IonPac CS14 Manual
Doc. No. 034848-10
Page 38 of 54
5.18 Methanesulfonic acid / 18-Crown-6 Gradient Elution of Alkanolamines with Group I & II
Cations
The IonPac CS14 can be used to monitor the amine content in the quality control of chemical additives, process solutions,
plating baths, and scrubber solutions. To optimize resolution, the 18-Crown-6 ether complexing agent can be added to the
eluent as illustrated in this example. This chemical forms a strong complex with monovalent cations such as potassium,
ammonium and ethanolamine. These complexes are very highly retained, increasing the retention times of these cations. Due
to the differences in the degree of complexation and the selectivity of the resin for the complexes, the elution order of the ions,
ethanolamine and ammonium, and ethanolamine and triethanolamine, are reversed. This technique can be useful for the
determination of alkanolamines in the presence of high ammonium or potassium concentrations since these two analytes elute
late.
The determination of monoethanolamine, triethanolamine and other alkanolamines in the presence of ammonia, Group I & II
cations can be accomplished by gradient elution using 5 mM methanesulfonic acid (MSA) as the initial eluent and then
stepping to 21 mM methanesulfonic acid (MSA) after 12 minutes.
This eluent can be suppressed using the AutoSuppression Recycle Mode. To convert the column back to eluents without 18-
Crown-6 ether, wash the column with an acetonitrile/DI water gradient from 5% to 40% acetonitrile, hold for 20 minutes, and
then equilibrate to the new operating conditions. Carefully flush all lines and fittings used with the 18-Crown-6 eluent.
Sample Loop Volume:
6.25 µL (2-mm), 25 µL (4-mm)
Analytical Column:
IonPac CS14 Analytical Column
Eluent:
See Chromatogram
Eluent Flow Rate:
0.25 mL/min (2-mm), 1.0 mL/min (4-mm)
SRS Suppressor:
Cation Self-Regenerating Suppressor, CSRS ULTRA (2-mm or 4-mm)
Recycle Mode
or MMS Suppressor:
Cation MicroMembrane Suppressor, CMMS III (2-mm or 4-mm)
MMS Regenerant:
100 mN TBAOH
(tetrabutylammonium hydroxide)
Expected Background Conductivity:
< 1 µS
Storage Solution:
Eluent
Eluent 1:
Type I DI Water
Eluent Flow Rate:
1.0 mL/min
Eluent 2:
10 mM MSA
(4-mm System)
Eluent 3:
100 mM MSA
Eluent 4:
10 mM 18-Crown-6
TIME (min)
%E1
%E2
%E3
%E4
Comments
Equilibration
0.0
45
30
0
25
Equilibrate to 3.0 mM MSA / 2.5 mM 18-Crown-6
10.0
45
30
0
25
Analysis
0.0
45
30
0
25
Inject, 3.0 mM MSA / 2.5 mM 18-Crown-6
0.1
45
30
0
25
Inject Valve to Load Position
10.0
45
30
0
25
3.0 mM MSA / 2.5 mM 18-Crown-6
15.0
35
0
40
25
40 mM MSA / 2.5 mM 18-Crown-6
35.0
35
0
40
25
40 mM MSA / 2.5 mM 18-Crown-6
35.1
45
30
0
25
3.0 mM MSA / 2.5 mM 18-Crown-6