Download Basics of Chromatography - Instrumental Analytical Chemistry - Lecture Slides and more Slides Analytical Chemistry in PDF only on Docsity! Basics of Chromatography • Separation of Analytes • Type of Equilibrium M S C CK = Docsity.com Basics of Chromatography • Ability to dissolve in mobile phase • Interaction with stationary phase • Time on X axis • Response on Y Docsity.com • Retention time of the analyte • Retention time of the Mobile Phase Docsity.com Basics of Chromatography • Average linear flow rate • Average linear flow of mobile phase Rt L =ν Mt L =µ Docsity.com • Plate Height • Theoretical Measure of Efficiency L H 2σ = Docsity.com Basics of Chromatography • The Van Deemter Equation H = A + B/u + Cu Docsity.com t ABLE 26-3 Kinetic Processes That Contribute to Peak Broadening
Term in Relationship to Column*
process Equation 26-19 and Analyte Properties
Multiple flow paths A A= dp
B 24D
Longitudinal diffusion Bhu ; = 7 iM
fill dj
Mass transfer to and from Cyu Cy = D f u
liquid stationary phase s,
(ed,
Mass transfer in mobile phase Cyt Cgit = i Ey |
M
RN
#4, Ds Duy dp dp Hf ate 88 defined in Table 26-2.
f= function of x.
A, yt constants that depend on the quality of the packing.
B: coefiicient of longitudinal diffusion.
Cy, Chg: coefficients of muss transfer in stationary and mobile phases, respectively.
Docsity.com
Flow
direction
|
jcneeeenteneee ND) ¢ Multiple Flow Paths
¢ Tortuosity
Figure 26-8 Typical puthaays of two molecules during
ution, Note that distance traveled by molecule 2 is
gleater than that traveled by molecule , Thus, molecule 2
Would arrive at B later than molecule 1.
® Docsity.com
• How Plate Height is effected by particle size in solid packing Docsity.com Basics of Chromatography • Column Efficiency H LN = 2)( W tN R= 2 2 1 )(54.5 W tN R= Docsity.com Resolution
Detertor signal
ii
7 Gra AZ
Ayr ls
ve + ha
i
I
|
4 A,
0
Figere 26.11 Separations at tines resolutions. Here, Ry = ZAZKWa + Wr).
3 Docsity.com
Solute signel
More on Resolution
1 2 ta)
INSJ\_
Time
26-14 [liustration of the general elution problem tn chromatography.
Docsity.com
TABLE 264 [mportant Chromatographic Experimental Quantities and
Relationships
Name Symbol of Experimental Quantity Determined From
Migration time, nonretained species iy Chromestogram (Figure 26-6)
Retention tines, species A and B (tala, (fady Chromatogran (igus 2-6)
Adjusted retention time, species A (fala tiada = (pda ~ ty ,
Peak widths, species A and B Wa, We Chromatogram (Fiene 26-6)
Leapth of column packing E Direct measureanent
Flow rate F Direct measurement
Vohume of stationary phase Vy Packing preparation data
Concentration of analyt: in mobile tw Cs Analysis and preparation data
and stationary phases
B Docsity.com
TABLE 26-8 Important Derived Quantities and Relationships
Name Calculation of Derived Quantities Relationship to Other Qnantitia
Linear mobile- a= Diy
phase velocity
Yoluma of mobile Vy = te
phase
Retention factor = tig — inalltng K as
ie
i
T¥istribation constant k= Vn gn th
¥s ou
—_ i
Seloctivity factor = file = ta = fe -
(tala ~ fw kg My
: [tele ~ Uadal VN (2 - “i in
= =-——
Resolution Ry Wa + Wp R, 4 7 Nite
2 a \2
Number of plaics N= 1 BF N= 1623 a } 14
Ww, Wy &
Plate height =i
see o y (1+ ay
Retention t = _# Ct Ay
paseaion time tala u inl (a?
L) Docsity.com
