35. Measure absorption of the samples at 880 nm with 2 cm
cuvette (if the absorbance is greater than 0.6, dilute the sample), and calculate the particulate organic phosphate concentration by the calibration curve (see Note 4).
4 Notes
1. It is critical to have proper training before running the analyzer.
This will depend on the system that you are using, and it is
beyond the scope of this chapter to go into the details of the
operation of the instrument. We have used Thermo Scientific
Aquakem 250 analyzer for phosphate.
2. Calibration curve is prepared by plotting measured absorbance
of standards versus standard concentrations (linear regression).
3. Start each sample run with blank(s) and reference material to
verify proper operation of the instrument. Analyze samples in
sequences of max 20 samples followed by a blank and reference
material. Insert also standards in the sequence to test accuracy
and drift during the analytical runs.
4. Determine concentration in the sample by the slope of the
calibration curve. Reduce the absorbance of the blank/reference
from the absorbance of the sample.
5. There should be a clear color on the filter, but not forming a
“cake” of biomass.
6. This is to minimize the water content as much as possible.
7. Make sure to loosely cover the scintillation vials, e.g., with
aluminum foil; once the filter is completely dry, close the cap.
The dried filter can be stored at room temperature.
8. Any marking will burn off, so they need to be placed in a way
that you can keep track of sample numbers; mark again after they
have cooled down.
References
1. Dyhrman ST (2016) Nutrients and their acquisition: phosphorus physiology in microalgae. In:
Borowitzka M, Beardall J (eds) The physiology
of microalgae. Springer International Publishing, NewYork
2. Hillebrand H, Steinert G, Boersma M et al
(2013) Goldman revisited: faster-growing phytoplankton has lower N:P and lower stoichiometric flexibility. Limnol Oceanogr 58:2076–2088
3. Grasshoff K, Ehrhardt M, Kremling K (1999)
Methods of seawater analysis. Wiley-VCH Verlag Gmbh, Weinheim
4. Koroleff F (1979) Methods for the chemical
analysis for seawater. Meri 7:1–60. (in Finnish)
5. Solo ´ rzano L, Sharp JH (1980) Determination of
total dissolved phosphorus and particulate phosphorus in natural waters. Limnol Oceanogr
25:754–758
94
Jaana Koistinen et al.
cuvette (if the absorbance is greater than 0.6, dilute the sample), and calculate the particulate organic phosphate concentration by the calibration curve (see Note 4).
4 Notes
1. It is critical to have proper training before running the analyzer.
This will depend on the system that you are using, and it is
beyond the scope of this chapter to go into the details of the
operation of the instrument. We have used Thermo Scientific
Aquakem 250 analyzer for phosphate.
2. Calibration curve is prepared by plotting measured absorbance
of standards versus standard concentrations (linear regression).
3. Start each sample run with blank(s) and reference material to
verify proper operation of the instrument. Analyze samples in
sequences of max 20 samples followed by a blank and reference
material. Insert also standards in the sequence to test accuracy
and drift during the analytical runs.
4. Determine concentration in the sample by the slope of the
calibration curve. Reduce the absorbance of the blank/reference
from the absorbance of the sample.
5. There should be a clear color on the filter, but not forming a
“cake” of biomass.
6. This is to minimize the water content as much as possible.
7. Make sure to loosely cover the scintillation vials, e.g., with
aluminum foil; once the filter is completely dry, close the cap.
The dried filter can be stored at room temperature.
8. Any marking will burn off, so they need to be placed in a way
that you can keep track of sample numbers; mark again after they
have cooled down.
References
1. Dyhrman ST (2016) Nutrients and their acquisition: phosphorus physiology in microalgae. In:
Borowitzka M, Beardall J (eds) The physiology
of microalgae. Springer International Publishing, NewYork
2. Hillebrand H, Steinert G, Boersma M et al
(2013) Goldman revisited: faster-growing phytoplankton has lower N:P and lower stoichiometric flexibility. Limnol Oceanogr 58:2076–2088
3. Grasshoff K, Ehrhardt M, Kremling K (1999)
Methods of seawater analysis. Wiley-VCH Verlag Gmbh, Weinheim
4. Koroleff F (1979) Methods for the chemical
analysis for seawater. Meri 7:1–60. (in Finnish)
5. Solo ´ rzano L, Sharp JH (1980) Determination of
total dissolved phosphorus and particulate phosphorus in natural waters. Limnol Oceanogr
25:754–758
94
Jaana Koistinen et al.