Waters IC-Pak C Method Development Column - Manual (Page 4)

[ Care and Use ManUal ]
Waters IC-Pak C M/D Column 4
General considerations
• Filter all aqueous buffers. Do not use turbid or cloudy buffers.
• Do not reuse aliquots taken from the sample container; dispose of
them.
• Protect the column from vibration, mechanical shock, and rapid
changes in pressure, flow rate or mobile phase composition. Any
thermal, physical or chemical shock (such as changing mobile phases
rapidly) can cause a loss of efficiency.
• When using water, treat it with a water system capable of delivering
18 megohm water. Neither deionized water nor HPLC-grade bottled
water are acceptable because they may contain organic compounds
which alter column selectivity.
• Highly concentrated samples (greater than 10 ppm per ion) can
overload the packing material, resulting in poor peak shape. Dilute
the sample before injection. When analyzing an unknown, start with a
1:100 dilution.
• DO NOT inject concentrated samples directly into the mobile phase.
Direct injection may cause precipitation of the salts in the sample.
Dissolve (or dilute) samples in an appropriate volume of the mobile
phase first. If you must use other solvents, watch for precipitation upon
injection into the eluent. Always filter samples before use.
b. Efficiency Testing
Perform on efficiency test before attempting the first analysis.
Run the test sample using the calibration standards detailed in the
following pages. Record the retention time and the settings used
There are four parts to performing the efficiency test:
1. Preparing the mobile phase
2. Preparing the stock calibration standards
3. Running the calibration (working) standard
4. Calculating column efficiency
If you experience problems during normal operation, repeat the
conditions for the initial efficiency test and compare the results.
Differences may indicate a problem with the column.
Preparing Mobile Phase
The IC-Pak C M/D column uses 0.1 mM EDTA/3.0 mM HNO 3 as a
mobile phase. See phase Section III. a, Preparing the Mobile Phase,
for procedures for mobile phase preparation.
Guidelines for the Calibration Standard
Standard concentrates are available from most major chemical
suppliers. Use reagent-grade or analytical standard-grade
solutions. Several anionic species can cause the precipitation of
alkali and alkaline earth metals. Consult solubility tables to avoid
these species. Avoid hygroscopic salts. Select the highest purity
salt available. Certain atomic absorption standards are made
from ammonium salts and must not be used to prepare calibration
standard.
Preparing Individual 1000 ppm Stock Standards
1. Weigh the specified amount of salt (refer to Table 1).
2. Add the salt to a plastic 1 liter volumetric flask.
3. Fill the flask to the mark with 18 megohm water.
4. Store the stock solutions in clean plasticware at room temperature for
up to 6 months.
Table 1: Salt Weight for Stock Solution Preparation
The following equation is an example of how these weights were
determined:
1 g K + /L x 74.553 g KCI/39.100 g K + x 1 L = 1.9067 g KCI
Cation Compound Weight (g)
Li + (Lithium) UOH • H
2
0 6.0476
No + (Sodium) NaCI 2.5421
NH
4
+ (Ammonium) NH
4
CI 2.9640
K + (Potassium) KCI 1.9067
Mg
2
+ (Magnesium) Mg(NO
3
)
2
• 6H
2
0 10.5466
Ca
2
+ (Calcium) Ca(N0
3
)
2
• 4H
2
0 5.8919
Sr
2
+ (Strontium) Sr(NO
3
)
2
• 4H
2
0 3.2377
Ba
2
+ (Barium) BaCl
2
• 2H
2
0 1.7786