Locate the source, drive and receiving position for this task
Required inputs are dose per operation, total cycle volume, replenishment/bottle-change interval, backpressure and receiving geometry. Confirm liquid contact, pressure and destination along the diagram before assigning drive and connection responsibilities.
The Roche GLUC3 method lists reagent and water additions separately. Preserve that distinction when budgeting this channel: a combined reaction addition is not the volume of neat reagent. The method is an engineering example, not evidence that the original analyzer uses FOREACH components.[1]
Calculate dose, total cycle volume and replenishment time together
Select by dose, total cycle volume, replenishment interval and permissible pauses. Command resolution helps compare control margin but does not establish the minimum reliable dose. Provide actual reagent viscosity, temperature and material-contact conditions as well.
| Condition to compare | Information required | Selection affected |
|---|---|---|
| Workload per dose | Dose volume, number of doses and cuvette reception | Define the routine stroke |
| Replenishment scheduling | Usable capacity, replenishment time and test cycle | Keep replenishment out of steps that cannot be interrupted |
| Reagent condition | Actual formulation, settling or droplet retention, and standby | Define first-dose recovery |
Further technical reading
Compare product options against task requirements
The following candidate options match this page's responsibilities. Compare them against the operating conditions described, then check capacity, materials and interfaces on the product pages. Card images show representative configurations; suitability must still be confirmed at actual operating points and by application results.
| Product category | Corresponding role | Confirm before selection |
|---|---|---|
| EA standard piston pump | Finite-stroke metering | Compare configurations by routine dose, total cycle displacement and wetted materials |
| SM miniature piston pump | Discrete metering in compact installations | Check installation space first, then validate working doses and actual accuracy |
| TM ultra-miniature piston pump | Discrete metering in limited space | Check installation space and configuration before measuring actual delivery; an ultra-miniature design does not imply a smaller reliable dose |
Priming and first-dose recovery support cuvette delivery
After replenishment, bottle changes or long standby, restore an effective liquid column before dispensing working doses. Nozzle droplets or entering air may mainly affect the first dose. The controller must track replenishment state and affected cuvettes to avoid duplicate dispensing.
Keep a per-cuvette record of the reagent source, completed additions, remaining usable inventory and refill state. Distinguish a completed pump motion from actual reception, particularly at the first and final doses of a batch or during a source change.
Compare first, middle and last doses with actual reagent
Measure first, middle and final doses at the actual probe and receiving cuvette with the reagent or justified test medium. Include the first dose after replenishment, bottle changes and the longest planned idle interval; relate volume and residue to the reaction ratios, blanks and assay results.
| Validation scenario | Measurement or observation | Interpretation and action |
|---|---|---|
| Dose-to-dose differences | Measure first, middle and last doses separately | If only the first dose is abnormal, check priming and nozzle state |
| Recovery after bottle change | Change bottles and reprime through the actual path | Verify delivery to the first cuvette before resuming normal timing |
Use a volume-verification method to quantify each relevant transfer while adjusting the operating sequence. Albert and Bradshaw show why measured transfer results are useful during liquid-handler optimization; their results do not validate a particular FOREACH reagent dose or replace complete-assay testing.[11]
After an abnormality or maintenance, first identify which segment needs recovery
Source depletion, air entry, nozzle droplets or backpressure changes can affect first or final doses. Identify the affected source and cuvettes before priming, and keep recovery liquid separate from useful reagent additions.
Reconcile remaining inventory and every completed or partial cuvette addition before restarting. Restore the source and effective liquid column, verify the first useful dose, and apply the assay procedure to uncertain reactions without repeating additions already completed.
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References
View references (11)
- [1]Roche — Glucose HK Gen.3, cobas c 303 / c 503 / c 703, V7.0 (2024)
- [2]Beckman Coulter — Alanine Aminotransferase, SYNCHRON / UniCel DxC, A18452 AU
- [3]FOREACH — Piston-pump head and wetted-material selection
- [4]CDC / NHANES — Sodium, Roche Cobas 8000 Laboratory Procedure Manual (2021–2023)
- [5]FOREACH — EA Piston Pump Datasheet, capacities and test conditions
- [6]FOREACH — EA-100-PEEK configuration and specifications
- [7]Tecan — Liquid handling pump selection: a guide for lab automation engineers
- [8]FOREACH — EAS Easy-to-Degas Piston Pump Datasheet
- [9]Beckman Coulter — Glucose, AU / DxC AU, BAOSR6X21
- [10]IDEX Health & Science — Degassing and bubble control
- [11]Albert and Bradshaw — Importance of Integrating a Volume Verification Method for Liquid Handlers: Applications in Learning Performance Behavior (2007)