14. Under what circumstance would buoyance become a non-negligible factor and should be accounted for when using an analytical balance accurate to± 0.1 mg.
(A) Variation of the temperature in the laboratory
(B) The density of standard weights is 8.0 g/cm³ and the density of the object being weighed is 0.2 g/cm³
(C) The density of the object being weighed is 16 g/cm³
(D) Density has little role in buoyance consideration
(E) None of the above

10. Which of the following statements about the elution process of LC is not true? (A) In nornal-phase LC, the least polar analyte is eluted first because it is the most soluble in the mobile phase. (B) In normal-phase LC, a less polar solvent has higher eluent strength. (C) Increasing the polarity of the mobile phase has the effect of decreasing the elution time in normal-phase LC.(D) In reversed-phase LC, a more polar solvent has lower eluent strength. (E) In reversed-phase LC, increasing the mobile phase polarity increases the elution time of the less polar analyte.

11. For electrophoresis and electroosmosis, which of the following statement is not true? (A) Electrophoretic mobility is the constant of proportionality between the speed of the ion and electric field strength； (B) For ions with similar size in electrophoresis, their mobilities decrease with charges； (C) Electric double layer created by negatively charged silica surface and nearby cations； (D) For electroosmotic flow (EOF), net EOF toward the cathode when an external field is applied； (E) For capillary electrophoresis, the only fundamental source of broadening under ideal conditions is longitudinal diffusion.

12. An organic pollutant contents one bromines (Br) and two chlorine (Cl) in its structure. Estimate the possible ratio of the isotopic patterns on the molecular ion.Your answer: (A) 9:6:3:1； (B) 1:3:3:1； (C)37:5:1； (D)9:157:1. (E) None of the above

13. For Ion mobility spectrometers (IMS), which of the following statement is true? (A) IMS is a form of mass spectrometry； (B) Like mass spectrometry, IMS is not capable of separating isomers； (C) IMS separates ions according to their size-to-charge ratios； (D) IMS can provide structural information of analytes； (E) Cl2 is the reagent gas for generating cations by chemical jonization in IMS analysis.

15. Which of the following statements about the blank analysis is correct? (A) An ideal blank should be free of matrix. (B) An ideal blank is a solution containing solvents, reagents and analytes. (C) A field blank should never leave the laboratory to avoid contamination. (D) The step of blank analysis can be omitted if the sample solution is clear and homogeneous. (E) The signal from the blank should be subtracted from that of the sample when determining the concentration of analyte.

16. When the work of detecting systematic errors is required, which of the following practices can be performed? (1) analyzing standard reference materials (SRMs), (2) blank analysis, (3) independent analysis by other reliable methods, (4) compared with other laboratories using the same method, (5) using another instrument of a different maker/ manufacturer. Your answer: (A)1,2 (B)1,2,3 (C)1,3,4 (D)1,2,3,4 (E)1,4, 5

17. Which of the following statements is true? (A) Systematic errors can be determined and hence largely corrected. (B) Calculation of detection limits is a way to demonstrate accuracy. (C) Systematic error affects reproducibility and thus accuracy of the analytical results. (D) Random errors can be eliminated or improved with a chosen method. (E) Random errors can be corrected by calibration with standard reference materials.

複選題18. In order to correct for instrumental drift in analysis and to assure data quality, which of the following practices can be performed? (A) Standard addition (B) External standardization (C) Intemnal standardization (D) Spiking with a known amount of the analyte to calculate recovery (E) To regularly perform calibration check

19. When considering the propagation of uncertainty with a calibration curve from linear regression, which of the following approaches or conditions does not help narrow down the uncertainty (Sx) of the unknown concentration [X]? (A) to achieve a greater slope for the calibration curve (B) to have more data points for the calibration line (C) to increase the number of replicate measurements of the unknown (D) the signal or response of the unknown to be at the far ends of the calibration line (E) a correlation coefficient closer to unity

20. Which of the following statements regarding detection limits (D.L.) are false: (1) Only ~1% of measurements of a blank are expected to exceed theD.L. (2) If the analyte concentration is right at the D.L., then one is only 50% confident to say that the sample does contain analyte. (3) If the analyte concentration is right at theD.L., then one is 99% confident to say that the sample does contain analyte. (4) Measurements showing results below D.L. can suggest the sample does not contain analyte. (5) The probability of being false positive is ~1% for samples containing no analyte. Your answer: (A) 1,2,5 (B)1, 2, 4 (C)3,5 (D)2, 5 (E) 3,4