Locate the task in the fluid path first
Arrows indicate task relationships, not that every component is connected in series in one tube. Check valve positions, pump wetted boundaries and operating states for each branch.
Define the analyte and permitted operations before selecting delivery and protection paths. Validate particle distribution, material adsorption and between-sample residue using real samples. Volume measurements establish ratios; method results confirm retention of target constituents.
Common product roles and application guides
| Product category | Role in this instrument |
|---|---|
| Syringe pump | Environmental sample aliquoting and dilution |
| Air-displacement pipetting pump | Disposable-tip environmental sample transfer |
| Multiport rotary valve | Fixed-path source and waste selection |
| Tubing connections and protection | Method-required filtration; complete transfer paths for retaining sample constituents |
Operating requirements differ by step
| Stage | Task category | Operating conditions to define |
|---|---|---|
| Transfer and aliquoting: preserve source traceability | Sampling conditions | Actual sample volume, remaining source volume, probe-tip height, aspiration/dispensing speed and system liquid |
| Dilution: verify receiving ratios and mixing | Proportion-based preparation | Collection time, preservation state, particle distribution, aliquot order, actual sample and diluent volumes, mixing and time to analysis |
| Filtration: select for the analytical target | Protection and method conditions | The method-defined analyte fraction, filter location, pore size and material, retained particles, pressure drop and first sample after replacement |
| Waste and cleaning: confirm readiness for the next sample | Discarding, washing and recovery for the next sample | Sample and wash-waste destinations, shared paths, peak drainage and maintenance requirements |
Transfer and aliquoting: preserve source traceability
Record the original vessel, preservation state and destination. Particle-containing samples may differ when aliquoted at different times; include mixing and transfer order in the program.
Dilution: verify receiving ratios and mixing
Check sample and diluent volumes separately, then assess the complete operation using blanks, spikes or ratio checks. Include preservation state, settling between aliquots and shared-path residue when evaluating the final concentration.
Filtration: select for the analytical target
Pore size, medium and position depend on the method. Check targets, adsorption and pressure drop before and after filtration, and the first sample after replacement.
Waste and cleaning: confirm readiness for the next sample
Organize destinations according to media and cleaning agents. After washing, check blanks or the next sample rather than relying on tubing appearance.
Explore configurations through product application guides
Validate the complete cycle through application results
Evaluate blanks, recovery, aliquot representativeness and restart according to the method.
| Step to validate | Measurements or observations | Priority troubleshooting checks |
|---|---|---|
| Transfer and aliquoting: preserve source traceability | Measure actual delivery at the receiver, covering routine small volumes and maximum task volume, first dose after idle, sample changes and high/low concentration sequences | Air aspiration, clots/particles, probe contact with a wall or leakage alter actual delivery |
| Dilution: verify receiving ratios and mixing | Measure sample and diluent volumes, then check the mixed sample, blanks and method-appropriate spike recovery; compare successive aliquots for settling bias. | Settling, storage changes, shared-path residue or incomplete mixing can alter the aliquot composition even when its volume is correct. |
| Filtration: select for the analytical target | Compare the target fraction before and after the method-specified filtration; check blanks, analyte loss, pressure drop and the first sample after filter replacement. | An unsuitable filter or sampling location can remove the fraction being measured; clogging and adsorption can change both composition and flow. |
| Waste and cleaning: confirm readiness for the next sample | Measure actual drainage and vessel protection, then use a blank or the next sample to verify shared-path washing recovery | Incorrect waste routing, accumulated liquid or cleaning residue can contaminate the next sample. |
Dilution metering can share general engineering methods, but field preservation, particles and analyte loss require separate checks.
Common selection and recovery questions
Why can two aliquots from the same original sample differ?
Check preservation time, mixing, particle distribution and splitting order, then material contact and shared-section residue. Record source and target vessels, and assess representativeness according to the method.
Does correct dilution volume establish acceptable preparation results?
Also check received ratio, mixing, analyte recovery and blanks. Validate filtration or phase-transfer steps separately. Volume measurement does not replace method results.