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Science 24 October 1997:
Vol. 278. no. 5338, p. 549
DOI: 10.1126/science.278.5338.549l
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Filters are often used to remove particles or molecules completely from solution, but usually they are not used to separate different small molecules in solution, as is done in chromatography. Jirage et al. have chemically plated polymeric membranes with gold to form nanopores with ends capped by even narrower orifices, or "bottlenecks." They show that such membranes can be constructed to filter small molecules on the basis of size. Pyridine (with a molecular weight of 79) passed through such a membrane, but quinine (with a molecular weight of 324) could not be detected in the filtrate.




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