Retention of particulate adenosine triphosphate from Mediterranean deep-sea water by glass-fibre and membrane filters

When deep-water samples from the Mediterranean Sea were passed through glass-fibre filters (Whatman GF/F), the adenosine nucleotide concentration of the particulate material was exceptionally low. The concentration was higher when the particulate material was concentrated on SM cellulose-membrane filters with porosities of less than 1 mu m. There would seem to be two reasons for this: (1) inhibition of the bioluminescent reaction; (2) an apparently lower retention of ATP by the glass-fibre filters. In order to compare results obtained with the two different types of filters, a correction factor of two can be used if measurements are made with an internal standard. This constant factor can only be applied to samples from depths greater than 300 m.