Since the patent for Gilson’s Pipetmen expired in 1991, there has been a steady parade of knockoffs available for purchase. Although the design of many is obviously taken directly from the Gilson line, there are a few exceptions. One is the mLine pipettor from Biohit Plc. (Helsinki, Finland). I recently had to replace a set of Pipetmen and was attracted to a special promotion offered by USA Scientific. In addition, the sales rep brought an mLine pipettor by the lab and I liked the look and feel of it.
One of the first things I noticed about the mLine pipettor is that it is remarkably light; the 20-200 ul model weighs only 77 g. The pipettors are available in the standard volumes of 10, 20, 100, 200, 1000, and 5000 ul for the single-channel and 10, 100, and 300 ul for the 8- and 12-channel models.
Another nice feature is the spring-loaded shaft that gives a little to indicate that sufficient pressure has been applied when loading a tip onto the pipettor. The volume adjustment has also been very well designed. For one thing, it is almost effortless to turn the adjustor knob. In fact, you can literally spin it, which makes large volume adjustments very easy. Since such an effortless volume adjustment mechanism would allow the setting to drift off the set value just as easily, the mLine volume setting has a locking feature. Volume adjustment is carried out while depressing a button on the side of the pipettor. After the correct volume is reached, the setting is locked in by releasing the button.
The mLine pipettors also come with a handful of small filters that fit into the tip of the pipettor for added protection of the shaft. Although the filters are a good idea in principle, they may be unnecessary since pipetting conditions that could contaminate the shaft are more easily handled with filter tips. In addition, the filter on the 20-200 ul pipettor I have actually pressed against the filter in the filter tip I was using, requiring that I remove the pipettor filter.
Each mLine pipettor also comes with 4 different colored rubber covers for the plunger button for easy identification of which one to grab for a given volume range. Importantly, the pipettors can be calibrated by the user. Each one comes with a small wrench that allows the aspirated volume, measured by weighing, to be tweaked to match the volume setting.
Overall, I’m very satisfied with the mLine pipettor. Some positives are the weight, the locking volume adjustment, the spring-loaded shaft, and the price. With the special promotion from USA Scientific, I bought four and paid just under $190 for each one. The promotion also included a free carousel and a boat load of pipet tips. An added plus is the fact that the pipettors can be sterilized by autoclaving. Although I can think of no big problems with the mLine pipettors, the 2-20 ul model I have doesn’t eject one type of tip I have been using. Although the pipettors are claimed to work with all universal tips, it could be that this brand doesn’t fit far enough onto the shaft to allow the ejector to work. The ejection function works fine with other tips. Finally, since I have had these pipettors only about a month, I can’t say anything about their durability. Since they come with a 3-year guarantee, this might not be a problem.
Michael Campa, Ph.D.
Assoc. Research Professor of Radiology
Duke University Medical Center