Xylem EXO Series User Manual page 75

chlorophyll content of grab-samples taken during a deployment has been analyzed in a laboratory. This
determination can involve conducting the extractive analysis procedure described for chlorophyll in Methods
for the Examination of Water and Wastewater or by carrying out an in situ measurement of chlorophyll using
a commercial benchtop fluorometer.
Pour the correct amount of clear deionized or distilled water into the calibration cup. Immerse the probe
end of the sonde in the water.
In the Calibrate menu, select BGA-PC/Chlor, then select Chl RFU. Select either a 1- or 2-point calibration.
Enter 0 for first standard value and 16.4 for second standard value.
Click Start Calibration. Observe the readings under Current and Pending data points. While stabilizing,
click the Wipe Sensors button to activate the wiper to remove any bubbles. When data are Stable (or data
shows no significant change for approximately 40 seconds), click Apply to accept this calibration point.
Next place the sensors in the Rhodamine WT standard. Click Proceed on the pop-up window. Observe
the readings under Current and Pending data points. While stabilizing, click the Wipe Sensors button to
activate the wiper to remove any bubbles. When data are Stable (or data shows no significant change for
approximately 40 seconds), click Apply to accept this calibration point.
Click Complete. View the Calibration Summary screen and QC score. Click Exit to return to the sensor
calibration menu, and then the back arrows to return to main Calibrate menu.
Rinse the sonde in tap or purified water and dry the sonde.
Blue-green Algae
This procedure calibrates BGA RFU or BGA μg/L. If the user has both units selected, then this procedure
must be performed twice, once for each unit, to completely calibrate the parameter.
For the 2-point calibration, one of the standards must be clear water (0 μg/L), and this standard must
be calibrated first. The other standard should be in the range of the suspected BGA-PC content at the
environmental site. Two general types of standards can be used: (a) phytoplankton suspensions of known
BGA-PC content, and (b) dye solutions whose fluorescence can be correlated to that of BGA-PC. The user
is responsible for determining the BGA-PC content of algal suspensions by using standard cell counting
techniques.
For option (b), we recommend using a 625 μg/L Rhodamine WT dye solution (for detailed instructions, see
section 5.10), and the solution is used in the calibration steps below.
µg/L – 1- or 2-point
This procedure will zero your fluorescence sensor and use the default sensitivity for calculation of
phycocyanin-containing BGA in μg/L, allowing quick and easy fluorescence measurements that are only
semi-quantitative with regard to BGA-PC. However, the readings will reflect changes in BGA-PC from site
to site, or over time at a single site.
Pour the correct amount of clear deionized or distilled water into the calibration cup. Immerse the probe
end of the sonde in the water.
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