Liquid lid for biochemical reactions in chip-based nanovials

The present paper describes a new technique to suppress evaporation of solv ent from very small volumes. Vials (15 nl) on a silicon microchip were fill ed with water, and covered with a thin, flowing film of a volatile liquid ( e.g., octane). Water evaporation was greatly reduced. At 37 degrees C, no a ppreciable loss of water could be observed over a period of 90 min. At 95 d egrees C, most of the water sample was left in the vial for more than 3 min . The applicability of the method is demonstrated by a tryptic digest, wher e the resulting peptide fragments were analyzed by capillary electrophoresi s. In addition, a discussion of the possibilities and limitations of some a lternative methods is included in the paper, as well as an outlook on futur e developments of the liquid lid concept. (C) 2000 Elsevier Science B.V. Al l rights reserved.