Monday, March 23, 2009

HPLC Broad Peak Causes and Solutions

High Performance Liquid Chromatography broad peak causes and solutions for this problem.

Cause Solution

Analytes eluted early due to sample overload Dilute sample 1:10 and reinject
Detector-cell volume too large Use smallest possible cell volume consistent with sensitivity needs; use detector with no heat exchanger in system
Injection volume too large Decrease solvent strength of injection solvent to focus solute; inject smaller volume
Large extra column volume Use low- or zero-dead-volume endfittings and connectors; use smallest possible diameter of connecting tubing (<0.10>
Mobile-phase solvent viscosity too high Increase column temperature; change to lower viscosity solvent
Peak dispersion in injector valve Decrease injector sample loop size; introduce air bubble in front and back of sample in loop
Poor column efficiency Use smaller-particle-diameter packing, lower-viscosity mobile phase, higher column temperature, or lower flow rate
Retention time too long Use gradient elution or stronger isocratic mobile phase
Sampling rate of data system too low Increase sampling frequency
Slow detector time constant Adjust time constant to match peak width
Some peaks broad - late elution of analytes retained from previous injection Flush column with strong solvent at end of run; end gradient at higher solvent concentration

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