The presence of dichloromethane on cleaned XAD-2 resin: A potential problem and solutions

Preparation of XAD-2 resin for indoor air sampling with commonly used cleaning methods, such as Soxhlet extraction with dichloromethane (DCM) followed by vacuum drying and nitrogen purging, can lead to elevated DCM levels (> 100 ppb) in the sampled indoor air, which result from DCM remaining in the resin after cleaning. Since DCM is a suspect human carcinogen, indoor human exposure to DCM should be minimized. Several procedures to remove residual DCM after Soxhlet extraction were evaluated. Removal by fluidizing the XAD-2 resin bed in a drying column with a nitrogen stream at 40{degree}C was best. The effectiveness of this procedure was demonstrated in parallel air sampling with a syringe sampler and with a prototype quiet sampler equipped with a quartz fiber filter and an XAD-2 cartridge in series. Sampling was conducted in an office and in residence. With the modified procedures, indoor DCM levels were at typical indoor values. (< 10 ppb).