Wednesday, October 2, 2019

Effect of Flow Rate on Retention Time in HPLC

Often throughout the chemical analysis of the sample mixture in chromatography, the number of components present has needed to be properly separated in a chromatogram; this is a complication in some cases. In these circumstances, the separation of the molecules of a sample solution is needed to complete before their detection in the detector. There are different analytical techniques are available to achieve this separation, the most commonly used method is high-performance liquid chromatography. 

The molecules are interacting differently with the stationary phase, resulting in varying their flow rates and separation. The affinity of each component of the adsorbent material relative to the mobile phase determines the retention time (RT) of the components, i.e., That is, the time to take by a molecule to separated from the column and detected by the detector (PDA, UV/VIS).

The retention time of the analytes depends on the flow rate, mobile phase composition, polarity, and pH of the buffer or mobile phase. The flow rate highly affects the retention time in HPLC, if the flow rate increases; it decreases the retention and if the flow rate decreases then it increases the retention of the sample. The flow rate is a useful tool to adjust the retention, but sometimes it affects system-suitability parameters such as theoretical plate number, tail factor, and peak symmetry.
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