Concentrating on the Target

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Science  26 Jan 2001:
Vol. 291, Issue 5504, pp. 555
DOI: 10.1126/science.291.5504.555b

Small neutral molecules (such as drugs or pollutants) are important targets for “labs on a chip.” However, many analytical methods rely on general detection methods such as ultraviolet or visible absorption spectroscopy. For miniaturized systems, low concentrations, small sample volumes, and short path lengths for light can limit sensitivity.

Palmer et al. show that for capillary electrophoresis, sample plug injections (and thus the total amount of analyte) are not limited by the physical length of the capillary. Sample plugs longer than the entire capillary were injected by electroosmotic flow: a co-ion boundary with opposite ion mobility “stacks” (concentrates) the neutral analytes. This injection method is at least as sensitive, and approximately an order of magnitude faster, than previous injection methods, and could be used for a wide variety of neutral analytes with hydrophobic character, such as polycyclic aromatic hydrocarbons, small biomolecules, and environmental contaminants. — PDS

Anal. Chem., in press.

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