18
Filta-Max
xpress
Operator’s Guide
3. First aspiration:
a. Aspirate the supernatant immediately following centrifugation, leaving 25 mL of the
supernatant in the tube.
b. Once aspiration is complete, vortex the sample at full speed for 20 seconds to disperse
the pellet (extend vortexing time if needed).
c. Swirl and pour into a 50 mL centrifuge tube.
d. Add 10 mL reagent-grade water to the 500 mL centrifuge tube (this acts as a rinse).
e. Vortex the sample at full speed for 20 seconds.
f. Swirl and pour into the 50 mL centrifuge tube.
g. Add a second 10 mL reagent-grade water rinse to the 500 mL centrifuge tube.
h. Vortex the sample at full speed for 20 seconds.
i. Swirl and pour into the 50 mL centrifuge tube.
4. Second centrifugation:
Perform a second centrifugation of the 50 mL centrifuge tube containing your sample, using
the following centrifuge setup:
Centrifuge requirements
(e.g., Hettich Rotanta 460)
• Swing-out rotor
• Inserts and support cushions for 50 mL centrifuge tubes
• In good working order, with bucket supports lightly greased
Centrifuge setup
• Locate centrifuge to minimize vibration.
• Set RCF to 1500 × g.
• Set acceleration to maximum and deceleration to minimum, with the minimum amount of
braking possible
• Set time to 15 minutes, excluding ramp-up time.
5. Second aspiration of supernatant:
• Carefully remove the 50 mL tube from the centrifuge.
• Aspirate to the 3 mL mark on the 50 mL tube.
• Perform IMS on the sample as soon as possible.
To resuspend the pellets:
1. From the centrifuge tube, aspirate the sample supernatant leaving approximately 7–8 mL in
the tube.
Notes:
• Hold the pipette in the center of the tube, and aspirate the sample from the surface of the
liquid. Avoid disturbing the pellet.
• Use a wide bore pipette (such as a 5 mL serological pipette) or equivalent attached to a
vacuum source.
• Do not exceed a vacuum of -0.5 psig. The flow rate during this procedure should be
approximately 200 mL per minute (+/- 20 mL).
• IDEXX suggests using a peristaltic pump attached to a waste trap for this procedure.
2. Resuspend the pellet by vortexing the sample for 20 seconds; extend the vortex time if
required.
