User Manual

44 45
• Reinsert the cuvette into the instrument.
• Press Timer and the display will show the countdown prior to the measurement or, alternatively, wait
for 6 minutes and press Read. When the timer ends the meter will perform the reading. The instrument
displays concentration in µg/L of chromium VI.
• Press s or t to access the second level functions.
• Press the Chem Frm key to convert the result in µg/L of Chromate (CrO
4
2
¯) and Dichromate (Cr
2
O
7
2
¯).
• Press s or t to return to the measurement screen.
INTERFERENCES
Interference may be caused by:
Vanadium above 1 ppm. However, waiting 10 minutes before reading, the interference is removed.
Iron above 1 ppm
Mercurous and mercuric ions cause slight inhibition of the reaction.
Chromium VI LR
Chromium VI LR
CHROMIUM VI LOW RANGE
SPECIFICATIONS
Range 0 to 300 µg/L
Resolution 1 µg/L
Accuracy ±1 µg/L ±4% of reading at 25 °C
Typical EMC ±1 µg/L
Deviation
Light Source Tungsten lamp with narrow band interference filter @ 525 nm
Method Adaptation of the ASTM Manual of Water and Environmental Technology, D1687-92 ,
Diphenylcarbohydrazide method. The reaction between chromium VI and the reagent
causes a purple tint in the sample.
REQUIRED REAGENTS
Code Description Quantity
HI 93749-0 Powder reagent 1 packet
REAGENT SETS
HI 93749-01 Reagents for 100 tests
HI 93749-03 Reagents for 300 tests
For other accessories see page 128.
MEASUREMENT PROCEDURE
• Select the Chromium VI LR 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)
and replace the cap.
• Place the cuvette into the holder and close the lid.
• Press the Zero key. The meter 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
93749-0 reagent. Replace the cap and shake vigorously for
about 10 seconds.
10 mL