Optimization of the purification method for dioxin analysis in human serum and temporal changes in background dioxin levels in the general population

To perform high quality and high throughput measurements, complicated purification procedure by two rounds of open column chromatography was simplified by appraising the components and adding a sufficient amount of adsorbents to the column. The procedure consists of two open column techniques using a multi-layer silica gel column and an active carbon dispersed silica gel column. This purification procedure is used in “Standard manual for dioxin analysis in human blood” published in 2000 (Ministry of Health and Welfare, Japan, 2000). Consequently, a purification procedure using only 1 g of 10% AgNO3/silica gel can remove the matrix of blood serum as effectively as a multi-layer silica gel column. In addition, 0.1 g of carbon silica gel, equivalent to 1/10 the weight used currently in analyses, separates and recovers the dioxins in purified extract of blood serum. Furthermore, changes in the background level in the general population were clarified by monitoring the dioxin concentrations in human blood. The dioxin concentrations and ratios in blood in the general population remained at a tolerable level for three months. Therefore, the blood serum was available for the detection of a remarkable elevation in dioxins level considered to be indicative of contamination due to high-density exposure.