High performance capillary electrophoresis - T.E.A.M.

Modes
The versatility of MEKC is further exemplified by the
determination of organic gunshot and explosive constituents.
A separation of gunshot and explosive standards is
shown in figure 40. Here, qualitative characterization of six
reloading powders is made. Differences can be seen in each
manufacturer’s product reflecting the amounts of propellants,
stabilizers, and plasticizers. Ageing of powders also
gives rise to compositional changes. Overall, MEKC was
considered to be a superior technique for such analyses due
to excellent mass detection limits, low cost, rapid analysis
time, superior resolution, and extremely small sample
requirements. Further advantages included limited consumption
of expensive and hazardous reagents.
Figure 40
MEKC of extracts from different reloading
powders 20
Peaks: 1 = EtOH, 2 = nitroglycerin, 3 = 2,4-DNT,
4 = 2,6-DNT, 5 = diphenylamine, 6 = N-nitrosodiphenylamine,
7 = 2-nitrodiphenylamine,
8 = ethylcentralite, 9 = dibutylphthalate
Conditions: 2.5 mM borate, 25 mM SDS, pH
8.9, V = 20 kV, l = 50 cm, L = 67 cm,
id = 100 mm, l = 200 nm
2
7
8 9
6
1
5
3
4
0 2 4 6 8 10
Time [min]
3.3 Capillary gel
electrophoresis
Gel electrophoresis has principally been employed in the
biological sciences for the size-based separation of macromolecules
such as proteins and nucleic acids. The size
separation is obtained by electrophoresis of the solutes
through a suitable polymer which acts as a “molecular
sieve”. This form of zonal electrophoresis is illustrated in
figure 41. As charged solutes migrate through the polymer
network they become hindered, with larger solutes
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