YSI ADV6600 - Manual (Page 71)

Section 4. Calibration and Diagnostics
ADV6600
Y S I
Environmental
Page 61
4-6.11. Chlorophyll
To properly calibrate the YSI 6025 Chlorophyll sensor, calibration standards of known fluorescence
are required. Two general types of standards can be used:
• Phytoplankton suspensions of known chlorophyll content
• Dye solutions whose fluorescence can be correlated to that of chlorophyll.
The user is responsible for determining the chlorophyll content of phytoplankton suspensions, either
by employing the extractive analysis procedure described in Standard Methods for the Examination
of Water and Wastewater, or by analyzing the suspension in situ using a laboratory fluorometer.
YSI does not recommend the use of molecular chlorophyll standards. The standards are usually
only soluble in organic solvents such as acetone that would cause serious damage to the materials
used in the YSI 6025 probe. Damage caused by exposure to solvents or other solutions is not
covered under warranty. Even if molecular chlorophyll standards soluble in aqueous media were
available, their fluorescence is not likely to emulate in vivo chlorophyll fluorescence any better than
a dye solution.
CAUTION: For assured accuracy of field measurements made with the chlorophyll sensor, it must
either be initially calibrated using a phytoplankton suspension of known chlorophyll content, or
post-calibrated in a spreadsheet comparing the fluorescence values obtained in field studies with
laboratory analysis of grab samples collected during the field study. The use of a chemical dye
standard for “calibration” of the sensor is only an approximation and may not result in accurate
correlation between fluorescence and actual chlorophyll readings. Chemical dyes are designed
primarily to evaluate the sensor for drift. YSI does not provide an accuracy specification for
chlorophyll due to these limitations.
Preparation of Rhodamine WT Standard Solution
CAUTION: Be certain to read and follow all the safety instructions and MSDS documentation
which is supplied with the dye before proceeding. Remember that only trained personnel should
handle chemicals.
Rhodamine WT dye is usually purchased in solution form and can vary somewhat in nominal
concentration. YSI uses Rhodamine WT from the supplier noted below and recommends that the user
purchase this exact item if possible. The solution is approximately 2.0 % in Rhodamine WT.
Fluorescent FWT Red Dye (Item# 106023; 16 Fl. Oz.)
Kingscote Chemicals
3334 South Tech Blvd.
Miamisburg, OH 45342
Ph. 1-800-394-0678