110年 - 110 國立清華大學碩士班考試入學試題_分析與環境科學研究所:分析化學#104989

1. (5%) A new automated procedure for determining glucose in serum (Method A) is to be compared with the established method (Method B). Both methods are performed on serum from the sarne six patients to eliminate patient-to-patient variability. Do the following results confirm a difference in the two methods at the 95% confidence level?

2. (5%) The analysis of a calcite sample yielded CaO percentages of 55.95, 56.00, 56.04, 56.08, and 56.23. The last value appears anomalous; should it be retained or rejected at the 95% confidence level?
(To answer this question, please refer to the statistics table at the bottom of this page.)

3. (10%) A 0.9092-g sample of a wheat flour was analyzed by the Kjeldahl method. The ammonia formed was distilled into 50.00 mL of 0.05063 M HCl; a 7.46-mL back-titration with 0.04917 M NaOH was required. Calculate the percent of protein in the flour. (Note: The nitrogen-to-protein conversion factor for cereals is 5.7)

4. (4%) What types of species can be separated by HPLC but not by GC?

5. (5%) Describe the working principle of quadrupole mass analyzer.

6. (6%) How does gas-liquid chromatography work? List the variables that lead to band broadening in gas-liquid chromatography.

7. (3%) Indicate the order in which the following compounds wound be eluted from an HPLC column containing a reversed-phase packing: acetone, dichloroethane, acetamide.

8. (4%) Why is atomic emission more sensitive to flame instability than atomic absorption or fluorescence?

9. (4%) Explain the working principle of the cold vapor atomic absorption spectroscopy to determine mercury.

10. (8%) What is the purpose of an internal standard in ICP-MS? List the characteristics that are often cited as requirements for a good internal standard.

11. (4%) Explain why molecular fluorescence often occurs at a longer wavelength than the exciting radiation.

12. (5%) Quinine in a 2.196-g tablet was dissolved in a sufficient 0.10 M HCI to give 1.000 L. Dilution of a 20.00-mL aliquot to 100 mL gave a solution with a reading of 540 at 347.5 nm. A second 20.00-mL aliquot was mixed with 10.0 mL of 50 ppm quinine solution before dilution to 100 mL. The fluorescence intensity of this solution was 600. Calculate the concentration in parts per million of quinine in the tablet.

(a) Describe the working principle of voltammetry.

(b) Suggest how the Equation list below could be employed to deternine the number of electrons involved in a reversible reaction at a voltammetric electrode.

(a) the transmittance and absorbance of the absorbing solution.

(b) the transmittance to be expected if the light path through the original solution is doubled.

15. (7%) (a) Describe the source of pH-dependence in a glass membrane electrode. (b) The cell
has a potential of 0.2094 V when the solution in the right-hand compartment is a buffer of pH 4.006. The following potential is obtained when the buffer is replaced with an unknown solution: -0.2910 V. Calculate the pH and the hydrogen ion activity of the unknown solution.

16. (5%) Following two figures are the absorption spectra of transition and rare earth ions. Apparently, these two spectra differ substantially from each other. Please state the reason why the absorption spectra of transition and rare earth ions are different.

(a) What are the structural characteristics of a chelating agent?

(b) Why are multidentate ligands preferable to unidentate ligands for complexometric titration?

18. (10%) How would you prepare 1.0 L of a buffer with a pH of 9.45 from 0.3 M Na₂CO₃ and 0.2 M HCI? (Na₂CO₃:)

110年 - 110 國立清華大學碩士班考試入學試題_分析與環境科學研究所:分析化學#104989

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