Cruise Protocol for Filtering Nutrient Samples
*Pre-label the approximate number of bottles needed prior to each cast. Use C for cast
number, and N for Niskin number. (Example= Cast 54, Niskin 11; label would be C54
N11) Label the bottle on the cap and on the side of the bottle. Please make sure to use
permanent marker!
*Match Niskin number to sample bottle.
*Fill the syringe with approximately 10mls of water and partially insert plunger. Shake
vigorously so that the water cleanses the inside of the syringe. Afterwards, discard the
water. Repeat three times.
*Fill the syringe as full as possible and insert the plunger. Invert the syringe and try to
remove any bubble in the syringe. Attach the Sterivex (.22m) filter to the B-D 60 ml
LUER-LOKTM syringe. Advance the plunger and force 60mls of water through the filter.
This should be enough water to clean the filter of any previous sample. It should be done
each time a new sample is introduced to the syringe (filters should be used until it
becomes difficult to force water through them).
*Refill the syringe. After cleaning the filter, the bottle needs to be rinsed 3 times. Force
5mls of water into the bottle, replace the cap and shake vigorously. This step should be
repeated 3 times.
*Filter the sample directly into the nutrient vial and replace the cap and proceed to the
next sample. Please make sure that each sample is filtered using the same protocol.
*After each station, put bottles in the deep freeze and keep samples frozen (at all costs!)
until analysis.