Pipettors that are designed for use on 384-well microplates with a 16 x 24 format pose some challenges for pipet tip vendors. The problem is that if you line sixteen or twenty four standard pipet tips up in a row that the hub of the pipet tips, when added together will be too wide for the tips to go into the closely spaced wells of a 384-well plate. This problem is not encountered in the more common 96-well plate in the 8 x 12 format. Specifically, the tip spacing of a 384-well plate requires the tips to be 4.5 mm center to center. The diameter of most 10 microliter micro pipet tips is 6mm, even though the bore diameter is the same 3.3mm due to the flange. Since the maximum capacity of a standard depth 384-well plate is 100 microliters, the most common maximum volumes will be in the 10 – 50 microliter range.

Given the dimensions of a 384-well plate, the options for tips that fit pipettors designed for 384-well pipetting is to make a tip with a hub diameter that is no larger than approximately 4 mm. In order to load all 16, 24 or more channels at once, you must buy these tips in a rack that is laid out in the same format as the 384-well plate, 16 x 24. The rack needs to be very stable. An example of such a rack is shown in Figure 3.

Axygen Scientific, Capp, Rainin, Thermo Scientific Matrix and Thermo Scientific Labsystems Finnpipette are the companies we have identified as of the publication date who offer pipettors designed for use with 384-well plates. Of course, each of these companies offers tips that will work on their pipettors.

Perhaps because of the limited size of the market for 384-well plates, and perhaps because few people who do this type of work will risk trying tips not make by the pipettor manufacturer, the options are very limited. One of the few companies who make tips is Labcon, maker of VWR Private Label tips.

As of the publication date of this article, Thermo Matrix Scientific is in a backorder status for their pipet tips designed for the 16+ channel pipettors. Customers are looking for alternatives to fit their Matrix pipettors. Labcon makes five different tips, all 30µ capacity which they state will work on the Matrix 16+ channel pipettors. They are P/N 1016-800-300, 1016-960-306, 1016-965-306, 1150-965-306 and 1150-800-300. However, all of these except the 1150-800-300 which is packaged bulk come in 8 x 12 format racks. This requires double mounting 8 then 8.

Axygen is another manufacturer who makes tips for both 384 and 1536 format manual pipettors. They also make the Axypet-16 channel pipettors. Their tips come in two sizes, 30µL (T-1536-L-R, T-1536-L-R-S, T-1536-R and T-1536-R-S) and 60µL (e.g., T-384-R and T-384-L-R). Axygen’s tip fitting matrix states that these tips will work on Axygen and Capp pipettors. They also make a tip for the Finnpipette (FPT-384-R and FPT-384-R-S) in 50µL capacity.

Rainin has a number of pipettors with 16 and 24 channels. We contacted Rainin for their recommendation on tips an E24-20 model and were told that Rainin pipettors in the 16 and 24 variety take standard LTS tips. They recommended the RT-L10. We have carefully measured this tip in the hub diameter is 6mm. How a 24 channel pipettor with tips that are 6mm in diameter can fit into a 384-well pipet where the wells are spaced at 4mm is a mystery to us. So if this has been working for you, then stick with it. If you are daring, you might try some of the LTS compatible tips but do so at your own risk!

There is still work to be done to determine which aftermarket tips will work on 384/1536 format pipettors. Our stance at this point is to go strictly by the manufacturers recommendations. Until we can verify that an aftermarket tip has been verified to work on a given pipettor, we will avoid making a recommendation.