Several operating parameters were evaluated to assess the efficiency of an XAD-2 resin column for use in an automated sampling unit to be developed for the analysis of polychlorodibenzo-p-dioxins (PCDDs) in water. Direct standard addition of mass labelled congeners onto the column were used to evaluate the capacity of the resin for PCDDs. Ratios of resin volume and bed volume flow rates were systematically varied. Flow rates of 3 to 24 bed volumes per minute were used without observable breakthrough. Column behaviour was evaluated using the continuous standard addition technique to determine the optimum flow rate for minimal breakthrough, which was found to be 3 bed volume/min. PCDD recoveries were quantitative (75) except for octachlorodibenzodioxin where lower recoveries (approximately 40) were due to losses in the cleanup procedure and not to the sampling. Recoveries of the five congeners used in this study confirm that XAD-2 resin exhibits an extracting capability of organic contaminants from water equal to that of liquid-liquid extraction and allows both a much larger sample size and easier sampling.
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