Waters IC-Pak Ion Exclusion Columns - Manual (Page 5)

[ Care and Use ManUal ]
5 Waters IC-PAK ™ Ion Exclusion Columns
c. Eluent Preparation
10 mM Octanesulfonic Acid Concentrate
1. To a 254 mL beaker add 2.163 g of the sodium salt of
octane sulfonic acid (98% Aldrich) and dissolve in 100 mL
Milli-Q water.
2. Add 100 mL of precleaqned cation exchange resin in the
H+ form (BloRad AG 50W-X12, 200-400 mesh, or equiva-
lent) and stir in the resulting slurry for 10 minutes.
3. Filter the resin, rinsing with approximately 800 mL of
Milli-Q water, into a one liter volumetric flask. Dilute up to
the mark with Milli-Q water.
Note: This 10 mM oc tanesuffonic acid solution istable for at least
one month.
1 mM Octanesulfonic Acid Eluent (pH3)
1. Into a one-liter volumetric flask add 100 mL of the octane-
sulfonic acid concentrate.
2. Fill the flask to the mark with Milli-Q water and mix
thoroughly.
3. Filter and degas through a 0.45 µm HA filter.
The H+ ion from the acid influences the separation. The acid’s
counter-anion has no effect but to after the background conductivity.
Thus, other strong acids can be substituted for octanesulfonic acid.
Note: Acid Normality should be kept constant.
Weak organic acids can also be detected by direct UV absorption in
the 205 nm to 215 nm range.
d. Standard Preparation
1. Prepare 1000 ppm stock standards from their sodium salts
2. For this working standard, dilute:
0.1 mL of 1000 ppm Fluoride
0.5 mL of 1000 ppm Formate
1.0 mL of 1000 ppm Acetate
1.0 mL of 1000 ppm Propionate
1.0 mL of 1000 pnm Butyrate
to 100 mL with MHH-Q water.
Note: This working standard should be prepared weekly, since the
formate concentration decreases with time.
Symptom Cause Corrective Action Prevention
Buildup in HPLC system
operating pressure
Inlet frit plugged with
particulates
Clean and regenerate column (see Sec-
tion V. b.). Check for injector and pump
seal shedding.
Always filter the eluent and sample prior to
use. Use an in-line filter between the pump and
injector.
Guard-Pak insert clogged
with particulates or
adsorbed materials
Replace the spent Guard-Pak insert.
Replace the
Guard-Pak inserts more frequently.
Fluctuating
backpressure
Gas in the eluent
Check degassing procedure, Displace
gas from the pump.
Always degas the eluent prior to use.
Spurious peaks
Weakly dissociated
inoganic anions can
sometimes coellute with
carboxylic acids
Analysze your sample for carbonate,
sulfite, or other anions using an IC-Pak
anionn column.
Modify sample preparation.
Variable elution times Variation in flow rate or
eluent composition
Check flow rate being delivered. Check
eluent composition.
Always throughly mix eluents prior to use.
Band broadening or loss
of resolution
Guard-Pak insert fouled Replace spend Guard-Pak insert.
Replace
Guard-Pak inserts more frequently.
Column fouled or old
Clean and regenerate the column
(see Section V. b.). If column does not
recover, use a new column.
Isolate the source of the contamination and use
a Guard-Pak insert to protect the column from
contaminants in the sample.
Table 2. Problems and Corrective Actions