9. Problems caused by dissolved air in mobile phase
o Unstable delivery in pump
o Bigger noise and large baseline-drift in detector cell
In order to avoid causing the problems, mobile phase
should be degassed.
9
13. Partial-filling
o The volume of the sample loaded is limited to half the
sample loop volume.
Complete-filling
o In order to replace all the mobile phase in the loop,
excess sample (two to five loop volumes) must be
used.
13
15. Isocratic system
o Fixed (un-changeable) mixing ratio during analysis
Gradient system
o Changeable mixing ratio during analysis
• HPGE (High Pressure Gradient)
• LPGE (Low Pressure Gradient)
15
30. 1. Adequate sensitivity
2. Good Stability and Reproducibility
3. A linear response to analytes that extends over several orders
of magnitude
4. A short response time that is independent of flow rate
5. High reliability and ease of use
6. Similarity in response toward all analytes or alternatively a
highly predictable and selective response toward one or more
classes of analytes
7. Nondestructive of sample
8. Minimal internal volume in order to reduce zone broadening
30
31. Material
o Stainless steel (SUS)
o PEEK (Polyether ether ketone)
Size
O.D. (Outer Diameter)
o 1.6 mm
I.D. (Inner Diameter)
o 0.1 mm
o 0.3 mm
o 0.5 mm
o 0.8 mm etc.
31
32. Male nut (SUS)
Ferrule (SUS)
o Pressure: up to 40 MPa
Male nut (PEEK)
o can be connected without
any tools
o Pressure: up to 25 MPa
32
Male nut
Ferrule
Male nut (PEEK)
33. Water
o Ultrapure water
o HPLC grade
Organic solvent
o HPLC grade
o Super-high grade may be
used in some application.
o Some solvents such as THF
and chloroform include
Stabiliser, which cause a
problem.
33
34. Un-dissolved solvents
must not be used in
replacement.
Buffer must not be
replaced directly with
organic solvent.
34
Water
Hexane
2-Propanol
Buffer
Organic solvent
Water
35. Stationary phase Mobile phase
Normal
phase
High polarity
(hydrophilic)
Low polarity
(hydrophobic)
Reversed
phase
Low polarity
(hydrophobic)
High polarity
(hydrophilic)
35
36. Polarity
o (+) and (-) charges
exist in a molecule.
Water: polar
Methane: nonpolar
Solubility
o Similar solvents can be
easily soluble.
o Polar/Nonpolar
molecules are similar to
Water/Oil.
36
O
H H
–
+
C
H H
H
H
Water methane
37. Stationary phase: Low polarity
o ODS (Octadecyl silane) column
Mobile phase: High polarity
o Water, Methanol, Acetonitrile
o Buffer
37
45. 1. It is sensitive
2. It is readily adaptable to accurate quantitative determinations
3. It is suitable for separating nonvolatile species
4. It is suitable for separating thermally fragile species
5. Due to its widespread applicability to substances that are of
prime interest to industry, to many fields of science and to the
public.
45
46. • Confidence in the Analytical Method and the Result
produced is important.
• What is confidence?
• The method should have been validated prior to the
Analytical Investigation i.e. thoroughly tested to show
that the method gives ACCURATE results for the type of
sample being analysed.
• If we are concerned about the ACCURACY of a result, then it
is obvious that concern should extend all the way from
SAMPLING to the publication of the final RESULT.
46
47. • Thus what areas would you consider to be important in
producing an ACCURATE analysis?
• The sampling procedure should produce a representative
sample
• The sample should not become contaminated or alter
chemically during storage
• There should be no contamination of the sample within the
laboratory or during the analysis
• Any losses in extraction, separation and concentration
procedures should be minimized
47
48. • There should be no interference in the final analysis from
other components in the sample.
• Results should be correctly calculated and archived for
future reference.
• Thus the overall methodology needed or employed to
minimize the potential errors is referred to as QUALITY
ASSURANCE.
• The measures employed to ensure the validity of
individual results is referred to as QUALITY CONTROL
48
49. 1. Sampling and sample storage procedures which ensure
that the sample is truly representative and that it reaches
the laboratory unchanged
2. Sampling and analysis in duplicate
3. Specifications within the analytical scheme for reagent
purity and apparatus cleanliness
4. Repeated checks on the instrument performance
5. Traceability in any standards used. This means that the
stated concentrations in any standard used must be
traceable back to primary international standards
49
50. 6. Inclusion in each analytical batch of additional of
additional samples of known composition. These will
confirm the RELIABILITY of the method and could include
the ff:
a. Blank Samples – samples made up as close as possible in
composition to the unknown, excluding the compound being
determined. These are introduced before stages in the in the
analysis when contamination is likely. A positive determination of
the analyte in the blank would indicate contamination.
b. “Spiked” Samples – these are samples to which a known quantity
of the compound being determined has been added. A valid
analysis of the spiked and unspiked sample will be able to
determine accurately the quantity added.
50
51. Certified Reference Materials (CRMs) – these are
materials similar in type to the unknown sample and
have an accurately determined composition.
51