Carryover observed in ACQUITY UPLC (classic) system - WKB54764

SYMPTOMS

• Carryover observed in ACQUITY UPLC system.

ENVIRONMENT

• ACQUITY UPLC

CAUSE

Compound being analyzed is not soluble in the wash solvents or initial eluant conditions.

FIX or WORKAROUND

1. Change wash solvents or initial mobile phase conditions to match compounds being analyzed.

ADDITIONAL INFORMATION

1. Change the strong wash solvent to one compatible solvent for analysis. Strong wash should be:
   • Miscible with weak wash.
   • Strong enough to dissolve and remove any traces of sample from sample flow path.
     • Adding some formic acid can help for very sticky, hydrophobic compounds.
     • Add THF if absolutely necessary for analysis.
2. Replace weak wash with a compatible solvent for analysis. Weak wash should be:
   • Miscible with strong wash.
   • Close to initial mobile phase conditions in terms of organic strength.
   • Close to sample diluent in terms of organic strength (particularly important for partial loop pressure assist injections).
3. Change initial conditions of the gradient to a composition more suited to analysis. Initial gradient conditions should be:
   • Relatively close to sample diluent in terms of organic strength (particularly important with larger injection volumes).
   • Polar or nonpolar enough to match analysis and sample type.