Environmental Toxicology and Chemistry, zyxwvutsrqponmlk Vol zyxwvutsrqpo 11, zyxwvutsrqponmlk pp. 181-185, 1992 Printed in the USA Pergamon Press plc 0730-7268/92 $5 zyxwv 00 zyxw + .oO Copyright zyxwv 0 1992 SETAC zyxw Short Communication USE AND EFFICIENCY OF ETHYLENE GLYCOL MONOMETHYL ETHER AND MONOETHANOLAMINE TO TRAP VOLATILIZED [7-I4C]NAPHTHALENE AND I4CO2 C.K. ABBOTT,~ D.L. Soremen$* and R.C. SIMS~$ tToxicology Program, and $Department of Civil and Environmental Engineering, Utah State University, Logan, Utah 84322-8200 zyxwvu (Received 22 February 1991; Accepted 13 June 1991) Abstract - Separation of radiolabeled CO, from volatile parent compound(s) or degradation prod- ucts in air from biodegradation microcosms has been done by using solubility in alkaline vs. non- polar solvents or solutions. However, trapping solvents or solutions used to collect radiolabeled C 0 2 may absorb some volatile intermediate products or the volatilized parent compound. Similarly, sol- vents used to trap volatile radiolabeled degradation intermediates or volatile parent compound may absorb some radiolabeled CO,. If this lack of absorption specificity is significant, the clear inter- pretation of radioactivity-counting analyses may be compromised. A procedure designed to separate volatilized [7-14C]naphthalene and I4CO2from the same air stream was evaluated for its efficiency. Ethylene glycol monomethyl ether (EGME) effectively trapped naphthalene (98.6% recovery) but retained approximately 0.8% of the 14C02,whereas monoeth- anolamine (MEA):methanol:scintillation cocktail solution trapped approximately 99.5% of the naph- thalene and virtually 100% of the CO,. Preliminary studies of the efficiency of trapping solutions for parent compounds and mineralized C02 should be made before conclusions are made concern- ing the extent or rate of mineralization based on the amount of radiolabeled carbon retained in a trapping solution. Keywords - Radiolabeled compounds Trapping Biodegradation Mineralization Carbon dioxide IN T R 0 DUCT I0 N and occurrence of radiolabeled carbon in the car- bon dioxide trap have been used by many investi- The use of radiolabeled ComPounds has in- CKased the ease, sensitivity, and accuracy with which measurements can be con- ducted for determining fate and behavior, as well as treatment efficiency, of organic chemicals in lab- oratory soil and water systems. Radiolabeled corn- pound use with alkali or quaternary amine carbon environmental microcosm degradation studies [ 1- lo]. Very low concentrations of radioactive carbon can be measured in each phase (air, aqueous, oil, soil) of an environmental system, and liquid scin- tillation analysis of carbon dioxide trapping soh- tions is quick and easy. from extractable fractions of an environmental sample gators as indications of mineralization [1-5,7-9]. However, in any environmental system, chemicals will be divided among all of the available phases on the basis of solubility, volatility, and sorption dy- namics. c~~~~~~~~~~ made from scintillation count- ing of disintegrations per minute from lone carbon dioxide trapping so~utions may be in error. for separating volatilized parent and intermediate compounds from mineralized coZ. Scheunert et al. [ 111 suggest using a sequence of trapping solu- tions, with an organic chemical trap ahead of an alkali carbon dioxide trap to separate volatilized organic chemicals from evolved carbon dioxide, that is, parent compound and/or intermediates from mineralized product. Heitkamp et zyx [12-141 used volatile organic trapping columns, and Wat- wood et al. [15] used activated carbon that needed to be combusted in order to count the radiolabeled fore determination of the radiolabeled carbon. dioxide trapping solutions has become common in Several investigators have evaluated approaches The disappearance Of parent *To whom correspondence may be addressed. The current address of D.L. Sorensen is Utah State . University, Utah Water Research Laboratory, Logan, UT carbon. Additional handling steps were needed be- 84322-8200. 181