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Aluminum
Aluminum
Page 4 of 6
a. Rinse a 50-mL graduated mixing cylinder and a 125-mL Erlenmeyer
flask containing a magnetic stir bar with 6 N hydrochloric acid
(Cat. No. 884-49). Rinse again with deionized water. This will remove
any aluminum present.
Note: Rinse two Erlenmeyer flasks if a reagent blank is used; see step b below.
b. Measure 50 mL deionized water into the 125-mL Erlenmeyer flask using
the graduated cylinder. This is the reagent blank. Because of the test
sensitivity, this step must be done only when any of the reagents used in
the following pretreatment are replaced—even if the new reagent has a
matching lot number. When the pretreated sample has been analyzed,
correct for the aluminum concentration of the reagent blank by touching
, then
Options
Reagent Blank
and touch
.
OK
c. Measure 50 mL sample into the 125-mL Erlenmeyer flask using the
graduated cylinder. Use a small amount of deionized water to rinse the
cylinder contents into the flask.
d. Add 4.0 mL of 5.25 N Sulfuric Acid Standard Solution (Cat. No. 2449-32).
e. Use a combination hot plate/stirrer to boil and stir the sample for at least
30 minutes. Add deionized water as needed to maintain a sample
volume of 20-40 mL. Do not boil dry.
f. Cool the solution to near room temperature.
g. Add 2 drops of Bromphenol Blue Indicator Solution (Cat. No. 14552-32).
h. Add 1.5 mL of 12.0 N Potassium Hydroxide Standard Solution
(Cat. No. 230-32) using the calibrated, plastic dropper provided. Swirl to
mix. The solution color should be yellow or green but not purple. If the
color is purple, begin with step a again using an additional 1 mL Sulfuric
Acid Standard Solution in step d.
i.
While swirling the flask, add 1.0 N Potassium Hydroxide Solution
(Cat. No. 23144-26), a drop at a time, until the solution turns a dirty
green color.
j.
Pour the solution into the graduated cylinder. Rinse the flask contents
into the graduated cylinder with deionized water (Cat. No. 272-56) to
bring the total volume to 50 mL.
k. Use this solution in step 3 of the ECR method.
Fluoride interference can be corrected by using the table on page 5.
Example:
If the fluoride concentration is known to be 1.00 mg/L F
gives a reading of 0.060 mg/L aluminum, what is the true mg/L aluminum
concentration?
Intermediate values can be found by interpolation. Do not use correction graphs
or charts found in other publications.
Answer: 0.183 mg/L
. Touch
. Enter the reagent blank value
On
–
and the ECR method
Aluminum_PP_Other_ECR_Eng_Ody.fm
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