Does the water retained in a filter paper affect the chlorophylla measurement?

Abstract

The present study investigated the effects of water seeped in a filter paper on the variations of chlorophylla measurement. As little as 184 μl water retained in a 25 mm diameter GF/F filter paper after filtration resulted in the settlement of 60% chlorophylla at the bottom 20% of the extractant (90% acetone) in the extraction tube. More than one order difference in concentration of chlorophylla was found between the uppermost 20% and the bottom 20% of the extractant. Chlorophylla is trapped at the bottom by a pycnocline created by the water seeped into the filter paper and by chlorophylla itself, which is heavier than the extractant. Once the extractant was well mixed, good reproducibility of measurement was obtained. White precipitation occurred during the mixing of seawater sample and the extractant and was not found to affect the measurement of chlorophylla. The dilution of the extractant by the seawater seeped in the filter paper during extraction probably did not affect the extraction efficiency.