May 21, 2013
Most labs have used floor mount or bench top centrifuges for separation based assays for decades. Whether spinning samples to remove air bubbles, spinning down cellular debris or isolating supernatent, there are numerous manual access centrifuges on the market, but when it comes to automation, the choices are limited.
For a number of years, Agilent (formerly Velocity11) has offered the compact VSpin. VSpin has a two position rotor with buckets for std microplates. It can spin up to 300o rpm/ 1000g and has an automated door that allows direct access to plates using an offset robot gripper. Units can be stacked on top of each other for increased use of vertical workspace. The Optional Access2 loader can also grab the plate and present it externally to a liquid handler gripper or top loading plate mover like Twister2 or KiNEDx.
Hettich also provides a larger unit called the Rotanta 460 which can accommodate 4 plates at speeds up to 6200prm, but is a bit more of a challenge to integrate as the robot gripper fingers need to reach into the unit from the top. I have seen this done with Mitsubishi and Staubli robots and Tecan actually integrates this unit under an EVO liquid handler accessible via an open locator in the deck.
Sias’s Ixion is a compact unit, similar in size to the VSpin, however plate access (total of two) is through the top just like the Rotanta and can spin up to 2000rpm. This unit integrates nicely with Sias’ Xantus liquid handlers.
Finally, BioNex offers the HiG centrifuge which can also spin two plates. The bright orange color makes this unit hard to ignore…and a closer look shows that this unit may be the best of the bunch. With an automated lid that retracts from the top, the HiG does not need a plate loader like the VSpin as plates can be accessed by just about any robot gripper. At 5000g, BioNex claims this unit to be the fastest robot accessible centrifuge available.
Maintenance requirements for each of these devices is similar. All include high-speed motors so proper ventilation is a must. Bearings must be greased, sensors cleaned and pneumatics (door opening, plate loaders) checked for leaks. Additionally, rotors and buckets should be checked for cracks or other signs of wear. As noted in previous blogs, rotational speeds can be verified using a digital tachometer but you may need to remove covers to gain access to the rotor (kids, don’t try this at home…call a professional). As always, if you ignore that last piece of advice, don’t come crying to me when your friends make fun of you because you have a mircrotitre plate permanently embedded in your cheek…
February 6, 2013
For all you self-maintainers out there, some great reference sites;
- Lab Wrench – a great Q & A site where folks can post questions and get the community of users, maintainers and current/former field service techs. Not always the fastest way to get answers, but if your needs are not immediate well worth a try.
- LRIG Forum – The place to reach out to those in the know in the area lab automation. Expect some commercial pitches from vendors from time to time but by and large the people who subscribe to this message board are really interested in helping each other out. You will get lots of great guidance on how to make instruments interact (integrate), and a fair amount of troubleshooting expertise.
- LabX – Not really an interactive forum but you will find a number of companies that may be selling a product similar to yours. Often these folks wind up servicing/refurbishing used products prior to listing them here and may be able to help you out. If nothing else, it gives you an option for replacing your troubled instrument if you cannot repair it (use your device as a parts donor).
- Google – Seriously, did I really have to include a hot link to Google? If you needed that, please put down any sharp tools and step away from the lab… Believe it or not, Google can lead you to a number of academic research sites that store copies of user manuals, many of which include basic troubleshooting or replacement part numbers.
And of course, you can always contact us at info@TheLabSquad.com
February 4, 2013
Although the patent for PCR expired back in 2006 and promised to herald in a new wave of low-cost thermal cyclers, the legal debate over Taq polymerase enzymes continues to make some manufactures nervous about the North American market. Still, the number of new thermal cyclers to hit the market over the last several years has increased dramatically. As the prices for these work horse devices drops accordingly, the justification for service contracts starts to wane. When opting for a low-cost unit with no local service support, some users may be okay with depot repair or flat-out replacement. When opting for higher quality units, many labs are going with periodic maintenance and routine performance rectification (OQ/PQ). Printed reports or recalibrations by the service tech can be incorporated into your lab’s SOP’s but if you are self maintaining, don’t forget to have the data signed off by more than one person, especially if you are doing forensic or clinical work.
Now, let me put my spin on centrifuge support (wouldn’t be a blog without the occasional pun, now would it?). Seriously, it doesn’t matter whether you have a floor mount, bench top or robot-loaded centrifuge, these devices get a lot of use and it is not uncommon to see units that ten or more years old. Motors and bearings don’t last forever so routine maintenance is critical. Additionally, you folks that leave your rotors in the centrifuge and never take them out should have big scarlet letters painted on your lab coats so you can be publicly ridiculed by the service community! Seriously, many a lab tech has pulled a muscle or two trying to loosen and remove a rotor that has permanently bonded with the spindle.
Last on the docket for this posting is microplate reader upkeep and maintenance. Truly, a wide-ranging topic (may have to post separately on this one to do it justice). The three main readers types (modes) are absorbance, fluorescence and luminescence and while some are limited to one mode, others can do more than one (multimode). Of course there are also fluorescence polarization (FP), time resolved fluorescence (HTRF), high content imagers and microfludic analyzers, but for today we will stick with the big three. All three types work on the basic principle of light measurement to detect samples within the wells of a plate. Absorbance readers use a light source, filters and a detector to measure what percentage of the source light is transmitted through the sample. Fluorescence readers are more sensitive and measure the amount of light emitted from the sample, while Luminescent readers have no light source and instead detect a chemical or biological reaction from the sample. Depending upon the specific reader, any number of factors can result in bad data but generally most failures are a combination of optical alignments (emitter, detector, filters…etc) or light source age. Just about every plate manufacturer provides N.I.S.T. traceable “test plates” that can be used to calibrate the device and a number of third-party companies also have more generic standards that can also be used. It seems patently obvious to say, but what is the point of conducting an assay if you cannot say with a high degree of certainty that your detection results are accurate? At a minimum, plate readers should be PM’d once per calendar year and that procedure should include a test report against a known standard. If your lab only has one reader and it is critical to your research, an annual service contract that includes analytical data would be a wise choice.