Hach Lange 2100AN, Instrument Manual

Page: 83 / 108

SECTION 9,
continued
83
9.2.2 Tips for Color Measurement
•
Reestablish the analytical zero reference point (re-zero) for the best possible
accuracy and reproducibility. Repeat this procedure when a measurement is
not taken for several hours.
•
Best accuracy and reproducibility are achieved using a Flow-Cell Kit (see
SECTION 5 on page 49). A Flow-Cell system is required to meet the stated
instrument specifications. If a Flow Cell is not used, match sample cells using
the %T or Absorbance modes and the procedure described in Section 2.3.4.2
on page 22).
•
Color, %T and Absorbance measurements use the same “Zero” reference
point. The Absorbance, %Transmittance and Color Unit measurement modes
are re-zeroed simultaneously. Color, Absorbance and %Transmittance can be
measured on a single sample after establishing a zero reference in any of the
three modes.
9.2.3 Using Transmittance Units (Transmittance 100% Procedure)
A blank solution (100% transmittance) must be read before the transmittance
reading mode can be used. This normally is DI water. After inserting an
appropriate color filter in the instrument, transmittance is set to 100% by the
following procedure:
1. Select transmittance by pressing the
UNITS/EXIT
key until the units display
shows “%T.”
2. Press the
CAL/ZERO
key to select 100 %T.
3. The main display flashes
100%
, and the mode display reads
00
. Insert the
blank solution, close the cell cover, and press
ENTER
to read the blank. The
display counts down from 30 to 0 while the blank is being read. The display
reads 100 %T after time expires.
4. Install a sample cell filled with the sample to be measured.
The %Transmittance result is shown on the large display.
9.2.4 Using Absorbance Units (Absorbance Zero Procedure)
A blank solution (zero absorbance) must be read before the absorbance reading
mode can be used. This normally is DI water. After inserting an appropriate color
filter in the instrument, absorbance is zeroed by the following procedure.
1. Select absorbance by pressing the
UNITS/EXIT
key until the units display
shows
A
.
2. Press the
CAL/ZERO
key to select the zero.
3. The main display flashes
ZERO
, and the mode display reads
00
. Insert the
blank solution, close the cell cover, and press
ENTER
to read the blank.
The display counts down from 30 to 0 while the standard is being read. The
display reads
0.000 A
after time expires.
4. Install a sample cell filled with the sample to be measured. The absorbance
result is shown on the large display.