Analytical Method Development for the Screening and Determination of Dioxins in Clay Matrices

Abstract

Dioxin‐contaminated kaolin receives great attention by workers in the fields of environmental science, soil geology, and mining, due to its impact on the areas of health and business. The concept of “natural dioxin” formation in the clay attracts researchers to look for dioxins quantities in these soils and establish the actual route of their formation, as already proved their presence in large unjustified quantities in a number of kaolinitic soil sources and in a unique profile that denies any anthropogenic sources. On the other hand, other researches revealed the absence of dioxins in other kaolinitic sources. For rapid screening of dioxins presence an analytical method was developed basically for the determination of octachlorodibenzo‐p‐dioxin (the major dioxin congener in dioxin‐contaminated kaolin) and octachlorodibenzofuran (does not exist in dioxin‐contaminated kaolin). The method was considered as a rapid, selective, accurate and sensitive method for screening octachlorodibenzo‐p‐dioxin (OCDD) and octachlorodibenzofuran (OCDF). The method achieved linearity for OCDD/F over the range 126.5–6144.0 ng/kg dry weight (dw) with limit of quantitation of 76 ng/kg dw for OCDD and 111 ng/kg dw for OCDF. The precision (RSD%) ranged between 1.87 and 8.09% for OCDD and between 3.93 and 9.48% for OCDF. Recovery was between 85.5 and 91.1% for OCDD and between 57.9 and 64.1% for OCDF, while the accuracy for OCDD ranged from 93.8 to 97.8% and from 102.9 to 125.1% for OCDF. The developed analytical method in this research is a good alternative for known methods, because it saves time, effort, supplies, and equipments for chemical analysis. It shortens the analysis time to less than a quarter (6 h) and need less chemicals. Also it is suitable for work on a normal resolution GC/MS rather than high resolution one.