课程名称︰ 分析化学二 课程性质︰ 化学系必修 课程教师︰ 陈俊显 开课学院： 理学院 开课系所︰ 化学系 考试日期（年月日）︰ 100.6.20 考试时限（分钟）： 120 是否需发放奖励金： 是 （如未明确表示，则不予发放） 试题 : 姓名(name)：__________________ 学号(student ID)：____________________ 课号：203 21220, Spring 2011, Exam #3 (2011-06-20) 10:20 ~ 12:05 (满分130 分：乘40%为期末总成绩积分) page 2-1 助教会在收卷前5 分钟(12:05)提醒各位。 试卷请缴回；有问题请举手招呼助教(不要念出题目来)，由助教趋近回答； 若有需要，助教会向同学宣布。 I. (84%) Multiple Choice Questions (Select one answer and write it on this sheet above the underlines.) (3 points for a correct answer, –1 point for a wrong answer, mark △ if you think that there is no correct answer) (单选，每题3 分，答错倒扣1 分，若你认为选项中没有正确答案，则打△) ___ 1. Which of the following does NOT lead to zone broadening in chromatography? a) Faster flow rates. b) Slower flow rates. c) Smaller column diameters. ___ 2. Decreasing the thickness of the stationary phase leads to: a) decreased plate height, decreased retention time, and decreased capacity for the analyte. b) decreased plate height, decreased retention time, and increased capacity for the analyte. c) decreased plate height, increased retention time, and decreased capacity for the analyte. 3–4. Chromatograms shown below are obtained from two columns with equal length and at the same linear flow rate. ___ 3. Which of the following comparison between Columns A and B is correct? a) Column 1 has more theoretical plates. b) Column 1 has a larger relative retention. c) Column 1 has a larger capacity factor. ___ 4. Which of the following comparison between Solutes A and B is correct? a) Solute A has a larger capacity factor. b) Solute A has a smaller partition coefficient. c) Solute A has a smaller concentration in the sample. ___ 5. The column capacity factor k' can be easily adjusted by: a) changing the eluent linear flow rate. b) changing the solvent strength of the eluent. c) changing the column pressure. ___ 6. Which of the following is an ideal value for the capacity factor in chromatography? a) 1. b) 5. c) 30. ___ 7. For the separation of two solute in a column whose length and inner diameter are fixed, reducing the size of the packing particles will a) reduce the diffusion coefficient of solutes in the stationary phase. b) improve the RS for the solutes. c) increase the selectivity factor, R_s, for the solutes. ___ 8. Which of the following may lead to the possibility of both increase and decrease the plate height of a column? a) Increasing the weight of the stationary phase relative to the packing weight. b) Decreasing the column temperature. c) Increasing the injection port temperature. ___ 9. Which of the following is the most common carrier gas for GC? a) He. b) N2. c) H2. ___ 10. Split-injection often used in capillary GC because it has a) a very sensitive detector. b) a large selectivity factor. c) a small capacity factor. ___ 11. An "on-column injection" is used a) when a very small amount of analyte is present in the sample. b) when the injection chamber is under splitless mode. c) when the solute vaporization takes places at 50 oC or more above the column temperature. ___ 12. Which of the following decreases the plate height of a GC column? a) decreasing the weight of the stationary phase relative to the packing weight. b) decreasing the rate of sample injection. c) decreasing the volume flow rate. ___ 13. Which of the following detector is a mass-sensitive detector? a) FID. b) TCD. c) ECD. ___ 14. Solutes containing halogens can best be studied in gas chromatography with a) FID. b) TCD. c) ECD. ___ 15. Which of the following detectors would provide greatest sensitivity for the detection of CO2? a) FID. b) TCD. c) ECD. ___ 16. The reason why HPLC has the "high performance" is because a) it uses a high-pressure pump to drive the eluent. b) it uses small particles which reduce the contribution of A and C terms to the plate height. c) there is only B term left in the van Deemter equation. ___ 17. Which of the following is usually used as a preparative step that mainly to isolate a single compound from a complex mixture? a) Ion chromatography. b) Affinity chromatography. c) Molecular exclusion chromatography. 18–20. Find the most suitable LC for each of the following cases. Possible methods are a) bonded reversed-phase chromatography b) adsorption chromatography c) bonded normal-phase chromatography d) ion-exchange chromatography e) molecular/size exclusion chromatography f) affinity chromatography. a 18. solute: formal weight < 2000, soluble in octane c 19. solute: fw < 2000, soluble in dioxane, but not CHCl3 e 20. solute: fw > 2000, , soluble in THF, size 50 nm ___ 21. Based on Table 23-3, please predict the elution order from a column containing (diphenyl)0.35(dimethyl)0.65polysiloxane. Which of 1-butanol, hexane, and benzene will have the shortest tR? a) 1-Butanol. b) Hexane. c) Benzene. ___ 22. For a benzene/acetone gradient used in a normal-phase column, a) the sample component that forms hydrogen bonding most easily is eluted first. b) the lowest molecular weight sample component is eluted first. c) the % of benzene decreases as the column is eluted. ___ 23. Which of the following is NOT a common approach to improve the stability of silica-based solid support? a) The use of triethylamine additive in the eluent. b) The use of bulky isobutyl groups at the siloxane headgroup. c) The use of bidentate alkyl siloxanes. ___ 24. In the selection of a detector for a chromatographic method utilizing gradient elution, reasonable choices would include: a) ultraviolet detector, refractive index detector, or an electrochemical detector. b) ultraviolet detector, fluorescence detector, or mass spectrometry. c) refractive index detector, electrochemical detector, and conductivity detector. ___ 25. In the case of separation of K+ and Ca2+ from mixture of KNO3 and CaSO4 by ion chromatography, a) the separation column is a strong-base anion exchanger. b) the suppressor column is a strong-base anion exchanger. c) the separation column is a strong-acid anion exchanger. ___ 26. For the preparation of resins for ion chromatography, an increase of the percentage of divinylbenzene a) will increase the rigidity of the resins. b) will decrease the ionic interactions between the resins and the analytes. c) can provide better protection to the solid support against hydrolysis. ___ 27. In gel-permeation chromatography, there is a linear relationship between: a) molecular mass and log of the migration time. b) molecular radius and log of the retention volume. c) retention volume and log of the molecular mass. ___ 28. Which of the following pH 5.0 eluents (phosphate) would give the longest migration time for alkaline ions in CZE? (cathode@detector) a) 30 mM b) 0.50 M c) 0.80 M phosphate. 有关於II~IV 的评分：需要叙述的地方，描述必须完整，才能获高分； 仅提供关键字、文意不明的句子则不给分。 II. (23%) (a) Write the full name of the following acronyms, and (b) answer the question(s) following the acronym. (i) (6%) SPME; Should all the analyte in an unknown be extracted into the fiber in SPME? Why or why not? (ii) (5%) HPLC; Why is high pressure needed in HPLC? (5%) What is an "evaporative light-scattering detector"? Why is the detector compatible with gradient elution? (iii) (7%) HILIC; why is eluent strength increased by increasing the fraction of water in the mobile phase? III. (13%) Method Development for Reversed-Phase Separations. (i) (3%) State one method for measuring tM in reversed-phase chromatography. (ii) (3%) What does the "four solvents" mean? (iii) (3%) How to use the nomographs? (iv) (4%) How to optimize the solvent composition for the separation? IV. (10%) Ion chromatography. Please quantitatively show how the suppressor improves the signal of the K+ zones by using the table in the right. (Eluent: HCl; c_pre,A: concentration for A species prior to suppressor; c_after,A: concentration for A species after suppressor; e.g. c_pre,H+, c_after,H+, c_pre,Na+, c_after,Na+, ... ...) ion (S‧m2/mol) H+ 350 Na+ 50 K+ 74 OH- 198 CO3 2- 138.6 HCO3- 44.5 Cl- 76 ※ 编辑: satisfy64ING 来自: 140.112.24.42 (06/28 23:00)