Hach DR/700 Procedures Manual page 314

POLYACRYLIC ACID,
continued
INTERFERENCES
Filter turbid or oily samples through glass wool or a moderately rapid
paper, such as S&S No. 560, before beginning the test.
If the sample is laden with oil, do a preliminary extraction of the oil with
1,1,2-trichloro-1,2,2-trifluoroethane (Freon 113) as follows:
a) Transfer a sample portion to a clean 125-mL separatory funnel.
b) Add 10 mL Freon 113 to the funnel. Stopper. Shake vigorously for
two minutes, occasionally lifting the stopper to release pressure inside
the funnel. After shaking, remove the stopper. Allow the funnel to stand
undisturbed for 10 minutes while the layers separate.
c) Drain and discard the bottom (Freon) layer containing the oil.
Repeat, if necessary, to remove all visible oil.
d) Continue with Step 1 of Sample Preparation.
The test works in brines having levels as high as 75,000 mg/L total
dissolved solids (TDS) and 20,000 mg/L chloride. Minimize the effect of
most interferences by flushing the LC cartridge after the polyacrylic acid
is adsorbed on the column. Prepare 30 mL of demineralized water
buffered with 0.5 mL of Buffer Solution, pH 2.5. Repeat Steps 7 to 11 in
the Sample Preparation section with this solution. Continue with Step 12.
Samples with concentrations of less than 1 mg/L should be repeated.
Use two 20-cc volumes (instead of one) of the sample through the
cartridge in Sample Preparations Step 10 to 11. Continue with Step 12.
(This will require filtering two 30-cc volumes of sample in Step 2.).
Divide the resulting concentration by two. Up to five 20-cc volumes of
the sample can be run through the LC cartridge. It may be necessary to
flush the LC cartridge as stated above.
Avoid use of facial tissue when drying glassware or apparatus, as it may
contain interfering substances. Kimwipes or Kaydry wipers are
recommended.
SUMMARY OF METHOD
Polyacrylic acids (pAA) in the sample are selectively adsorbed onto a
liquid chromatographic column using a technique developed by Rohm
50-64