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Mini centrifuges

10 October 2019 Tags: centrifugation centrifuges spinning mini centrifuges

When I started my own lab I had just about enough money to buy a single ex-demo SCF2 Microcentrifugre from Stuart as the main microcentrifuge of the lab. One repeated task is the quick spinning down of samples after mixing, which does not require high power, and the SCF2 unit does this reasonably well, as it features a "short" button, which triggers spinning only as long as it is pressed. We did look into purchasing centrifugres with relatively low fixed speeds dedicated to the quick spinning down of samples, but given the relatively hefty price tag I was convinced we would never need them.

This changed when we were given a Stuart SCF1 as compensation for a particular piece of equipment that had repeadly broken down for a number of different reasons and had caused a considerable amount of grief. At the time Bibby Scientific was generous enough not only to fix the piece of equipment free of charge but also to give us the mini spinner as a sign of good will. But it indeed has turned into a constantly used piece of equipment, mainly due to convenience, and we have units from three different brands in the lab by now.

Stuart SCF1 Spinner minicentrifuge

The Stuart SCF1 remains my personal favourite. It does exactly what it has to do. With a speed of about 6000 rpm it it will get mini drops and droplets down even if not spinning at full speed. It comes with two inserts, one with 8 holes for conventional reaction tubes and a second one that will hold a single strip of 8 PCR tubes per side. It also comes with 8 adaptors for spinning of 0.5 ml reaction tubes. The clear blue plastic lid makes it easy to judge spinning speed. Spinning is triggered by closing the lid and spinning stops quickly once the lid is opened again. While not exactly cheap, it is cheerful and it does exactly what we need it to do in our lab environment.

SCF1 Spinner minicentrifuge produced by Stuart

SLS lab basics mini centrifuge

The lab basics mini centrifuge is very similar to the Stuart SCF1. It has a slightly higher spin speed (7000 rpm), which makes little difference and is no advantage in our lab. It also comes with a rotor with 8 holes for conventional 1.5 and 2 ml reaction tubes, adapters for the smaller 0.5 ml reaction and PCR tubes and a second rotor for 2 strips of 8 PCR tubes. It comes with a darker plastic lid. This makes it slightly harder to judge spinning speed when being in a hurry, but realistically it makes little difference. The mechanism works precisely as with the SCF1: closing the lid starts the spinning, and opening the lid stops it. It is a solid piece of equipment that we use every day in the lab.

SLS lab basics mini centrifuge , purchased via SLS.

IKA mini G

The mini G from IKA is more expensive than the lab basics mini centrifuge from SLS. It has one outstanding feature: it seems to be very solid. The footprint is slightly larger, it comes with dedicated buttons, and overall it behaves like a solid piece of kit. Spin speed is fixed at 6000 rpm and it comes with a 8-hole rotor for 1.5/2 ml reaction tubes and the usual set of adapters, as well as a second insert that holds two strips of 8 PCR tubes, which might be of interest to some users. In cotrast to the other two models the rotor does not simply click in place but is held by a dedicated screw. It looks good and feels solid – and for what we use it for it sits solidly between chairs. It simply does not work in the way we need it to work. It is so solidly built that it almost falls into the bracket of the more powerful SCF2 Microcentrifuge, but unfortunately it does not deliver in this category either.

For the work we do we need the centrifuge either to spin at high speeds to achieve high gs or we need it to be very fast to spin down drops after thawing of samples, mixing etc. The mini G does neither. Spin speed is restricted to 6000 rpm (~2000 g), so it certainly does not rival the SCF2. But it is not fast either. It actually comes with time settings that range from 1 to 99 minutes. The SCF1 we use for about 10 s and for our work we have never exceeded a minute. But the mini G does not even come with the "short" button that the larger SCF2 has. The sample needs to be placed in the rotor, the lid needs to be closed, then the "On" button needs to be pressed. The model claims to have a fast start-up speed, but in comparison to the SCF1 it is very slow. Once it has sped up the "Stop" button will stop it relatively slowly, but at least opening the lid will lead to a slightly quicker stop, as with the other models. This type of centrifugation has to be "quick and dirty" and both the SCF1 and lab basics mini both do this very well. The mini G is far too developed and I would not buy it again. I would rather stick the samples in the SCF2 and press the "Short" button. This is a shame, as I absolutely admire the way the mini G looks and feels, but it simply does not deliver in the way we need it to deliver.

IKA mini G, purchased directly via IKA.