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Chemistry LibreTexts

Procedures: The Module

  1. Draw a schematic representation of a capillary electrophoresis system. Include instrumental components. Make the diagram as detailed as possible.
  2. How are analytes separated by free zone capillary electrophoresis? Describe the fundamental principles that govern the method.
  3. What type of detector will you use for this research project? What fundamental spectrophotometry principle(s) govern(s) analyte response in the detector?
  4. Define the following terms: quantitative, qualitative, mean, median, standard deviation, relative standard deviation, significant figure, linear range, dynamic range, reproducibility, limit of detection, limit of quantification, analyte, sample, standard, and calibration curve.





    Standard Deviation

    Relative Standard Deviation

    Significant Figures

    Linear Range

    Dynamic Range


    Limit of Detection

    Limit of Quantification




    Calibration Curve

  5. Write the standard operating procedure to make a stock solution of 1mM tolmetin dissolved in deionized water. Include a sample calculation.
  6. Write the standard operating procedure to dilute a 1mM stock solution of aqueous tolmetin to a final concentration of 100.μM. Note: the 100.μM tolmetin must be diluted in 50mM pH 7.0 N-tris(hydroxymethyl)methyl-2-aminoethanesulfonic acid (TES). Include a sample calculation.
  7. Mesityl oxide and tolmetin were separated using free zone electrophoresis under the following conditions: 50 micron i.d., 42 cm fused silica capillary, 50 mM pH 7.0 phosphate buffer, separation voltage 16kV, detection at 206 nm. Using the information provided below, report the mean migration time, mean peak height, mean peak area, mean plate count/meter for mesityl oxide as well as tolmetin. For each mean value determined, also report the standard deviation and relative standard deviation.
    Run # Analyte Migration Time Peak Width at Base Peak Height Peak Area

    mesityl oxide











    mesityl oxide











    mesityl oxide










    Mesityl Oxide

    Mean Migration Time = ____ (SD = ____ RSD =___ %)

    Mean Peak Height = ____ (SD = ____ RSD =___ %)

    Mean Peak Area = ____ (SD = ____ RSD =___%)

    Mean Plate Count/Meter = ____ (SD = ____ RSD =___ %)


    Mean Migration Time = ____ (SD = ____ RSD =___ %)

    Mean Peak Height = ____ (SD = ____ RSD =___ %)

    Mean Peak Area = ____ (SD = ____ RSD =___%)

    Mean Plate Count/Meter = ____ (SD = ____ RSD =___ %)

  8. List the compounds of interest for the first phase of research.
  9. By what mechanism(s) do the compounds comprising the answer to question 8 separate via capillary electrophoresis?
  10. You are given three samples to analyze using a capillary electrophoresis-UV-visible absorbance system. Sample A contains ascorbic acid and mesityl oxide, sample B contains tolmetin and mesityl oxide, sample C contains mesityl oxide and either ascorbic acid or tolmetin. All analyte are at a concentration of 100 micromolar TES buffered at pH 7. Outline the procedure you would use to analyze these samples with your instrument and determine the identity of the analyte peaks in sample C. Assume you have access to standards if necessary. Provide rational for your outlined procedures. Note any anticipated difficulties you might encounter.
  11. Write a standard operating procedure for entering information into your laboratory notebook.
  12. You are trying to separate a sample that contains both mesityl oxide and ascorbic acid. What is the order of migration of each analyte? (i.e. which analyte comes off the capillary first?) Explain/justify your answer.
  13. How do you determine the identity of analyte peaks in an electropherogram?
  14. How do you determine the concentration of analyte in a sample using CE-UV-visible absorbance detection (assume no sample matrix effects)?
  15. Why is flushing/rinsing the capillary important? What flush/rinse procedures should you use?
  16. What safety hazards must you consider before beginning this project?
  17. Write the standard operating procedure to analyze the samples listed below using flow injection analysis with your CE-UV-visible absorbance instrument. Analytes: mesityl oxide, tolmetin, atenolol.
  18. What is the molecular weight of each analyte listed below? Analytes: mesityl oxide, tolmetin, atenolol.
  19. What is the net charge of each analyte in aqueous solution buffered at pH 7.0? Analytes: mesityl oxide, tolmetin, atenolol.
  20. In a conventional free zone capillary electrophoresis system (i.e. anode at injection end, cathode at detection end), what is the order of migration of the following analytes: mesityl oxide, tolmetin, atenolol (assume background electrolyte is aqueous, buffered at pH 7.0)?
  21. Write the standard operating procedure to analyze the sample listed below using free zone capillary electrophoresis with your CE-UV-visible absorbance instrument. Be sure to include protocol for injection, detector operation, and flushing/rinse. Sample contains the following analytes: mesityl oxide, tolmetin, atenolol.
  22. Provide an electropherogram of a single sample containing the following three analytes: neutral marker (mesityl oxide or dimethylformamide), tolmetin, atenolol, each at a concentration of 100 micromolar. Note, this solution must be diluted with background electrolyte. Identify each peak in the electropherogram. Indicate how you verified the identity of each peak experimentally.
  23. Using the electropherogram provided for question 22, complete the following information:


run name:

notebook entries:

background electrolyte:

flushing protocol:

run date and time:

computer filename:

capillary dimensions:

injection duration:

separation voltage:

detection wavelength:

detection rise time:

injection pressure:

separation current:

detection range:

tolmetin migration time:

tolmetin width (σ)

tolmetin peak height:

tolmetin plate count:

neutral marker migration time:

neutral marker width (σ)

neutral marker peak height:

neutral marker plate count:

atenolol migration time:

atenolol width (σ)

atenolol peak height:

atenolol plate count: