Pumps, valves, probes, fittings, tubing and sensing components for precise sample preparation, reagent handling and instrument fluidics.
Tip-Based Dilution and Distribution with Pipetting Pumps
Application guide · Tip-based dilution
Tip-based dilution and distribution must account for every aspiration, dispense and mix cycle. A ratio written on the worksheet is not enough: the stock aliquot, diluent volume, destination capacity, mixing recovery and tip policy determine whether the prepared wells are comparable.
Engineering example: preparing eight wells with 10 μL sample and 90 μL diluent requires 80 μL sample and 720 μL diluent before overage. If one aspiration supplies all sample aliquots, include residual liquid and verify the last dispense; if each well uses a fresh tip, include pickup/ejection time and eight tips.[1][2]
01Define the liquid, receiver and complete duty before selecting the component
Translate the analytical task into an engineering duty
Use case
Inputs to define
Decision supported
One-step dilution
Sample and diluent doses, final volume and mixing cycles
Verify concentration after mixing
Serial dilution
Transfer volume, well volume and number of levels
Error propagates through every level
Aliquot distribution
Destinations per aspiration and allowed contact
Check first-to-last dispense and tip retention
02Calculate the working point and the margin the instrument really needs
Calculations to complete before prototype selection
Quantity
How to define it
Why it matters
Source requirement
dose × destinations + overage
Prevents low-level aspiration failure
Tip capacity
largest aspirated volume + air/mixing reserve
Determines one or multiple aspirations
Ratio sensitivity
stock-volume error ÷ intended stock volume
Small stock doses dominate concentration error
Use minimum, routine and maximum conditions rather than one nominal point. Include the first cycle after priming or idle, the lowest source level, the highest expected restriction and the actual receiving geometry. A nominal capacity, free-flow value or theoretical command increment is not an acceptance result.
03Map the task to a FOREACH configuration and the rest of the fluid path
04Program the full liquid cycle, including prime, wash and recovery
Prepare source and tips→Add diluent→Transfer stock/sample→Mix with defined cycles→Aliquot or continue series→Read back control results
A complete method cycle is more than the active delivery step
The exact physical order and parallel actions depend on the instrument. Retain each state in the control and verification plan.
Record valve states, motion, dwell, sensor windows and rejected recovery cycles. This makes throughput and liquid consumption auditable and prevents a fast component movement from being reported as the complete analyzer cycle.
05Design abnormal-state diagnosis before the fault occurs
Observed result, likely mechanism and useful next action
Observed condition
Likely mechanism
Engineering response
Dilution series curves
Accumulated volume error or incomplete mixing
Check each transfer level independently
Last aliquot low
Insufficient overage or retained liquid
Increase source budget or reduce aliquots per aspiration
Edge wells differ
Evaporation or timing
Control plate timing and environment
The controller should distinguish a recoverable event from a result-invalidating event. A retry is useful only after the original cause has been removed and the liquid path has returned to a verified state.
06Accept performance where the liquid is actually used
Minimum qualification plan for the integrated channel
Result
Where or how to measure
Acceptance question
Volume
First/middle/last aliquot
No position-dependent drift
Concentration
Tracer or assay across all levels
Matches intended ratio within project limit
Consumption
Liquid and tip use per plate
Meets walk-away and cost target
Test the exact liquid and complete wetted path at minimum, routine and maximum conditions.
Separate first-cycle, steady-state and post-idle results; do not average away recovery behavior.
Challenge the relevant fault and confirm the controller prevents an invalid result from being accepted.
Retain the configuration, software sequence, consumables and receiving-position result together as the qualification record.
