The Basics of Centrifugation

Posted on Nov 21, 2011 by Kelly Gleason in Lab Skills, Research

A quick guide on the basics of centrifugation

What to do for before using a centrifuge?

Ensure that the rotor is free of spillage and damage.
Look to see if the adaptors are the correct size for your blood tubes.
Always run a centrifuge with the full complements of buckets.
Balance your samples and distribute them evenly or diametrically around the rotor.
Tighten the lids securely on all buckets.Once you have set the centrifuge to the required centrifugation speed, time and temperature, stay with the centrifuge until it gets up to this set centrifugation speed. This is when things often go wrong. If the blood tubes are not properly balanced or there is a problem with a bucket or the rotor, the centrifuge will make an unusual noise and shake (a little like when a washing machine screeches and shakes when the clothes are not evenly distributed in the drum). Smaller centrifuges can shake and eventually come right off the bench. By staying with the centrifuge while it reaches the set speed, you reduce the risk of this happening as it is usually during the first few minutes that problems arise if they are going to at all. If a problem does occur, simply stop the centrifuge, open the lid and assess what caused the imbalance, correct the problem and start again.

Unbalanced centrifuge, one red tube must be moved to the opposite side of the small blue tube to ensure balance.

When placing the samples in the centrifuge you want to make sure they are evenly distributed. If your centrifuge has a circular ring, you place the samples at even intervals around the centrifuge ring. If your centrifuge is as above, you place the samples of the same size evenly across from each other. You do not have to use all four buckets, if your samples fit in two buckets that is absolutely fine as long as the number and size of samples in each bucket are equal. You can fill blood bottles with water help you to balance your samples if you have a odd number to samples to spin.

Balanced centrifuge using 4 buckets

What to do if a sample breaks in the centrifuge causing a spillage?

If when you open the centrifuge you notice that a sample has broken, close the lid immediately and leave the centrifuge closed for at least 30 minutes (1 hour is preferable). This allows aerosols to settle and lowers your risk of inhaling any harmful aerosols released from the broken samples. Once the 30-60 minutes has passed, open the lid and remove the bucket containing the broken tube and remove the lid from the bucket. You can remove the broken tube with the help of forceps if necessary. Broken tubes, even plastic ones, can be sharp so you want to avoid cutting yourself as gloves are often not very thick. You can then soak the bucket in the disinfectant used in your lab. You want to fill a bucket or bowl (the bottom part of a new sharps container works well for this if you have nothing else) with sufficient disinfectant to immerse the bucket in the disinfectant. Leave the bucket soak in the disinfectant for 5-10 minutes; the disinfectant will penetrate better if the water is a warm. You can then rinse the bucket and leave it to dry. You should also wipe the centrifuge surfaces clean of any spillage using disinfectant. Leave the lid open after leaning to allow the centrifuge to dry out well.

Unbalanced centrifuge with lids on

How to leave a centrifuge after use?

Make sure centrifuge is clean and dry.
Remove any spare adapters from the rotor.
Switch the power off.
Leave the lid open as condensation build up will damage the motor and the buckets

How to maintain a centrifuge?

Roger White, Operations Manager in Cancer & Surgery at Imperial shares a few useful tips to help you maintain your centrifuge:

Clean and lubricate rotor pins monthly.
High strength aluminium corrodes easily, to prevent this, remove adaptors and keep buckets clean and dry at all times.
Only clean aluminium buckets in a neutral ph cleaner. Do not use strong alkalis, acids or chloros.
Leave the centrifuge lid open overnight with the power switched off to prevent condensation build up which damages the motor and buckets.
Clean your centrifuge regularly, frequency of cleaning will depend on how often the centrifuge is used. To clean, remover all adapters and buckets. Wash all parts in warm water and a mild detergent. Do not scratch the protective anodised surface of the buckets. Allow to dry completely before reassembling to prevent corrosion. Never leave buckets soaking in cleaning or disinfectant products overnight as the most common cause of corrosion is liquid/sample caught between an adaptor and bucket or overnight soaking in cleaning products.

You will likely need to keep a maintenance record for all equipment you use to process samples for clinical trials. If you do not have a maintenance record for your centrifuge, medical engineering at your Trust or College will often offer a yearly maintenance check which you can keep on file to demonstrate show companies, auditors, inspectors that your equipment is being adequately maintained.

The Basics of Centrifugation