2003. 5. 9
(I)Distinguish the following techniques from the points of theory,
instrumentation, as well as adventages and shortages. (9%*3=27%)
(A)Spectroscopy:AAS,AES and AFS
(B)Atomizers:Flame,furnace,and Plasma
(C)Background correction:D2,Smith-Hieftje,and Zeeman
(II)Yes-No question(credit is only counted with a correct support) (2%*10=20%)
(A)AES provides a lower detection limit for sodium than for copper.
(B)Phosphate effect is more significant on the determination of Ca using
ICP than using flame.
(C)Internal standard method is a good way to improve the reproducibility in
the determination of potassium when using AES.
(D)A conventional light source such as Xe lamp is commonly used in AAS,
(E)CsCl is a common ionization suppressor in the analysis of sodium.
(F)A pached column provides higher efficiency than an open tubular column.
(G)Modification of the capillary wall is a common way to improve efficiency
when analyzing organic acids.
(H)Plate jeight generally increases with increasing flow rate when using an
open tubular column.
(I)The capacity factor of the stationary phase used to seperate sodium from
potassium.
(III)Linewidth (2%*5=10%)
(A)The magnitudes of atomic absorption line and Molecular adsorption band
(B)Three main factors for line broadening in atomic absorption line
(C)At constant pressure,is the linewidth of an atom broader in ICP than
that in flame?
(D)At constant temperature,is the linewidth of an atom broader in flame
than that in furnace?
(E)How does the lifetime of an excited state of an atom affect linewidth if
at least two factors in question (B) exist?
(IV)Using a 30.0-m open tubular column(nonpolar stationary phase)to separate
methanol,phenol,benzene,and pentafluorobenzene,the elution times are 0.5,
12.5,13.0,and 14.0 min. The bandwidths in the baseline are 10,12,15,and 20
s ,respectively. (2%*10=20%)
(A)Find the capacity factors for benzene.
(B)Find the selectivity between phemol and benzene.
(C)Find the resolution between phenol and benzene.
(D)Find the efficiency (number of plate) for benzene.
(E)Find the plate height for benzene.
(F)What is the efficiency for benzene if the column length is 120m?
(G)what is the plate height for benzene if the column length is 15m?
(H)How about the plate height for benzene if the column diameter is 2 times
wider?
(I)How about the bandwidth for benzene if the column length is 120 m?
(J)How about the bandwidth for benzene if the injection volume is 6 times
larger?
(V)The temperature in ICP-AES can be as high as 8000度C. Suggest one optical
method to estimate the temperature of the plasma. (4%)
(VI)For the extraction of Cu2+ by dithizone in CCl4, KL=10^4,KM=10^5,Ka=10^-6
,β=10^23 ,and n=2. (4%*3=12%)
(A)Calculate the distribution coefficient for extraction of 0.1μM Cu2+
into CCl4 by 0.1mM dithizone at pH 2.0 and 5.0.
(B)If 100mL of 0.1μM aqueous Cu2+ is extracted once with 10mL of 0.1mM
dithizone at pH 2.0,what fraction of Cu2+ remzins in the aqueous phase?
What is the fraction if five extractions were conducted using 2mL 0.1mM
dithizone under the same condition?
(C)Derive an equation to show how you can determine the formation constant
and the stoichiometry between Ni2+ and dithizone.
(VII)Plot the plate height vs.floe rate according to van Deemter equation
(You must show individual plate height and their sum vs. flow rate and
identify them) (8%)
(VIII)The interferometer mirror of a FTIR travels ±0.5cm (2%*5=10%)
(A)How many centimeters is the maximum retardation?
(B)What is the approximate resolution of the instrument?
(C)At what retardation interval must the interferogram be sampled to cover
a spectral range of 0 to 2000cm-1 ?
(D)Use plots (spectra) to show the difference between interferogram and
transmission spectrum.
(E)Why is FTIR more sensitive than conventional IR?
Total:111%
--
※ 發信站: 批踢踢實業坊(ptt.csie.ntu.edu.tw)
◆ From: 61.223.88.40