21
5 mL x 2
• Remove the cap and fill the
Demineralizer Bottle with tap
water.
• Replace the cap and shake
gently for at least 2 minutes.
• Open the upper part of the
Demineralizer Bottle cap and squirt
gently the demineralized water into
the cylinder, up to the 100 mL mark.
Note: The ion exchange resin
contained in the Demineralizer Bottle
is provided with an indicator
substance. The indicator will change
from green to blue when the resin
has been exhausted and the resin
has to be replaced.
• Pour the solution in the large 170mL
beaker, replace the cap and invert
several times to mix.
• If the solution contains some turbidity
or color, add a powder packet of
active carbon and follow the
procedure described for
Irrigation
Water
.
NUTRIENTS SOLUTION (HR):
• Use the 5 mL syringe twice to add to
the graduated cylinder exactly 10
mL of sample.
Note:
To measure exactly 5 mL of
40
Phosphorus LR
x 10
• Wait for a few seconds and the
display will show "-0.0-". Now
the meter is zeroed and ready for
measurement.
• Remove the cuvet.
• Add 10 drops of HI 93706A
Molybdate reagent.
• Add the content of one packet of
HI 93706B Phosphorus Reagent
B (Amino Acid) to the cuvet.
Replace the cap and shake gently
until dissolution is complete.
• Reinsert the cuvet into the
instrument.
• Press TIMER and the display will show the countdown prior to the
measurement or, alternatively, wait for 5 minutes and press READ
DIRECT. In both cases "SIP" will blink during measurement.
• The instrument directly displays concentration in mg/L of phosphorus
(P) on the Liquid Crystal Display.
• To convert the reading to mg/L of phosphate (PO
4
3–
), multiply by
a factor of 3.07.
INTERFERENCES
Calcium above 10000 mg/L as CaCO
3
Chloride above 150000 mg/L as Cl
–
Ferrous iron above 100 mg/L
Magnesium above 40000 mg/L as CaCO
3
Sulfide
