Moving a whole plate at once and what that commits you to: why a 96 channel pipette transfers a plate in one action and why head geometry, tip cost and plate flatness then dominate everything, where multiple channel pipettes, an 8 channel pipette, a 16 channel pipette and a 1 ml multichannel pipette sit for partial plate work, what a fixed volume pipette and pipette sets contribute in routine repeatability, how an electronic pipette controller and an automatic pipetting machine differ from a liquid handling machine or the used liquid handlers you might buy instead, what a microplate dispenser does that no pipette should be asked to, and why pipette calibration software and pipette verification are what keep any of it honest

Specifying plate pipetting

1. Check head reach against your plates. Deep wells, skirted plates and low volume formats each impose a geometry. A head that cannot reach the bottom of a deep well, or that fouls a skirt, is unusable for that format however good it is elsewhere.
2. Cost tips per plate, not per box. A full plate head consumes a rack of tips per transfer. At the intended run rate that recurring cost frequently exceeds the depreciation on the device, and second sourcing may be restricted.
3. Match the device to how full the plates are. Partial plate work is better served by an eight or twelve channel device; a full head used on a half plate wastes tips and time. Most laboratories need both.
4. Use a dispenser where the reagent is common. Filling a plate with one reagent is a dispenser's job, not a pipette's. It is faster, uses a tube rather than tips, and is more consistent.
5. Verify plate devices as a set. A multichannel device has to be verified channel by channel, because one weak channel produces a column of outliers that looks like a biological effect. Software that records per channel results is worth having.

One weak channel, one bad column

Multichannel devices fail channel by channel, and the result is a systematic pattern across a plate that is easy to read as biology. Per channel verification is what catches it, and an average across channels hides it.

Rotating the plate between replicates is a cheap diagnostic: a pattern that rotates with the plate is biology, and one that stays put is the device.

Tips are the running cost

At plate scale the consumable bill dominates. Whether a second source of tips exists, and whether the device tolerates them, is a commercial question that should be settled before purchase.

Ask for a year of tips at your intended run rate as part of the quotation. It changes the comparison between devices more often than the specification does.

Common questions

Is a full plate head worth it?

When whole plates are transferred repeatedly, yes, because it removes ninety six chances to make an error. For partial plates and varied work it is expensive and inflexible.

Why does one column of my plate read differently?

Frequently a single weak channel on a multichannel device. Verify per channel rather than as an average, and rotate the plate once as a diagnostic.

Dispenser or pipette for filling a plate?

A dispenser, whenever the same reagent goes into every well. It is faster, more consistent and does not consume tips.

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