23
• Mark the vial with a pencil on the
white band to place an orientation
sign. Use this sign to insert the test
vial always in the same position into
the holder.
•
Place the vial into the holder and
push it completely down.
•
Press ZERO and “SIP” will blink on the display.
•
Wait for a few seconds and the
display will show “-0.0-”. Now the
meter is zeroed and ready for
measurement.
•
Remove the vial.
•
Remove the cap and add 4 drops of
HI 93764-0 Nessler Reagent.
• Replace the cap tightly and mix by
inverting the vial a couples of times.
This is the sample.
•
Place the vial into the holder and
push it completely down. Ensure that
the vial orientation respect to the
holder is the same as the blank.
• Press TIMER and the display will show the countdown prior to the
measurement. Alternatively, wait for 3 minutes and 30 seconds
and press READ DIRECT. In both cases "SIP" will blink during
measurement.
Ammonia LR
58
• The instrument directly displays concentration in
mg/L of
phosphate
(PO
4
3-
) on the Liquid Crystal Display.
• To convert the reading to mg/L of P
2
O
5
, multiply by a factor of
0.748.
• To convert the reading to mg/L of phosphorus (P) concentration,
multiply by a factor of 0.326.
Note
: for accurate measurements
1) wash glassware only with phosphate-free detergents
2) clean all glassware with 1 : 1 hydrochloric acid solution and rinse with
deionized water.
INTERFERENCES
Interference may be caused by:
Arsenate: at any level
Silica:
above 50 mg/L
Sulfide:
above 6 mg/L.
To eliminate sulfide: add Bromine Water drop-wise until a
pale yellow color develops; remove Bromine Water excess
by adding Phenol solution drop-wise.
Turbidity: turbidity and suspended matter in large amounts may
cause interference because the reaction conditions may
dissolve suspended matter or cause desorption of
phosphates from particles. Turbidity or suspended matter
should be removed before measurement by treatment
with active carbon and by prior filtration.
Phosphorus, Reactive