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Macro 900 Operation Manual
Full two-point calibration should be carried out every few months.
15.4.4.
Calibration Solution Preparation
In order to 'calibrate' (actually, set the relative sensitivity) of the CPHYLL
probe, a 500µg/L calibration solution of fluorescent dye known as Rhodamine
WT should be used.
Please note: there is no direct correlation between Rhodamine concentration
and the concentration of chlorophyll. Rhodamine is used as a convenient dye
for setting the sensitivity of the sensor. The subsequent display of chlorophyll in
terms of mg/L is a generalisation based on research and experience. The only
way to obtain a true value in terms of cells/L is to correlate the values from the
Probe to quantitative data that has been obtained by laboratory analysis of grab
samples. See previous 'Limitations of Use' section.
The 500µg/L calibration solution should be freshly prepared by serial dilution
from 200g/L standard using deionised water. The following Rhodamine WT
standard is recommended:
Be sure to handle chemicals with care and to read and comply with all
health and safety advice.
15.4.5.
Serial Dilution
The recommended Rhodamine solution is supplied as a 20% or 200g/L solution,
dilution of the stock solution should be carried out as follows.
200g/L stock → 500μg/L is recommended to be done as a two-step dilution
procedure.
Step 1: weigh out 0.5g of 200g/L stock solution in a weigh boat and add this to
1L of deionized water in a volumetric flask, use some of the water from the 1L
flask to rinse the weigh boat so no stock Rhodamine remains on the boat. Put
a lid on the 1L flask and invert 10 times.
This step results in a 1 in 2000 dilution of the stock, at this point the 1L flask
will contain a 100mg/L solution.
Step 2: Transfer 5ml of the 100mg/L solution to a 1L volumetric flask and top
up to 1L with deionized water. Put a lid on the 1L flask and invert 10 times.
This step results in a 1 in 200 dilution of the solution from step 1.
concentration of this solution is 500μg/L. This solution can now be used as Pt-2
calibration of the CPHYLL sensor.
The dilute solution can be stored in a dark bottle in a refrigerator for up to five
days. After that time it must be discarded.
© 2013 Palintest Ltd.
Part number: 70301027
Description: Rhodamine WT Liquid
Supplier: Keystone Europe Ltd.
Contact: http://www.dyes.com
www.palintest.com
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