extract from a municipal incinerator. Chemosphere 15, 2049-2053. 

A method for determining CDDs in municipal incinerator fly ash has been reported (Alexandrou and Pawliszyn 1990). The method uses supercritical fluid extraction (SFE) to recover CDDs from fly ash samples prior to GC. Supercritical fluid extraction is faster and less expensive than the typically used Soxhlet extraction and gives quantitative removal of CDDs and CDFs from fly ash. Extracts obtained using SFE will still require additional clean-up steps prior to analysis. Supercritical C02 has also been used to assist solvent-based extraction of CDDs from soils (Friedrich and Kleibohmer 1997). In this case, the supercritical fluid was combined with accelerated solvent extraction (liquid extractions conducted under elevated temperature and pressure) to provide good recoveries relative to Soxhlet extractions. 

Van den Berg M, Meerman L, Olie K, et al. 1986a. Retention of PCDDs and PCDFs in the liver of the rat and hamster after oral administration of a municipal incinerator fly ash extract. Toxicol Environ Chem 12 267-284. 

Van den Berg M, Olie K, Hutzinger 0. 1983. Uptake and selection in rats of orally administered chlorinated dioxins and dibenzofurans from fly-ash and fly-ash extract. Chemosphere 12 537-544. 

Morita M, Ito H, Yasuhara A, Moriyama H, Asada S (1994), Organohalogen Compounds 19 261-264. Fly-ash extract - A proposed reference material for PCDDs, and PCDFs11 Eds. University of Kyoto, Japan... 

In cases where methods are similar or show common steps, it is essential to examine if no systematic bias is affecting the results. In some few cases, BCR was confronted with situations where participants had to use a common calibration material (certification of dioxins and furans in a fly ash extract). Such a situation offers the possibility of introducing a systematic error into the study and consequently of a bias of the certified value. Situations where suppliers cannot propose reliable calibration substances may oblige the certification body to provide a common material. It should remain an exception and if unavoidable, the producer of the common calibrant should follow a strict preparation procedure similar to the one described above for the certification of calibrants. 

In the last twenty years, PCDD and PCDF were identified as by-products in many industrial processes which involve chlorine or chlorinated compounds. Additionally both groups of compounds were found to be formed in a broad range of combustion processes, including accidental fires. Municipal waste incineration is particularly considered to be a very important, if not the most important, of the identified source of environmental dibenzo-p-dioxin and dibenzofuran contamination. As a consequence, the evaluation and close control of new and existing installations for their dioxin releases has become a major concern. Based on this relative importance of municipal waste incinerators, and taking into account the relative toxicity data actually available for PCDD and PCDF, it was decided to prepare and certify a crude fly ash extract (CRM 429) for the twelve more toxic PCDD and PCDF [18,19]. 

The stability was verified over 12 months of storage in a refrigerator between 0 and 4°C and by comparing the results with those obtained on samples of the freshly prepared fly ash extract (12 months before). No instability could be demonstrated for any of the monitored compounds. 

The selective determination of F94 (1,2,3,7,8-P5CDF) in the fly ash extract cannot be performed on a common polar capillary column such as CP Sil 88 or SP 2331. The results obtained on these columns were not acceptable for certification. Instead a special polar column, coded DB Dioxin, performs well, as do almost all of the commonly used non-polar capillary columns (CP Sil 5 CB, DB 5, HP 5 etc.). 

The certified PCDD and PCDF contents in the fly ash extract are given in Table 11.8, along with their uncertainties. Recommendations on the analysis of the CRM 429 are given in the certification report [19] and published elsewhere [18]. 

Fig. 12.2. Values for mass fractions of FI 18 in a fly ash extract reference material, expressed in pg kg. Results obtained by Lab. 05 correspond to the use of a DB Dioxin column, which allows a better resolution for FI 18/Fl 19.

---