Tangential flow filtration (TFF) concentration of phytoplankton
Get Vivaflow catridge out of storage Mount Vivaflow catridge as Fig.
1 (image de C. Brussaard) in open circuit.
Remove the clamps Set the pump to maximum speed.
Manometer should be at about 2.5 bars (with a new cassette sometimes the manometer get stuck, if the value is too low there is a leak in the system).
Rinse the cartridge with about 250 mL of MilliQ water (longer is cartridge has been stored in ethanol). 
Replace MilliQ water by sample in 6 L bottle. 
Take sample for flow cytometry to compute concentration factor.
Rinse cartridge with about 250 mL of sample. 
Put the retentate line into the sample bottle (Fig. 2B - Recirculation mode).
Record sample volume and start pump increasing to macimum speed.
Clamp the retentate line to increase filtrate flow so that Manometer gets up to 2.5 bars.
Concentrate sample until about 250 mL remains (6 L takes about one hour).
Transfer sample to a smaller bottle (250 mL) then finally to a 50 mL tube with conical bottom. 
Continue to concentrate very carefully, lowering the pump speed until the sample volume is reduced to 15-20 mL. 
When final volume is about 10 mL, clamp filtrate tube and recirculate slowly (no change of volume should take place). 
Leaving the filtrate tube clamped, get the feed line out of the sample in order to get back the total volume of concentrated sample. 
Take sample for flow cytometry count (to compare with original sample concnetration and estimate concentration factor). 
Store concentrated sample for later use (e.g. flow cytometry sorting, culture etc...). 
Go back to Fig. 1 configuration (Open circuit). 
Rinse 1 min with filtered sea water. 
Rinse 1 min with distilled water. 
Rinse with 50 mL NaOH 0.1 M. 
Put all three tubes (feed, retentate, filtrate) in bottle containing NaOH 0.1 M. 
Recirculate for 20 min (to get rid of everything on the cartridge filter). 
Rinse with 250 mL of MilliQ water (Fig. 1). 
Stop the pump and clamp all three tubes. 
Store at 4°C.
For a storage beyond 1 day, store with Ethanol 10%
