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Inverse Gradient for Uniform Response

The Thermo Scientific Dionex Corona ultra charged aerosol detector provides universal and nearly uniform response for non- and semivolatile analytes under isocratic conditions. Under gradient conditions, it shows increased detection response with increasing organic content in the mobile phase. This is common for all nebulizer-based detectors. Inverse Gradient for Uniform Response is a Thermo Scientific Dionex UltiMate 3000 x2 Dual system-based UHPLC+ solution that enables a uniform detection response of non- and semivolatile compounds with the Dionex Corona ultra detector even when using gradient elution.

The great benefit of uniform detection response is that semiquantitative analysis is possible with a single, universal calibration. Unknowns with or without chromophores are easily quantified, without information about the chemical structure and without expensive standard substances.

A uniform response with a nebulizer-based detector such as the Dionex Corona ultra requires a constant composition of the mobile phase. An easy solution to this is a second flow path with an inverse gradient. This does not compromise the detection sensitivity as the Dionex Corona detectors are mass-sensitive detectors, not concentration sensitive. The dual-gradient pump of a Dionex UltiMate 3000 x2 Dual system feeds a second flow path connected to a t-piece placed in front of the Dionex Corona ultra detector. This flow path can be established with a Thermo Scientific Dionex nanoViper used as a restriction capillary between the second pump and the t-piece.

  • The response factor is kept uniform during gradient analysis by adding an inverse gradient in front of the detector inlet
  • Adding the inverse gradient does not change the detector sensitivity since the Dionex Corona ultra is a mass sensitive detector
  • A second gradient pump is a default component of a Dionex UltiMate 3000 x2 Dual system
  • The Dionex Viper Inverse Gradient Kit for Uniform Response contains all required Dionex Viper and Dionex nanoViper capillaries for setups with or without column