Michael Kraft

Selective determination of 2,3,7,8-tetrachlorodibenzo-p-dioxin in the presence of a large excess of other polychlorinated dibenzodioxins and polychlorinated dibenzofurans

ZusammenfassungEin Verfahren wird beschrieben, das die selektive Abtrennung von 2,3,7,8-TCDD aus einer Mischung von allen PCDDs und PCDFs erlaubt. Dies geschieht durch Fraktionierung an Alumina Woelm B Super I, wodurch eine getrennte Elution aller PCDDs und PCDFs von 2,3,7,8-TCDD erreicht werden kann. Dieses Verfahren erlaubt die quantitative Bestimmung von 2,3,7,8-TCDD mit höherer Nachweisempfindlichkeit in Proben, die andere TCDDs bzw. PCDDs und PCDFs in extremen Überschüssen im Vergleich zu 2,3,7,8-TCDD enthalten. Am Beispiel der Bestimmung von 2,3,7,8-TCDD in Pentachlorphenol und in einem Produktionsrückstand von 2,4-Dichlorphenol wird die praktische Anwendbarkeit nachgewiesen.SummaryA procedure is described for the selective separation of 2,3,7,8-TCDD from all other PCDDs and PCDFs. For this purpose the mixture of PCDDs and PCDFs is fractionated on Alumina Woelm B Super I in such a manner that all PCDDs and PCDFs are eluted prior to 2,3,7,8-TCDD. This procedure allows a more sensitive quantitative determination of 2,3,7,8-TCDD in samples which contain 2,3,7,8-TCDD only as a very minor fraction of the other TCDDs or PCDDs and PCDFs. Determination of 2,3,7,8-TCDD in pentachlorophenol and in a waste sample from 2,4-dichlorophenol production by this procedure is described.

Problems Associated With the Measurement of PCDD and PCDF Emissions From Waste Incineration Plants

Abstract Fly ash and stack gases from municipal waste and industrial incinerators in the F.R.G. have been analyzed for dioxins (PCDD and PCDF). Most of the currently used procedures of stack gas sampling for PCDD/PCDF have been compared and were found to be equally effective. Differences are found, however, in the recovery of surrogates added to the sampling train before sampling, which makes it difficult to validate the sampling procedure. The analysis for PCDD%PCDF in stack gas or fly ash samples from municipal waste incinerators can no longer be considered an analytical problem. Thirty samples of stack gas from a single (old) municipal waste incinerator showed wide variation in PCDD/PCDF emission, indicating that single measurements are not useful in characterizing a plant for average PCDD/PCDF emission. It will be extremely difficult to correlate plant operating conditions to PCDD/PCDF stack gas emissions or PCDD/PCDF fly ash concentrations, because the effects produced by changing conditions are obscured by the variations which occur in PCDD/PCDF concentrations during steady conditions. The variations found under steady conditions can be explained by the proposed mechanisms of PCDD/PCDF formation and decomposition at low temperatures catalyzed by fly ash. Incineration of hospital waste and pyrolytic reclamation of copper in cables and aluminium produced significant emission of PCDD/PCDF. A major noncombustion source of higher chlorinated PCDD/PCDF (tetra- to octa-isomers) is pentachlorophenol, a widespread preservative which contributes to the PCDD/PCDF concentrations found, for example, in sewage sludge, river sediments and house dust.

Parallel Sampling for Dioxins Using Various Sampling Techniques At a Swedish Municipal Solid Waste Incinerator

Abstract Parallel sampling was carried out in a Swedish municipal solid waste (MSW) incinerator, on two consecutive days, with five different sampling techniques. The samples were analysed for chlorinated dioxins (PCDDs) and chiorodibenzofurans (PCDFs) at two laboratories, one in Sweden and the other in Germany. Two different spiking protocols were used, both including pre-sampling or clean-up spikes from each homolog group of the tetra to octa CDDs and CDFs. Comparable results were obtained for all five sampling methods for the emission data and the recoveries for all pre-sampling spikes were above 50%. The agreement between the two laboratories was good. The different sampling methods resulted in very similar congener distributions (congener profiles) or isomer distributions (isomer patterns). However, the sampling techniques differ considerably in the distribution of PCDDs/PCDFs in various sampling compartments. The sampling techniques where large contribution of PCDDs and PCDFs could be found in the wash solvent may suffer from losses and/or cross-contamination problems unless the washing is carried out properly. The use of a cooled probe in combination with an adsorption (polyurethane foam plug) or absorption (ethoxyethanol) trap, where the main portion of the PCDDs and PCDFs were found in the condensate, is considered as a convenient and efficient sampling technique.

PROBLEMS ASSOCIATED WITH THE MEASUREMENT OF PCDD AND PCDF EMISSIONS FROM WASTE INCINERATION PLANTS

Fly ash and stack gases from municipal waste and industrial incinerators in the F.R.G. have been analyzed for dioxins (PCDD and PCDF). Most of the currently used procedures of stack gas sampling for PCDD/PCDF have been compared and were found to be equally effective. Differences are found, however, in the recovery of surrogates added to the sampling train before sampling, which makes it difficult to validate the sampling procedure. The analysis for PCDD/PCDF in stack gas or fly ash samples from municipal waste incinerators can no longer be considered an analytical problem. Thirty samples of stack gas from a single (old) municipal waste incinerator showed wide variation in PCDD/PCDF emission, indicating that single measurements are not useful in characterizing a plant for average PCDD/PCDF emission. It will be extremely difficult to correlate plant operating conditions to PCDD/PCDF stack gas emissions or PCDD/PCDF fly ash concentrations, because the effects produced by changing conditions are obscured by the variations which occur in PCDD/PCDF concentrations during steady conditions. The variations found under steady conditions can be explained by the proposed mechanisms of PCDD/PCDF formation and decomposition at low temperatures catalyzed by fly ash. Incineration of hospital waste and pyrolytic reclamation of copper in cables and aluminium produced significant emission of PCDD/PCDF. A major non-combustion source of higher chlorinated PCDD/PCDF (tetra- to octa-isomers) is pentachlorophenol, a widespread preservative which contributes to the PCDD/PCDF concentrations found, for example, in sewage sludge, river sediments and house dust.