YSI ADV6600 - Manual (Page 72)

Section 4. Calibration and Diagnostics
ADV6600
Y S I
Environmental
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1. Accurately transfer 5.0 g of the Rhodamine WT solution into a 1000 mL volumetric flask.
2. Fill the flask to the volumetric mark with deionized or distilled water and mix well to produce a
solution that is approximately 100 mg/L of Rhodamine WT. Transfer this standard to a glass
bottle and retain it for future use.
3. Accurately transfer 5.0 mL of the solution prepared in the above step to a 1000 mL volumetric
flask.
4. Fill the flask to the volumetric mark with deionized or distilled water. Mix well to obtain a
solution, which is 0.5 mg/L in water (a 200:1dilution of the concentrated solution).
5. Store the concentrated standard solution produced above in a glass bottle in a refrigerator to retard
decomposition. The dilute standard prepared in the previous step should be used within 24 hours
of its preparation.
When rhodamine standards are required in the future, perform another dilution of the concentrated
rhodamine solution after warming it to ambient temperature. Our experience has indicated that the
concentrated solution that has been kept at cold temperatures is much more stable than the dilute
solution stored at room temperature.
It is well known that the intensity of the fluorescence of many dyes shows an inverse relationship
with temperature. This effect must also be accounted for when “calibrating” the YSI chlorophyll
sensor with rhodamine WT. Enter the calibration value from the table below corresponding to the
temperature of the standard. The table shows the approximate algal chlorophyll equivalent of 0.5
mg/L Rhodamine WT as a function of temperature.
°C µg/L Chl to Enter °C µg/L Chl to Enter
30 100 18 122
28 103 16 126
26 106 14 131
24 110 12 136
22 113 10 140
20 118 8 144
Calibration
When selecting to calibrate Chlorophyll, there will be a choice of zeroing the full-scale range of the
fluorescence sensor (Fluor Zero), or calibrating with actual chlorophyll standards (µg/L 1-point, 2-
point, or 3-point). A zero calibration should always be performed before each use of the YSI 6025
sensor. Multi-point calibrations will be required infrequently. In general, it is best to perform