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Waters

"Invalid Curve" message in the calibration window for a GPC processing method in Empower 3 - WKB22693

Article number: 22693

SYMPTOMS

  • Molecular weights are calculated without issue
  • Calibration curve is created and present, but a message says "Invalid Curve, Do Not Use for Quantification" 

ENVIRONMENT

  • Empower 3
  • GPC analysis

CAUSE

The V0 and Vt times are not set properly in the processing method. 

FIX or WORKAROUND

Decrease the Vt so that the distribution is within the limits of the standard retention times.

ADDITIONAL INFORMATION

The V0 and Vt define the limits of calculation for the broad unknowns. When V0 and Vt are not used, the molecular weights are only calculated inside the boundary set by the retention times of the highest and lowest MW standards. If the distribution is wider than the limits of the standard retention times, the polydispersity will be too low because the high and low portions of the distribution are not calculated. 

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