YSI ADV6600 - Manual (Page 188)

Appendix E. Chlorophyll Measurements
ADV6600
Y S I Environmental
Page 178
It is important for the user to remember that, because of the limitations defined in this
appendix and in the Principles of Operation, YSI is unable to quote an accuracy
specification for the in vivo measurement of chlorophyll.
If the sensor is post-calibrated using the values from laboratory analysis of grab samples, will
my field data be totally accurate?
No, they will only be as accurate as possible within the limitations of the fluorometry
method. The limitations for all in vivo chlorophyll determinations will almost certainly
compromise the accuracy of your data even if you employ the best calibration method
possible. For example, different phytoplankton species are likely to fluoresce differently in
vivo even if the actual chlorophyll content is the same. Thus, unless the biological species
are perfectly homogeneous with regard to site in a sampling study and with regard to time
in a monitoring study, inaccuracy will occur if only a single phytoplankton calibration is
performed. In addition, the fluorescence intensity of many phytoplankton types shows a
diurnal cycle even though the same amount of material is present. Under this limitation,
the time of day at which calibration samples are taken would have to be identical to the