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What factors should be considered when choosing a syringe pump?

What is your application?
How many syringes will be used simultaneously?
What size syringe will be used?
What flow rate(s) will be used?
What is the total volume to be delivered?
Does the pump need to withdraw (fill the syringe) as well as infuse (dispense)?
What is the viscosity of the liquid you are pumping?
What are the pressure requirements of your experiment?
Does the pump need to continuously infuse over a 24-hour period of time?
Does the pump need to be programmable?
Does the pump need to be controlled with a computer?
Does the pump need to have TTL capabilities (ex. external control of valves, use of footswitch, etc)?
Please contact Technical Support at for help selecting a pump that meets your needs.

Harvard Apparatus syringe pump is hooked up to a computer and is not responding consistently or well to commands through LabView. How can this problem be corrected?

If you are using LabVIEW with your ULTRA or Elite syringe pump, we recommend starting each experiment by setting the command NVRAM to off. This command prevents the pump from storing commands sent to it by LabVIEW and prevents read/write errors by the pump. If you are having an issue you may see that the command set has switched from CMD ULTRA to CMD 22 or change from displaying a PHD ULTRA I/W to a PHD ULTRA I Only. (Parts: 70-3XXX / 70-45XX)

How to resolve communication/response issues:
a. Communication issues with Harvard Apparatus CP Pump during PID method.
b. Communication issues with PID Software.
c. CP pump ceases to respond to any external device.

If your Harvard Apparatus CP Pump is operating normally from the touchscreen, the PC can recognize your pump, but Pump Terminal (included with user manual CD) and/or PID Data Logger software (version 1.0.1) is not receiving all data during a connection attempt please follow the following instructions:

1. Install TeraTerm.
You can download TeraTerm from the above link; we recommend selecting the teraterm-4.92.exe file rather than the zip so that you don’t have to bother with unpacking it and can just install directly. This is a terminal program similar to Pump Terminal, but with the crucial capability that it forces the connection.

2. Connect the pump to the USB port.

3. Connect to pump via TeraTerm.
When you open TeraTerm it will launch to a TeraTerm: New Connection window set by default to TCP/IP. You will want to change the selection to Serial, and then select the pump from the drop-down menu and hit Ok. This will take you to the Tera Term main window, which is black with a flashing white position marker.

4. Type "cmd ultra" (without quotes) and hit Enter. You will not be able to see what you typed but once you have hit Enter, proceed to the next step.

5. Type "poll off" (without quotes) and hit Enter. You will not be able to see what you are typing, but once you have hit Enter a “:” should appear. This means the fix was a success.

6. Close Tera Term, Open Pump Terminal, and attempt to connect to the pump. If the fix was a success the pump will connect successfully.
Now you should be able to close Pump Terminal, launch the PID software, and connect successfully.
(Parts #: 88-3015 / 88-3016)

My Harvard Apparatus Nanomite Elite syringe pump stalls frequently. Why?

While there are many reasons for syringe pumps to stall we recommend that the Harvard Apparatus Nanomite be operated at 100% force. If the problem persists please contact Technical Support. (Part #: 70-4507)

My Harvard Apparatus Pump 22 gets hot to the touch. Is this normal?

The Model 22 will get a hot spot on the right side of the keypad. This is normal as there are three heat generating components mounted just below the keypad. The pump's function is not affected by the heat, but the contents in your syringes may warm. (Part #: 55-22XX)

Fluid continues to flow after I stop my syringe pump. Is there an issue?

Many aspects of an experimenter's set-up may cause this to happen. Using plastic syringes can cause an imprecise onset and offset of your fluid flow. If you are working with very small or restricted fluid pathways you can experience a build-up of pressure and the flow can continue after the pump has stopped. The viscosity of your fluid can also cause pressure build-up and result in a continued flow past the offset of your pump.

What is the flow rate for the Pump 11 syringe pump?

The flow rate is from 0.0014 µl/hr to 26.56 ml/min.

Don't see your answer? Please submit a question!

We welcome your questions! Email a question to us and we'll answer you directly. We'll also anonymously post your question to our FAQ Knowledge Base to assist other people.

Harvard Apparatus Peristaltic Pump shows clean and lubrication error message. What do I do?

Customers cannot clean and calibrate Harvard Apparatus' peristaltic pumps. This error message can be cleared by resetting the pump's 100-hour clock on the settings menu. (Part #: 70-7000 / 70-7001 / 70-7002)

What size tubing should I choose for my peristaltic pump?

Each type of tubing will have a minimum and a maxumum flow rate listed. For best performance, your desired flow rate should be 50&en;70% of the maximum flow rate. If the flow rate is below 20% of maximum, the output will be more pulsatile.

Don't see your answer? Please submit a question!

We welcome your questions! Email a question to us and we'll answer you directly. We'll also anonymously post your question to our FAQ Knowledge Base to assist other people.

What is the threading is used for the female side of the tip of the 200 ml stainless steel syringe?

The stainless steel tip thread is a 3/8-24 UNF-3A and approximately 3/8" deep. (Part #: 70-2263)

What syringe should I chose for my syringe pump?

Glass Gastight syringes are much more accurate than plastic syringes. Generally the error introduced by a glass Gastight syringe is 1% and the error introduced by a plastic syringe is 5%. Our pumps calculate flow rates based on the ID of the syringe and we recommend that when calibrating your set-up you create a custom syringe (ULTRA and Elite pumps) or change the ID by a few mm (larger or smaller) to increase your accuracy. If a syringe is chosen that has a volume much greater than the target volume or if you are targeting a very slow flow rate, the accuracy will be affected.

Don't see your answer? Please submit a question!

We welcome your questions! Email a question to us and we'll answer you directly. We'll also anonymously post your question to our FAQ Knowledge Base to assist other people.

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What is recovery?

The recovery of a particular substance is defined as the concentration in the dialysate expressed as percent of the concentration in the interstitial fluid. Relative recovery will approach 100% as the flow rate approches zero, and decrease as the flow rate increases. It is commonly expressed in percent. Absolute recovery is defined as the mass of a substance recovered during a defined time period. It is zero when the flow rate is zero, and will reach a maximum at higher flow rates.

What factors affect absolute recovery?

The absolute recovery (mol/time unit) of a substance from the tissue depends on (1) the “cut off” of the dialysis membrane (usually defined as the molecular weight in Daltons at which 80% of the molecules are prevented from passing the membrane), (2) the length and diameter of the membrane, (3) the flow rate of the perfusion fluid and (4) the diffusion coefficient of the compound through the extracellular fluid. Other factors such as pH of the medium and degradation of the substance may also affect the recovery. The reverse holds true for substances entering the tissue from the probe.

What is relative recovery?

The relationship between dialysate and tissue (or solution) concentration is termed relative recovery and is defined as the dialysate/interstitial concentration ratio expressed as a percentage:
Relative recovery= Cmd/Cint=1-exp-K0 A/F
where Cmd and Cint are respectively the concentration of your analythe in the microdialysate and interstitial (tissue or solution), K0 is the average mass transfer, A is the membrane surface and F the dialysate flow rate. Increasing the membrane surface or decreasing the flow rate will give a higher relative recovery. Also the membrane pore sizes will affect recovery. However, since full equilibration does not occur across the microdialysis membrane, the concentration of the measured substances in the dialysate is never equal to the true interstitial concentration.

How do the membrane length and flow rate affect recovery?

A longer membrane and a lower flow rate will give a higher recovery.

Why is my analyte concentration so low in the dialylsate?

The concentration will never be similar to what you see in your media. Unless there is total equilibration between your media and the perfusate, the concentration of a given substance in the dialysate will be lower than its actual concentration in your solution. This applies whether you are performing the technique in vivo or in a tissue.

How should the perfusion fluid be composed?

Ideally the composition of the perfusion fluid should be as close as possible to the composition of the extracellular fluid. However, you may want to change the concentration of sodium, potassium or calcium in order to influence the membrane function in the region you are studying. CMA offers Perfusion Fluid T1 for peripheral tissue and Perfusion Fluid CNS for brain tissue.

What is the pH of the CNS perfusion fluid?

The CNS perfusion fluid is intentionally not buffered in order to allow it to take on the same pH as the brain’s interstitial fluid. The pH of a non-buffered solution varies between 5 and 8.

How does the pH of the CNS perfusion fluid impact the tissue?

Since our perfusion fluid is unbuffered it hardly impacts the pH in the tissue. The perfusate will take on the same pH as the surrounding tissue. But the buffered substances in the tissue can have different recovery over the membrane which indirectly can have a small effect on the pH of the tissue.

What perfusion flow rate should be used?

Use a high flow rate if you want to remove or introduce as many molecules as possible per time unit. Use a low flow rate when you want to obtain a more concentrated dialysate (high recovery). Note that a low flow rate gives smaller volume. Consider also the volume needed for the analysis.

What time is needed to obtain steady state conditions?

The introduction of a probe into the tissue will always cause damage and the recovery of function will some time. An hour is often used to reach "baseline conditions".

When using a probe membrane with a cut-off of 20,000 Daltons, why isn't the recovery for molecules with 20,000 Da molecular weight 100%?

The ability of molecules to pass the membrane decreases logarithmically with the increase in molecular weight. By experience we know that most substances with a molecular weight up to 5,000 Da can be dialyzed when using a 20,000 Da membrane. This is of course very dependent on the substance and the sensitivity of the analytical method.

What causes faulty flow?

You may not have calibrated the pump to the syringe you are using. The syringe might be leaking or you are not using the syringe recommended by CMA.

What causes faulty volume of the microdialysis sample?

The probe may be leaking, the tubing may be blocked, something may be wrong with the pump, or the tubing adapters may be leaking.

Don't see your answer? Please submit a question!

We welcome your questions! Email a question to us and we'll answer you directly. We'll also anonymously post your question to our FAQ Knowledge Base to assist other people.

Which length of microdialysis probe membrane should I use?

A longer membrane gives a better recovery of the substances you are interested in but the choice is usually limited by the size of the molecule you want to study. CMA offers a variety of probes with different membrane lengths from 1 mm to 10 mm suitable for most experiments.

How do I choose the best membrane material for my study?

Different membrane materials have different molecular weight cut-offs (MWCO). A membrane with a low molecular weight cut-off purifies your sample by excluding large molecules. A membrane with high cut-off recovers large substances such as peptides or smaller proteins. Some substances can also bind to the membrane material. To optimize your choice you should conduct an in vitro test with the substance you want to monitor. CMA offers membranes made of polyarylethersulfone (PAES), 20,000 Daltons MWCO, cuprophane, 6,000 Daltons MWCO and polyetersulfone (PES), 100,000 Daltons MWCO.

How do I choose the right microdialysis probe for my experiment?

There are many considerations; however, a stiff probe is suitable for a stereotaxic experiment on the brain while a flexible probe may be suited for microdialysis in a peripheral organ such as adipose tissue, muscle, liver or kidney. CMA probe types are optimized for various uses:

  · CMA 12—optimized probe for CNS use, ideal for chronic implantation
  · CMA 11—a thin stiff probe for discrete brain regions
  · CMA 7—an extremely small stiff probe for CNS studies in smaller animals such as mice
  · CMA 20—a soft non-metallic probe for peripheral tissues and blood vessels
  · CMA 30—a linear probe suitable for skin and other peripheral tissues
  · CMA 31—a linear probe suitable for skin and other peripheral tissues with 55 kDa cut-off

Please use our Probe Selection Guide or contact Technical Support for more help.

Are CMA probes reusable?

The preclinical probes can be used repeatedly if rinsed and stored in deionized water between experiments. However CMA can only guarantee single usage.

When are probe guides needed?

Probe guides are used when performing microdialysis in the brain of a freely moving animal.

How do I prepare and clean FEP Tubing ?

When using FEP tubing, cut the tubing with a sharp scalpel or similar to be sure the ends are open. After use, rinse it with deionized water to wash out the salts.

How do I prepare Tubing Adapters for use?

Tubing Adapters can be swelled in 70% ethanol for easy connections with tubing and syringes. They will shrink back in air again and ensure tight fit and zero internal volumes.

What is the difference between the CMA 4004 pump and the CMA 402 pump?

CMA 4004 has a pulse free flow from 0.54 pl/min - 11.70 ml/min and runs four syringes simultaneously. The pump is calibrated for various sizes of syringes. Apart from microdialysis experiments, it can be used for microinjections of preset volumes that can be repeated in intervals. CMA 402 has flow rates between 0. 1µl/min - 20 µl/min, and is run by two syringes individually (1, 2.5 or 5 ml). Start/stop and flow rate can be set independently for each syringe. Both pumps can be used for infusion and withdraw.

What is the difference between the CMA 142 and CMA 470 Fraction Collectors?

The CMA 142 collects 20 fractions from 1 probe or 10 fractions from 2 probes. Fraction volumes from can be 1 µL - 50 µL in open vials. CMA 470 is a refrigerated fraction collector. It can collect 64 fractions from 1 up to 4 probes simultaneously (16 fractions/probe = 64 total). Fraction volumes can be from 1 µL - 2000 µL. Both opened and sealed vials can be used.

What is the use of a CMA 120 System for Freely Moving Animals?

This system enables Microdialysis studies on conscious, small laboratory animals over a long period of time. It can be used in combination with any one of CMA’s instruments.

What are the dimensions of the bowls for the CMA 120 System?

The CMA 120 Bowl with Food and Water Containers (8309672) and CMA 120 Plastic Bowl (8309031) are 360 mm high and 400 mm in diameter.


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