Measuring 0.05 – 2.00 mg/l Cr
range: 0.11 – 4.46 mg/l CrO
4
Expression of results also possible in mmol/l and also in Cr total ( Cr), Cr(III), and Cr(VI).
114552
Cell Test
Chromate
Determination of total chromium
= sum of chromium(VI) and chromium(III)
Add 6 drops of Cr-3K
into a reaction cell,
close the cell with the
screw cap.
Shake the cell vigorous-
ly to dissolve the solid
substance and leave to
stand for 1 minute.
Place the cell into the
cell compartment. Align
the mark on the cell with
that on the photometer.
Quality assurance:
To check the measurement system (test reagents,
measurement device, and handling) ready-f
or-use
chromate standard solution Certipur
®
, Cat.No. 119780,
concen tration 1000 mg/l CrO
4
2–
, can be used after diluting
accordingly.
Add 5.0 ml of the pre-
treated sample
with
pipette
, close with the
screw cap, and mix.
Pipette 10 ml of the sam-
ple into an empty round
cell (Empty cells, Cat.No.
114724).
Add 1 drop of Cr-1K,
close with the screw cap,
and mix.
Add 1 dose of Cr-2K
using the blue dose-
metering cap, close the
reaction cell with the
screw cap.
Heat the cell in the
thermoreactor at 120 °C
(100 °C) for 1 hour.
Remove the cell from
the thermoreactor and
place in a test-tube rack
to cool to room tempera-
ture:
pretreated sample
.
A differentiation between chromium(VI) and
chromium(III) can be performed on the pho-
tometer. Prior to measuring, select the differ-
entiation measurement and choose the corre-
sponding citation form. Then measure the
total chromium (result for “Cr total” is shown
on the display), press enter and measure the
chromium(VI) (see analytical procedure for
chromium(VI)). The
individual measuring val-
ues for Cr VI and Cr III
are shown on the dis-
play.
Reaction time:
1 minute
Check the pH of the
sample, specified range
:
pH 1 – 9.
If required, add dilute
sodium hydroxide
solution or sulfuric acid
drop by drop to adjust
the pH.
Release 06/2014 - Spectroquant
®
UV/VIS Spectrophotometer Pharo 300
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