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Assessing solvent correction curves

Solvent correction curves plot the reference-subtracted response against the response on the reference surface for injections of buffer containing a range of solvent concentrations. The curves are fitted to the experimental points using a second-degree polynomial expression. In this way, the contribution of solvent to the reference-subtracted response is calibrated as a function of the bulk response on the reference surface.

Solvent correction curves obtained from two separate solvent correction cycles

In general, solvent correction curves have a negative slope and are slightly curved. Variations in slope and curvature are normal. Consider the following points when deciding whether to apply solvent correction:

• How well does the curve fit the experimental points?
  If isolated points deviate from the curve, exclude those points.
  If the points scatter with significant deviations, do not use the curve.
  Applying solvent correction with a badly fitted correction curve can introduce more errors than the correction is designed to address.
• What is the range of reference response covered on the x-axis?
  Ideally, there should be eight solvent correction points spread over an interval of 1000-1500 RU. If the range of the x-axis is greater than 1500 RU, you have used too widely spaced solvent concentrations in the run. You may still be able to use the curves if they are of sufficiently good quality.
• Is the range of response values adequately covered?
  The range of report point values that are candidates for solvent correction is indicated by vertical red lines on the curves. Response values that lie outside the range of the correction curves will not be corrected. Do not extrapolate the solvent correction curves by more than about 10% of the range on the x-axis.
• How much correction will be applied?
  Examine the extent of correction (read from the y-axis) that will be applied for the range of report point values in the data. If the report point range is narrow and/or the curve slope is shallow so that the correction range is small, applying solvent correction will not make much difference to the evaluation.

See also

List of help files

Solvent correction