Multichannel Pipettes: Consistency and Error Prevention

A multichannel pipette transfers several aliquots in one movement, but does not guarantee that every channel delivers the intended volume correctly. A poorly seated tip, different immersion depth or local fault may affect only some wells. The useful approach is therefore to check the complete system: pipette, tips, liquid, vessel, operator and work sequence. Each channel’s result must remain identifiable; an overall average can conceal an important difference.

This guide addresses operational use of multichannel pipettes in pharmaceutical laboratories, particularly air-displacement models. It provides preparation checks, a diagnostic matrix and a simulated numerical case. It does not replace the model’s instructions, analytical method or calibration procedure. Selection, use and competence fall within the scope of ISO 8655-10; the details below are reasoned GuideGxP recommendations, not a reproduction of the standard. [1–4]

When a multichannel pipette improves the workflow

The advantage arises when several positions require the same transfer in a coordinated sequence. Distributing a common reagent, transferring aliquots from a compatible plate or performing an ordered series may reduce movements. However, assess the benefit across the whole task: preparation, tip changes, identification, checks and interruptions. There is no universal percentage of time saved.

Before choosing the number of channels, map the samples and the route across the plate. A configuration convenient for reagent addition may be unsuitable for samples with different remaining volumes. Using only some channels is acceptable only if that configuration is supported and assessed for the intended use: simply leaving some cones empty does not establish that everything else remains unchanged.

Also consider the time between the first and last additions. If the method is sequence-sensitive, plan the order, any mixing and the handling of pauses. A channel does not necessarily correspond to a fixed row: the relationship depends on plate orientation. Recording that relationship makes it possible to reconstruct which samples could be affected by an anomaly.

Compatibility: check the combination, not just the volume

ISO 8655-2 considers the pipette together with its selected tips and other essential parts; ISO 8655-6 covers the complete system in the reference gravimetric procedure. This approach avoids treating the consumable as an irrelevant accessory. A “universal tip” claim alone does not demonstrate sealing, alignment and performance of the combination being used. [1,2]

Compare channel spacing, well pitch, opening diameter and tip length. Check the approach without forcing the head or pressing tips onto the bottom. Plates with the same number of wells may differ in shape, depth and usable volume; a position suitable for one vessel is not automatically valid for another.

The reservoir must allow every active tip to reach the liquid throughout the sequence, including as its level falls. Assess available volume, inaccessible liquid and stability on the bench. For distinct samples, use compatible separate vessels: a common reservoir is not a solution if it destroys sample identity or introduces cross-contamination.

Checklist before the first aspiration

The following original checklist helps identify inconsistent configurations before samples are involved. The laboratory should incorporate it into its own procedure, assigning responsibilities and criteria proportionate to use. A tick records a check actually performed; it does not replace evidence of performance.

• Identify the pipette, authorised use status, range and selected mode.
• Confirm tip type and compatibility; check uniform seating and absence of visible damage.
• Verify plate, strip or reservoir geometry with every active channel.
• Define plate orientation, sample-to-well map and correspondence with the channels.
• Check available volume and the minimum operating level established for that combination.
• Specify technique, any pre-wetting, rhythm and handling of challenging liquids.
• Prepare the dispensing route, tip changes, waste handling and response to interruptions.
• Confirm that the operator understands stop signals, anomaly recording and authorised resumption.

Reassess the combination when a relevant element changes, such as tip, plate, liquid or volume. A change may require a targeted check even if the pipette still carries the same calibration label. Do not turn every change into complete requalification as a matter of principle: document which aspects of performance could change and what evidence is needed.

Aspirate under comparable conditions

Observe the entire row of tips. In a common vessel, a tilted head may leave one end less deeply immersed; as liquid is depleted, the fault may appear only during the final aspirations. Different levels in separate vessels require even closer assessment. No tip should aspirate air or be pressed against the bottom.

PTB report DKD-R 8-1 identifies inclination, immersion depth, rhythm, waiting time after aspiration and operating force among operator-related influences. The numerical conditions of its calibration procedure are not automatically instructions for every sample. For actual use, define conditions compatible with the instrument and method and verify them in the intended context. [3]

Look for bubbles, apparently unequal filling and liquid loss, without confusing visual observation with volume measurement. Transparent liquids, tip geometry and reflections can make comparison misleading. Pre-wetting, where specified, should be consistent across channels; liquid temperature, the environment and pipette warming can influence air-displacement transfer. [3,5]

Dispense while retaining position and sequence

Bring each tip to its own well while maintaining the intended geometry. Wall contact, any below-surface dispensing and residual-liquid handling depend on the approved technique. Do not improvise a different position for an outer channel merely because it is easier to reach. An inadequately supported plate or rotated wrist can make an apparently single movement asymmetric.

Follow the defined order and distinguish aspiration from mixing. A pause, telephone call or reservoir change must leave the last completed position identifiable. For viscous, volatile or foaming liquids, consult the article on pipetting techniques and challenging liquids: increasing the number of channels does not remove the technique’s limitations.

Residual liquid does not always mean the same thing. It may be expected in reverse pipetting, or may indicate incomplete dispensing or non-uniform behaviour. Assess it against the chosen procedure. Do not add a second discharge into the “suspect” well alone without a defined rule: this could introduce another difference that cannot be reconstructed.

Individual channel checks: which results to retain

Separate three questions: does the channel deliver a suitable volume? Does it do so with sufficient repeatability? Do channels show differences relevant to the application? Averaging all deliveries answers these questions poorly if channel identity is lost. DKD-R 8-1 provides for records by test volume and by channel in its calibration procedure. [3]

For routine checks, define the volume, liquid, tips, mode, channels, conditions, replicates and criteria before testing. Neither the number of repetitions nor the tolerance is universal. A quick visual check may detect an obvious fault, but is not equivalent to calibration. Likewise, a check with water alone does not demonstrate suitability for every analytical matrix.

Retain individual results, channel identity and plate position alongside the summary. If a colorimetric signal or reader is used, distinguish the transfer contribution from those of mixing, reagent, plate and reading system. A difference between two wells does not automatically prove a pipette fault. The check should be designed to discriminate between these causes.

An original matrix to guide diagnosis

The actions below are investigative options, not confirmed diagnoses or repair instructions. Conduct checks in a controlled setting, without blindly continuing on samples. Change one variable at a time where possible and retain results that do not support the initial hypothesis as well.

Simulated case: a 99 µL average does not describe eight channels

Consider an arithmetic example, not experimental data: selected volume 100 µL; hypothetical mean volumes for channels 1 to 7 of 100 µL each; mean volume for channel 8 of 92 µL. The average across channels is (7 × 100 + 92) / 8 = 99 µL. The overall mean deviation is −1%, whereas channel 8 deviates by −8%.

No tolerances, repeatability or uncertainties have been assigned: these numbers cannot support a conformity statement. They show only that a summary can dilute a local anomaly. An average close to the selected volume does not demonstrate that every aliquot is suitable; equally, channels that match one another could share a common deviation.

In the simulated case, the laboratory retains the map and suspends the affected use. It first checks tip seating and compatibility, then determines whether the difference persists with the correct configuration. If it persists on the same channel, an instrument check is requested; if it follows a plate position, the investigation extends to the method. The overall volume is not changed to compensate for one channel, because that would also alter the other aliquots.

To assess previous activities, the laboratory reconstructs which samples passed through the affected channel, under what conditions and since the last reliable evidence of correct operation. Decisions on results require the applicable quality procedure; they do not follow automatically from the example’s 92 µL value alone. The investigation must distinguish observation, hypothesis and demonstrated findings.

Cleaning, maintenance, training and return to use

Define cleaning and maintenance according to materials, liquids and instrument instructions. Do not assume that the entire pipette is autoclavable or that any lubricant is compatible. Disassembly, replacement and adjustment require authorised personnel and records. Following an intervention, verify functions that could have been affected before resuming work.

Training should cover preparation, alignment, level checks, recognition of anomalies and interruption handling. Competence and training are within the scope of ISO 8655-10; reading the procedure alone does not demonstrate correct execution. GuideGxP recommends observed assessment using representative configurations, with targeted feedback and documented results. [4]

Return to use should connect the problem, intervention, evidence and decision. Record which channels and conditions were checked, who assessed the outcome and any remaining restrictions. A new label or absence of visible leaks is not enough to close every anomaly; the selected check must address the identified cause and impact.

Operational conclusions and boundaries

A multichannel pipette is useful when geometry, sequence and control are designed together. Preparing the map, checking the pipette–tip–vessel combination, observing all channels and retaining distinguishable results make investigations more effective. Explain differences through appropriate checks, avoiding improvised compensation and averages that erase information.

This guide does not set acceptance limits for specific methods and is not a complete calibration procedure. Apply cited standards within their scope and relevant version. To place transfer within the overall workflow, consult the Liquid Handling & Sample Preparation hub.

Sources and scope of use

1. ISO. ISO 8655-2:2022 — Pipettes. Official catalogue: scope and status; licensed full text not consulted.
2. ISO. ISO 8655-6:2022 — Gravimetric reference measurement procedure, corrected version June 2022. Official catalogue; provisions not accessed are not reproduced.
3. PTB/DKD. DKD-R 8-1 — Calibration of piston-operated pipettes with air cushions, edition 12/2011, revision 1, English version 2024. Sections 3, 6, 7 and 8.9; metrological procedure for air-displacement pipettes.
4. ISO. ISO 8655-10:2024 — User guidance, competence, training and POVA suitability. Public scope consulted; full text not consulted.
5. PTB/DKD. DKD-E 8-1 — Experimental study on the calibration of piston-operated pipettes with air cushion, 2013 study, revision 1 republished in 2025. Experimental influences, not universal operating limits.

Sources checked on 30 September 2026. Checklist, matrix and case are original GuideGxP material; the case is simulated and does not represent laboratory data.