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Droplet size control with methanol‐repellent surface in a sampling device for continuous annular electrochromatography
Author(s) -
Wang Qi,
Rebrov Evgeny V.,
Hessel Volker
Publication year - 2012
Publication title -
journal of separation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.72
H-Index - 102
eISSN - 1615-9314
pISSN - 1615-9306
DOI - 10.1002/jssc.201100622
Subject(s) - capillary action , electrolyte , methanol , chemistry , chromatography , analytical chemistry (journal) , materials science , capillary electrochromatography , chemical engineering , composite material , electrode , organic chemistry , engineering
The eluent droplet size defines the number of sampling compartments in a continuously operated annular electrochromatograph and therefore influences separation efficiency. In this work, an assembly of two capillaries, a feeding capillary on the top and a receiving capillary placed under it, has been investigated to control droplet size. The receiving capillary prevents the liquid droplet formation beyond a critical size, which reduces the volume of sampling compartment as compared with the case of the electrolyte flow driven solely by gravity. With a receiving capillary, the electrolyte droplet size was reduced from 1.5 to 0.46 mm. Further decrease of droplet size was not possible due to a so‐called droplet jump upwards effect which has been observed on a hydrophilic glass surface with water. A typical electrolyte used in CAEC has high methanol content. In an attempt to improve the methanol‐repellent properties of the glass surface, two approaches have been implemented: (i) self‐assembled chemisorbed monolayers of an alkylsiloxane and (ii) fabrication of a nano‐pin film. The methanol‐repellent surface of the feeding capillary suppressed the droplet jump upwards effect. The surface remained methanol repellent in different solutions with lower polarity than that of water.