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 analytical targets and sampling budgets before selecting renewal, discard or return strategies. A closed path, pinched tube and aseptic sampling are not equivalent. Confirm contamination boundaries for the complete path and procedure.
Common product roles and application guides
| Product category | Role in this instrument |
|---|---|
| Syringe pump | Sampling-volume and transfer control |
| Fluidic valves | Sampling, refresh and receiver routing; sampling-tube shutoff |
| Bubble and pressure detection | Sampling signals the controller can associate with sample identity |
| Tubing connections and protection | Method-specified sample treatment; connections from process port through pretreatment to analysis |
Operating requirements differ by step
| Stage | Task category | Operating conditions to define |
|---|---|---|
| Sample collection: assess representativeness using paired samples | Sample renewal and representativeness | Analyte, sampling interval, renewal of stagnant sections, discard-volume budget and permitted pretreatment |
| Filtration: retain or remove material according to the analyte | Protection and method conditions | Target components, pore size/material, filtration area, pressure drop, check-valve cracking pressure and leakage |
| Pretreatment: preserve timing and actual-volume records | Proportion-based preparation | Actual volumes of original sample, diluent or internal standard; concentrations at each stage; mixing and resampling conditions |
| Flexible-tube control: validate pinching and replacement procedures | Tubing-control conditions | Tubing material, OD/wall thickness, pressure/vacuum, pinch-off and cycle count |
Sample collection: assess representativeness using paired samples
Record sampling interval, retained volume and discard destination. Compare target results with reference samples before setting renewal time.
Filtration: retain or remove material according to the analyte
Filter adsorption, increasing pressure drop and replacement can change a sample. Record method-specified particle treatment and before/after filtration differences.
Pretreatment: preserve timing and actual-volume records
Arrange dilution, preservation or other treatment according to the analytical method. Measure recovery and blanks, and record sample arrival time.
Flexible-tube control: validate pinching and replacement procedures
Pinching reduces liquid contact with the valve body, but tubing, fittings and maintenance remain within the contamination-control boundary. After installation, check closure, sealing and cleaning or sterilization procedures.
Explore configurations through product application guides
Validate the complete cycle through application results
Compare process and collected samples, checking target retention, contamination and reactor-volume changes.
| Step to validate | Measurements or observations | Priority troubleshooting checks |
|---|---|---|
| Sample collection: assess representativeness using paired samples | Measure renewal time at the analytical or receiving interface and assess target representativeness using paired samples | Old-sample mixing, settling, adsorption or insufficient renewal time can make the sample unrepresentative of its source. |
| Filtration: retain or remove material according to the analyte | Evaluate targets before and after filtration, blanks, recovery or method-specified metrics. Check increasing pressure drop, backflow protection and recovery after replacement. | Clogging, adsorption, leaks or excessive cracking pressure can alter delivery or method results |
| Pretreatment: preserve timing and actual-volume records | Measure each branch's delivery, received ratio and mixing uniformity separately, then check assay response | Small-volume errors, shared residual liquid or inadequate mixing may alter the actual ratio |
| Flexible-tube control: validate pinching and replacement procedures | Measure closed-state leakage, open-state resistance and tubing condition after cycling. Check complete-path sealing and contamination-control boundaries after maintenance. | Tube fatigue, incorrect installation or differential pressure outside configuration limits may prevent closure |
Removing cell aggregates may change the measured target. Reduced valve-body contact through a pinch valve does not make the entire path sterile.
Common selection and recovery questions
Should every online sample be filtered?
Define whether the target is cells, biomass or dissolved constituents, then choose retained and removed fractions according to the method. Check adsorption, pressure drop and replacement recovery rather than selecting solely to prevent clogging.
Does a tubing-pinch arrangement establish sterile sampling?
Also assess the complete boundary formed by tubing, fittings, sampling ports, assembly and maintenance under actual procedures. Validate pinch sealing separately from the path after cleaning or sterilization.