Gradient Elution Is Used in HPLC

question 13

Multiple Choice

Gradient elution is used in HPLC.How is the gradient created for a reverse-phase HPLC experiment?

• A)Increase the pH of the mobile phase over time by adding strong base.
• B)Decrease the pH of the mobile phase over time by adding strong acid.
• C)Increase the vapor pressure of the analytes over time by increasing the temperature.
• D)Increase the polarity of the mobile phase over time by mixing with a more polar solvent.
• E)Decrease the polarity of the mobile phase over time by mixing with a less polar solvent.

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Definitions:

Immediate Reinforcement

The immediate reward or punishment following a behavior, which increases the likelihood of the behavior being repeated.

Respondent Behavior

A type of behavior that occurs as an automatic response to a specific stimulus, without voluntary control.

Pleasant Stimulus

An external factor that induces a positive emotional response or feeling of pleasure.

Positive Reinforcer

A stimulus when presented after a response increases the probability of that response being repeated, by providing a desirable effect or satisfying a need.