441
Method 8196
VOLATILE ACIDS (0 to 2800 as mg/L HOAc) For digestor sludges
Esterification Method
*
* Adapted from The Analyst, 87, 949 (1962)
1. Enter the stored
program number for
Volatile Acids as acetic
acid (HOAc).
Press:
PRGM
The display will show:
PRGM ?
Note: For most accurate
results, perform a Reagent
Blank Correction using
deionized water (see
Section 1).
2. Press: 96 ENTER
The display will show
mg/L, HOAc and the
ZERO icon.
Note: If high levels of
dissolved solids or mineral
acids are present, distill as
described in the Hach
Distillation Apparatus
manual.
3. Pipet 0.5 mL of
deionized water into a
dry 25-mL sample cell
(the blank).
Note: Use a Class A or
TenSette Pipet.
Note: Adjust the pH of
stored samples before
analysis.
4. Filter or centrifuge
25 mL of the sample.
Note: Centrifugation is
faster than filtration.
5. Pipet 0.5 mL of the
filtrate or supernatant
into another dry 25-mL
sample cell (the
prepared sample).
Note: Use a Class A or
TenSette Pipet.
6. Pipet 1.5 mL of
ethylene glycol into each
sample cell. Swirl
to mix.
7. Pipet 0.2 mL of
19.2 N Sulfuric Acid
Standard Solution into
each cell. Swirl to mix.
8. Place both cells into
a boiling water bath.
Note: Samples may be
boiled in a 600-mL beaker.
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