Hach DR/850 Procedures Manual page 342

PHOSPHONATES,
5.
Add the contents of
one Potassium
Persulfate for
Phosphonate Powder
Pillow to the cell labeled
as "sample". Swirl to
mix. This cell contains
the prepared sample.
continued
6.
Insert the ultraviolet
(UV) lamp into the
prepared sample.
Note: Wear UV safety
goggles while the lamp is on.
Note: Do not handle the
lamp surface. Fingerprints
will etch the glass. Wipe
lamp with a soft, clean
tissue between samples. Do
not use detergents with
phosphates to wash
glassware.
Note: A specially designed
cord adapter is available
for performing two
digestions with a single
power supply. A second UV
lamp is required.
7.
Turn on the UV lamp
to digest the prepared
sample.
Press:
TIMER ENTER
A 10-minute reaction
period will begin.
Note: Phosphonates are
converted to ortho-
phosphate in this step.
Note: The digestion step
may take less time.
Contaminated samples or a
weak lamp could result in
incomplete digestion.
Check efficiency by
running a longer digestion
to see if readings increase.
342
8.
When the timer
beeps, turn off the UV
lamp. Remove it from
the sample cell.