1) Consider the peaks for pentafluorobenzene and benzene in the gas chromatogram shown here.  The elution time for unretained solute is 1.06 min.  The open tubular column is 30.0 m in length and 0.530 mm in diameter, with a layer of stationary phase 3.0 μm thick on the inner wall.   a) Find the adjusted rentention times and rentention factors for both compounds.  b) Find the relative rentention  c) Measuring the w1/2 on the chromatrogram , find the number of plates,  N1 and N2, and the plate height for these two compounds.

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1) Consider the peaks for pentafluorobenzene and benzene in the gas chromatogram shown here.  The elution time for unretained solute is 1.06 min.  The open tubular column is 30.0 m in length and 0.530 mm in diameter, with a layer of stationary phase 3.0 μm thick on the inner wall.  

a) Find the adjusted rentention times and rentention factors for both compounds. 

b) Find the relative rentention 

c) Measuring the w1/2 on the chromatrogram , find the number of plates,  N1 and N2, and the plate height for these two compounds. 

14.77 min
n-C,Hie
14.56 min
12.98 min
13.20 min
13.81 min
13.00
13.50
Time (min)
14.00
14.50
Transcribed Image Text:14.77 min n-C,Hie 14.56 min 12.98 min 13.20 min 13.81 min 13.00 13.50 Time (min) 14.00 14.50
TABLE 23-2 Summary of chromatography equations
| Quantity
Partition coefficient
Equation
Parameters
K= cJc.
c, = concentration of solute in stationary phase
Cm = concentration of solute in mobile phase
1, = retention time of solute of interest
= retention time of unretained solute
4, = volume flow rate = volume per unit time
V, = volume of stationary phase
V = volume of mobile phase
1, = time solute spends in stationary phase = 1,- 1.
, = time solute spends in mobile phase
Adjusted retention time
Retention volume
Retention factor
V, =1, 4,
k = r.- KV/Vm
Relative retention (also
a =
Subscripts I and 2 refer to two solutes
called separation factor)
w = width at base
win = width at half-height
16
5.55
Number of plates
N=
win
Plate height
G = standard deviation of band
H =
x= distance traveled by center of band
L = length of column
N= number of plates on column
N
Ar,
AV.
Ar, = difference in retention times
AV, = difference in retention volumes
W = average width measured at baseline in same units
as numerator (time or volume)
Resolution
Resolution
VN (a - 1)
N= number of plates
a = relative retention
k = retention factor for second peak
Resolution =
(1 + k2
Transcribed Image Text:TABLE 23-2 Summary of chromatography equations | Quantity Partition coefficient Equation Parameters K= cJc. c, = concentration of solute in stationary phase Cm = concentration of solute in mobile phase 1, = retention time of solute of interest = retention time of unretained solute 4, = volume flow rate = volume per unit time V, = volume of stationary phase V = volume of mobile phase 1, = time solute spends in stationary phase = 1,- 1. , = time solute spends in mobile phase Adjusted retention time Retention volume Retention factor V, =1, 4, k = r.- KV/Vm Relative retention (also a = Subscripts I and 2 refer to two solutes called separation factor) w = width at base win = width at half-height 16 5.55 Number of plates N= win Plate height G = standard deviation of band H = x= distance traveled by center of band L = length of column N= number of plates on column N Ar, AV. Ar, = difference in retention times AV, = difference in retention volumes W = average width measured at baseline in same units as numerator (time or volume) Resolution Resolution VN (a - 1) N= number of plates a = relative retention k = retention factor for second peak Resolution = (1 + k2
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