Chlorophyll a is analysed directly from the filter papers from the NDS trays using the method
described in Section 7.3, but with slight variations. These are as follows:
• 60 ml containers are used for extraction of the chlorophyll because the NDS filter
papers are so large.
• The 60 ml containers do not fit in standard tube racks so need to be placed in the water
bath on a tray, while being held down with another tray on their lids.
• After boiling and leaving for 12 hours in the refrigerator, the containers with extractant
are shaken and a 5 ml aliquot is removed which is then placed in a centrifuge tube for
the balance of the analysis as described in Section 7.3.
• Blending is not required.
• Calculate chlorophyll a per square