... heating,
microparticles of silica spherical composit
e
Figure 5.10 Aggregation of microparticles to form totally porous particles.
212 THE COLUMN
and the particles are strengthened by sintering. Small particles ... preparing totally porous silica particles is to aggre-
gate or assemble microparticles, as illustrated in Figure 5.10. One such procedure
is to disperse a silica sol of define...
... reader
may wish to skip this digression, proceed to Section 7. 2.1.2, andreturntothepresent
section as needed.
We can define the ‘‘effective buffer capacity’’ of the mobile phase to mean that
an ... peak is seen in Figure 7. 5 for a mobile-phase pH = 3.0.
As the pH increases to 3.5 (Fig. 7. 5b) and 4.0 (Fig. 7. 5c), the peak progressively
broadens and becomes more distorted (peak f...
... (min)
Time
(
min
)
Time
(
min
)
02468
Time (min)
02468
4
5
7
6
4
5
6
7
1
2
3
4
5
6
7
4
5
7
6
0 2 4 6 8 0 2 4 6 8 10 12
4
+
5
7
6
4
+
5
7
6
(a)
(b)
(c)
(d)
(e)
(f )
Figure 7. 15 IPC separation of a sample of water-soluble ... From
these initial experiments (Fig. 7. 15a–c), it appears that a hexane sulfonate concen-
tration of 6 to 7 mM would provide maximum resolution of peak...
... × 4.0-mm silica column (5-μm particles); 1.5% methanol-methylene chloride; 25
◦
C;
1mL/min.(a) Fresh sample; (b) degraded sample of polymer (stored at pH -7. 4 and 37
◦
C for 60
days); (c) degraded ... required
to achieve the desired retention range of 1 ≤ k ≤ 10, as well as to take advantage of
solvent-strength selectivity.
At the conclusion of exploratory TLC studies with silica plates...
... behavior can make it
extremely difficult to obtain reproducible isocratic separations of macromolecules in
different laboratories, or even within the same laboratory. Furthermore the isocratic
separation ... separations by RPC (with fixed run times,
for automated analysis) are only practical by means of gradient elution and are
commonly used to assay combinatorial libraries [3], as well as...
... need to be
applied to this value before the final sample concentration is reported.
11.4 QUANTITATIVE ANALYSIS 521
it in water or buffer to make a primary stock. This stock then is added to the ... 11.8 to 11.10 for Same Analyte and Separation Conditions
Response
Concentration (ng/mL) External Standard
a
Internal Standard
b
Standard Addition
c
0 4 87
1 215 0.0408 72 9
2 416 0. 078...