Volatile Acids Esterification Method - Hach DR/850 Procedures Manual

VOLATILE ACIDS
Esterification Method
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).
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.
* Adapted from The Analyst, 87, 949 (1962)
(0 to 2800 as mg/L HOAc)
*
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.
6.
Pipet 1.5 mL of
ethylene glycol into each
sample cell. Swirl
to mix.
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.
7.
Pipet 0.2 mL of
19.2 N Sulfuric Acid
Standard Solution into
each cell. Swirl to mix.
441
Method 8196
For digestor sludges
4.
Filter or centrifuge
25 mL of the sample.
Note: Centrifugation is
faster than filtration.
8.
Place both cells into
a boiling water bath.
Note: Samples may be
boiled in a 600-mL beaker.