Hanna Instruments HI 83099 - Manual (Page 61)

121 120 Silica
• Press the Zero key. The display will show “-0.0-” when the meter is zeroed and ready for measurement.
• Remove the cuvette and add the content of one packet of
HI 93705C-0 Amino acid reagent and shake until it is
completely dissolved.
• Reinsert the cuvette into the instrument.
• Press Timer and the display will show the countdown
prior to the measurement. Alternatively, wait for exactly
3 minutes and press
Read. When the timer ends the
meter will perform the reading. The instrument displays
concentration in
mg/L of silica (SiO
2
).
• Press ▲ or ▼ to access the second level functions.
• Press the
Chem Frm key to convert the result in mg/L of Silicon (Si).
• Press ▲ or ▼ to return to the measurement screen.
INTERFERENCES
Interference may be caused by:
Phosphate above 60 mg/L
Phosphate above 75 mg/L
Sulfide and high concentration of iron
Eliminate color and turbidity interferences by zeroing the meter with the original water sample.
Silica
SILICA
SPECIFICATIONS
Range 0.00 to 2.00 mg/L
Resolution 0.01 mg/L
Accuracy ±0.03 mg/L ±3% of reading at 25 °C
Typical EMC ±0.01 mg/L
Deviation
Light Source
Tungsten lamp with narrow band interference filter @ 610 nm
Method Adaptation of the ASTM Manual of Water and Environmental Technology, D859,
Heteropoly Blue method. The reaction between silica and reagents causes a blue tint in
the sample.
REQUIRED REAGENTS
Code Description Quantity
HI 93705 A-0 Molybdate 6 drops
HI 93705 B-0 Citric acid 1 packet
HI 93705 C-0 Amino acid 1 packet
REAGENT SETS
HI 93705-01 Reagents for 100 tests
HI 93705-03 Reagents for 300 tests
For other accessories see page 132.
MEASUREMENT PROCEDURE
• Select the Silica method using the procedure described in
the Method Selection section (see page 12).
• Fill the cuvette with 10 mL of unreacted sample (up to the
mark).
• Add 6 drops of HI 93705A-0 Molybdate reagent. Replace
the cap and swirl the solution.
• Wait for 4 minutes, add the content of one packet of
HI 93705B-0 Citric acid reagent and shake until it is
completely dissolved.
• Wait for 1 minute. This is the blank.
• Place the cuvette into the holder and close the lid.
10 mL