CELL   HARVESTING   SYSTEM   FAQ

Because of the durability of the Inotech harvester, little maintenance is required. Preventative measures are the key to maintaining reliable service from the Inotech Cell Harvester.

Why is aspiration slow and incomplete?

Reasons for slow or incomplete aspiration are 1) poor vacuum source, 2) leaking vacuum bottle and tubing, 3) leaking aspiration valves or 4) damaged/clogged dual tube system of the processing head.

  1. The vacuum source should be about 400 mmHg (16"Hg) with all valves closed. The amount of vacuum pressure needed depends on the composition of the samples harvested and the characteristics of the filter mat. The recovery time of a vacuum pump or in-house line is important; some will generate a strong initial vacuum but will not maintain a good working vacuum level once the aspiration valves are opened.
  2. Check the vacuum bottles and tubing. Check the bottle cap and make certain it's hand-tight. Make sure that the tubing attachments to the harvester valve block are secure. The ferrule should be over the tubing end and pushed against the inside of the fitting. Examine all the tubing on the harvester for fit and adjust if necessary. If tubing gets pushed or bent one of the fittings may pull apart and leak.
  3. Examine the aspiration valves. Depress each button several times to spring loose any blockage in the outlet tubing. If there is a problem within the valves, contact the Inotech office.
  4. Check the position of the processing head on the harvester; if it is mis-aligned that will prevent even aspiration of all the wells.

  • Each dual-flow tube on the processing head should have nylon tips in place. If one or more nylon tips are missing, it may cause uneven collection.
  • Check the O-rings for cracks or damage. All O-rings in any operating system will wear out and when stretched and compressed, they will eventually fail, and need to be replaced. The large O-ring that seals against the back of the cutting plate is usually the first O-ring to wear out because it receives the greatest amount of pressure during harvesting.
  • Remove the processing head from the harvester, and hold it up to the light to look for any blockage within the dual-flow tubes. Do not use a wire or poke down into the tubes; the inside of the tubes may become damaged. If clogged, force fluid through the tube(s) with a syringe, from the O-ring surface into the tube. If the material cannot be dislodged, soak the processing head overnight in standard laboratory glassware detergent solution or overnight in 10% formic acid. If individual dual-flow tubes are bent or misshapen, call Inotech for replacement or repair.
Why is the wash solution dispensing unevenly?

If gravity feed is the pressure source, then the uniform dispension of the wash solution will not exist unless the container of wash solution is more than three meters above the harvesting system. Gravity feed of the wash solution is not recommended because this technique does not guarantee the correct amount of pressure. An inexpensive wash pump and reservoir is available, please call Inotech at (800) 635-4070 for more information.

Uniform dispension of wash solution to all the wells or tubes requires sufficient pressure. If there is adequate pressure, but the dispension is not uniform, there may be precipitates or particles of debris trapped inside the processing head. Remove the processing head, soak it overnight in 10% formic acid and then rinse with distilled water. Make sure the formic acid gets inside the processing head. For a stronger cleaning solution, use the Inotech Cleaning Solution Kit (IHC-500). If the problem persists, call the Technical Services Department at Inotech. Do not take the processing head apart.

Why is the filter unevenly cut?

The end-user may have mis-alignment when one side of a filter disc is completely cut while a section of the filter disc is not, or, one area of the plate is completely cut but the remaining section of the plate is not. An asymmetrical pattern indicates that part of the disc-cutting surface is too low and it should be re-aligned. To re-align, place a very thin (0.5mm) spacer, on the side that is cutting completely, between the cutting plate and the processing head. Completely close the harvester, then open. This step should re-align the head, so check for evenness of the cut. If this does not solve the problem, call Inotech at (800) 635-4070.

Why is the wash solution dripping?

Dripping of wash solution during the initial harvesting process may be caused by air bubbles within the processing head. Press the wash solution (blue) button for approximately two seconds, two or three times consecutively, to remove the air from the wash line and the processing head.

Within the processing head of the harvester is an elaborate baffle system for dispensing the wash solution evenly to all wells of the microtiter plate. After harvesting, residual wash solution remains within the processing head by surface tension and any slight disturbance may break the seal and cause the contents of the baffle to drain. Residual wash solution will remain in the processing head (~10ml) after harvesting unless the processing head is removed and the solution is poured out. Removal of the processing head does not need to be done after each run, but the recommendation is to do this when the harvester is not to be used for a period of time.

To remove any residual wash solution, unlock the processing head, set a collection vessel up to the dual-flow tubes and gently pull the processing head forward. Any solution in the baffle will drain.

If you find wash solution dripping from the tubes of the processing head while the harvester is in use, it is possible the wash solution (blue) valve is leaking. To check this, remove the processing head to expose the wash solution entry port. The entry port is on the right side of the unit and is surrounded by an o-ring. Turn on the wash solution pump, but DO NOT press the blue button. If the valve is leaking, wash solution will flow through this port. The valve will need to be replaced.

Why are "craters" forming on the filter?

Crating of the harvested filter surface is a sign of too strong a vacuum. The sample moves through the aspiration tubes and strikes the filter with a high rate of speed.

One of the following should solve this problem:

  • If your vacuum pump has a valve for regulating the vacuum pressure, lower the vacuum level until the crating no longer occurs.
  • Manually bleed off vacuum with the harvester aspiration (red and green) valves. Prior to harvesting, depress either aspiration valve for about five seconds, or until you can hear the vacuum flow diminish. Then harvest.
  • Consider a Vacuum Controller (IH-195) if any of these methods fail to work.
Is it possible to harvest a partially filled microtiter plate?

Harvesting partial plates is possible. Keep in mind that the vacuum will follow the path of least resistance. With the Inotech harvesting system, all wells are aspirated simultaneously; empty wells will bleed off vacuum at the expense of the full wells. If the vacuum source is sufficient, all wells will be aspirated; however, some wells may take more time to empty. After the subsequent washing steps, all wells should show equal aspiration time.

To prevent aspiration delays:

  • Have liquid in all wells of the microtiter plate prior to harvesting. Whether it is media or water, having solution in each well will give uniform aspiration for all wells.
  • By quickly depressing the blue valve, wash solution may be added to each well prior to the initial aspiration. Care should be taken so as not to overflow the wells with harvesting material.
When the harvester is closed, the arm will spring up and re-open the harvester. What will prevent this?

A simple adjustment is needed. Open the harvester, remove the processing head and adjust the screw located on the interior side of the harvester. With a metric Allen wrench, slowly turn the screw counter-clockwise. This adjustment will prevent the harvester arm from springing up.

How are the Vacuum Bottle System (IH-193) and the Wash Pump with Reservoir (IH-186) set up?

Follow the diagram provided.

How is the VacuSafe System set up?

Follow the diagram provided.

Does the Harvester need to be decontaminated?

Contamination of the Inotech Harvester with radioactive materials is minimal. This contamination is confined to the grooves around the O-rings of the processing head and the nylon tips of the dual-flow tubes.

If you need to decontaminate the Inotech Harvester, the following solution is recommended:

100mL commercial decontaminant
50mL Triton detergent (X-100 or other)
20g EDTA
Bring solution to one Liter.

To decontaminate the Harvester, aspirate approximately 100mL of the solution through the Harvester and into the waste collection bottle. Allow the harvester to stand for a few minutes. Aspirate water through the system.

If the Harvester or processing head needs to be sent to the Inotech office for cleaning, it must be decontaminated before it is shipped. The Inotech office cannot accept any item contaminated with radioactivity.