Evaluation of Column Cleanup for Chlorobenzenes, Polychlorinated Biphenyls, Polychlorinated Dibenzo-p-dioxins, and Polychlorinated Dibenzofurans in MM5 Flue Gas Analysis

Abstract

The recoveries of chlorobenzenes (CBs), polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) from the acid-base-on-silica column (ABS), the silver nitrate-on-silica column (SNS), and the alumina column (ALM) were investigated using eluents with various concentrations of dichloromethane in hexane. PCBs recoveries from the ABS and ALM columns are generally increased with increasing number of chloro substituents. However, PCBs recoveries are also complicated by the inductive and resonance contributions due to the different conformation and electron density of the congeners. The recoveries of PCBs with lower number of chloro substituents decreased with increasing silver nitrate content coated on silica. With 2% dichloromethane in hexane (as normally used in MM5 analysis), the recoveries of all CBs and trichloro- to decachlorobiphenyls from ABS, 10% SNS, and ALM columns in series are ≥80%. However, the 2,4-dichlorobiphenyl is only 16% recovered, and monochlorobiphenyls are not recovered at all. Under these conditions, the recoveries of PCDDs/PCDFs from ABS and 10% SNS columns in series are ≥80%. With 60% dichloromethane in hexane, PCDDs/PCDFs recoveries from ALM column are ≥80%. The implication of the selective adsorption of PCBs on the fractionation of CBs/PCBs and PCDDs/PCDFs from these MM5 cleanup columns is discussed.

Time-Resolved Laser-Excited Phosphorimetry at Liquid Helium Temperature for the Direct Analysis of 2,3,7,8-Tetrachloro-Dibenzo-Para-Dioxin in Complex Mixtures

“…Substantial research concerning the environm ental analysis of polychlorinated dibenzo-p-dioxins (PCDD) has been published in the past 20 years. [1][2][3][4][5][6][7][8][9][10][11] This interest is due to the toxic, mutagenic, and carcinogenic properties that all these compounds possess to some degree. Because of halogenation, PCDD are in general lipophilic, stable, and resistant to enzymatic conversion to watersoluble derivatives.…”

“…Of these, only those dioxins with four chlorines or more are considered environmentally relevant; PCDD with fewer than four chlorines do not bio-accumulate. Among them, 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8 CDD) is known to show the highest toxicity to m an and by de nition has a toxicity equivalency (TEQ) of one. All the remaining PCDD isomers have a TEQ lower than one.…”

Method for Multiresidue Determination of Halogenated Aromatics and PAHs in Combustion-Related Samples

“…The current European (26) and American (27) approved standard methods for PCDD/F cleanup and GC/MS determination share many features. Method evaluations have shown the cleanup procedures to be valid for several groups of compounds (26,(28)(29)(30)(31). Due to their laborious nature, not least for their development and validation, they have changed relatively little over the years.…”