• Universal - Detects any non-volatile analyte.
• Gradient Elution - Not restricted to isocratic elution conditions.
• High Sensitivity - Limits of on-column detection in the low nanogram range. Less than 100 pg in micro HPLC.
• Low Temperature Operation - 40°C with 100% water at a flow rate of 2 ml/min.; 35°C with most organics at a flow rate of 2 ml/min.
• Low Gas Consumption - Less than 3 L/min.
• Solvent Transparent - Can be used with any solvent, including strong UV absorbers. Does not produce solvent front peaks.
• Stable - Insensitive to fluctuations in ambient conditions.
• Versatile - The same unit can be used in HPLC, micro HPLC or SFC with appropriate interchangeable nebulizers.
• Safe - The instrument design insures total safety in case of carrier gas flow interruption.
• Self Cleaning - Requires minimal maintenance due to extremely low surface contamination. Cleaning is effected by temperature programming without dismantling the drift tube.

Effluent from the chromatographic column is nebulized to form a homogeneous mist of droplets. This aerosol then enters a heated tube where the mobile phase evaporates, leaving non-volatile analytes. The residual analytes then reach the optics of the detector system, where they diffuse through an incidental light beam from a tungsten-halide source.

The light scattering caused by the non-volatile analyte(s) is collected by a photomultiplier and converted to an analog signal which is output to a signal recording device. The amount of diffused light, A, is a function of the mass, m, of the analyte and this generally obeys an exponential relationship A = am^b. Thus, a plot of log A versus log m should give a linear response. The slope of this line, b, and the constant, a, are dependent on both the nature of the mobile phase and the temperature at which evaporation takes place.

Generally, a greater response is obtained at lower temperatures, and the SEDEX ELS detectors are unique in that they can effectively evaporate all solvents at temperatures significantly below their boiling points.

For analytes that are polar, ionizable or ionic, it is possible to add volatile modifiers to the mobile phase, to improve chromatographic performance. Such modifiers include ammonium hydroxide, triethylamine, ammonium acetate, Formic, acetic, trifluoroacetic acids and nitric acid.

For greater resolution, gradient elution can also be employed. The versatile SEDEX ELS detectors may be used in preparative applications, by means of an optional flow-adiustable stream-splitting device. For micro HPLC, a micro HPLC kit is available. For SFC applications, an SFC kit is available.