Membrane-enclosed sorptive coating MESCO

A passive sampling device was constructed using the commercially available Twister sorbent stir bar by enclosing it inside a dialysis membrane. This device has been called a membrane-enclosed sorptive coating sampler or MESCO. Extraction efficiencies were three orders of magnitude lower than for SPMD due a lower sampling rate, however, the sensitivity was comparable because all of the collected analyte is desorbed into the GC whereas in SPMD, only a small sample in injected for analysis. Twister stir bars are also much smaller and can be deployed less conspicuously. 

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