DIODE LASER-BASED DETECTION IN LIQUID-CHROMATOGRAPHY AND CAPILLARY ELECTROPHORESIS

Detection techniques involving diode lasers are increasingly of intere st in separation science. Diode lasers are small and inexpensive and h ave a very stable output. However, diode lasers emitting at wavelength s shorter than 635 nm are not commercially available. This seriously l imits the applicability of direct detection, since few analytes absorb at such long wavelengths. Because devices that emit at much shorter w avelengths are not expected to become available in the near future, in direct detection schemes involving diode lasers are being developed. T hese are often based on derivatization with redabsorbing labels and su bsequent separation of the label and the various derivatized analytes using either liquid chromatography (LC) or capillary electrophoresis ( CE). The application of diode-laser-based detection in CE is of partic ular interest because the usual detection methods, e.g., absorption de tection, do not have the sensitivity required for many applications.