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

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

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

21. Why is source modulation needed in atomic absorption spectroscopy? (1) to create a double-beam configuration for the spectrometer, (2) to separate the emission signal of the analyte in the flame from the emission of the fuel and oxidant in the flame, (3) to create a AC type of signal for the flame emission, (4) to create a DC type of signal for the light source, (5) to create a AC type of signal for the light source. Your answer: (A)1,2,4 (B)1,5 (C)1,4 (D)1,2,3 (E)5

22. In the ICP-MS technique which of the following ionization method is utilized? (A) Electrospray (B) MALDI (C) Electron impact (D) High temperature in an inert atmosphere (E) Reaction with Ar atoms

23. Which of the following techniques is not correct in producing X-rays? (A) bombardment of a metal target with a beam of high-energy electrons (B) use of a radioactive source to excite a metal target (C) excitation of a metal target through chemical reactions (D) from a synchrotron radiation source (E) irradiation of a metal target with a primary X-ray source

24. Why is the graphite furnace AA technique more sensitive than the flame AA technique for most of the transition metals? (1) the sample amount is larger for furnace AA； (2) the average residence time of atoms in furnace is much longer than in the open flame； (3) the steady-state concentration of atoms in the flame is much lower than in the furnace； (4) the flame temperature is higher than furnace's； (5) the detector of furnace AA is more sensitive. Your answer: (A)2,3,5 (B)2,3 (C)4,5 (D)1,4,5 (E)3,4

25. The interferometer is used in FT-IR (1) to act like a grating in a monochromator, (2) to scan wavelengths from low to high, (3) to facilitate FT because the IR frequencies are too high to be acquired by average-cost electronics, (4) to resolve IR frequencies into a series of sine and cosine functions, (5) to produce an identical time-domain spectrum of much lower frequencies. Your answer: (A) 1,2 (B)1, 2,4 (C)3,4 (D)3, 4,5 (E)5