Direct determination of amino acids and carbohydrates by high-performance capillary electrophoresis with refractometric detection

This is an initial report to propose a novel approach in high-performance c apillary electrophoresis (HPCE) for the direct detection of compounds witho ut natural absorbance in the UV and visible spectral range, such as amino a cids and carbohydrates. A refractometry detector with the 2 nl cell (Applie d Systems, Minsk, Belarus) was employed to identify amino acids and carbohy drates without derivatization. The first results are provided on separation of seven free amino acids in the phosphate running buffer and three free c arbohydrates in the borate-sodium dodecyl sulfate running buffer and detect ion by refractometer. Fused capillaries of 50 or 75 mu m internal diameter and separation voltage (10-23 kV) were applied. Detection limits ranged typ ically from 10 to 100 fmol and the response was linear over two orders of m agnitude for most of the amino acids and carbohydrates. The HPCE system dem onstrated good long-term stability and reproducibility with a relative stan dard deviation, less than 5% for the migration time (n=10). (C) 2000 Elsevi er Science BN. All rights reserved.