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Test: HPLC scientist

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1) Which of the following statements is correct?

The capacity factor is:

- Independent of the peak shape.

- Independent of the type of mobile phase used.

- Increasing with increasing peak width.

- Almost independent of the solvent used to dissolve the analyte.

 

 

 

2)  When the particle diameter of the stationary phase decreases, keeping all other physical characteristics of the column equal, it will have the following effect: Which of the following statements is incorrect?

- The pressure in the system increases.

- The capacity factor increases.

- The peak width decreases.

- The mass transfer to the stationary phase is facilitated.

 

 

 

3) The enthalpy of adsorption to the stationary phase can be determined by measuring the capacity factor as a function of temperature. Which equation is used in the evaluation of the data?

 

- Navier-Stokes equation

- van Deemter equation

- Arrhenius equation

- van´t Hoffs equation.

 

 

 

4)  Which of the follwing statements is correct:

 

- The relation k´= F*K ( F = column phase ratio; K = adsorption constant ) is independent of the type of adsorption isotherm.

- For a protolytic analyte the shape of the adsorption isotherm is the same for the unionised and ionised form.

- In non-linear chromatography the determined peak shape is usually determined by the adsorption isotherm.

- When the column is overloaded the stationary phase is saturated with analyte.

 

 

 

5) For a protolytic organic molecule the capacity factor in RP-chromatography is usually lower for the ionised form than for the unionised form. The reason for this is that:

 

 -The dielectric constant for the stationary phase is lower than for the mobile phase.

- The ionised form is the most polar form.

- The polarisibility of the ionised form is higher.

- Only the unionised form can adsorb to the stationary phase.

 

 

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