05 Biotechnology Laboratory Methods
Learn how sample handling, measurement, controls, analytical methods, documentation, and quality practices work together to produce trustworthy biotechnology laboratory results.
Follow the laboratory workflow
Laboratory work is commonly organized into three connected phases. Errors or weaknesses in one phase can affect the validity of results produced in later phases.
Pre-analytical: Define the question and test plan; collect or receive the sample; assign an identifier; check acceptance criteria; and prepare, transport, and store the material appropriately. Mix-ups, contamination, degradation, or unsuitable samples can invalidate later testing.
Analytical: Prepare reagents and samples, run the procedure with appropriate controls, collect raw observations, and assess whether the run met its acceptance criteria.
Post-analytical: Review and interpret results, investigate unexpected findings, report them with appropriate units and limitations, and retain records and materials according to the applicable procedure.
For a protein measurement in a cell-culture sample, confirm the sample identity and storage history, run the assay with a series and controls, check that the run is acceptable, and then report the result with its units and any relevant dilution factor. A technically successful instrument run cannot correct a sample that was mislabeled or degraded before testing.
Make measurements trustworthy
describes how close a result is to an accepted reference value, while describes how closely repeated measurements agree. A method can be precise but inaccurate; for example, a balance may consistently read too high. Replicate measurements help assess , while suitable reference materials or calibrated standards help assess .
compares instrument readings with known references and, where needed, establishes corrections. It is not the same as routine performance checks: a laboratory may check a pipette or temperature-controlled instrument between calibrations to confirm that it remains fit for use. Equipment records should identify the equipment, the or check performed, the date and result, and any action taken.
Measurement traceability depends on a documented chain of calibrations to suitable references. Both the chain and the measurement’s uncertainty matter, not simply the name of a reference organization. Use appropriate units, record dilution factors and instrument settings, and avoid reporting more digits than the method supports.
expresses the range of values reasonably associated with a result. Its importance depends on the measurement’s purpose: small differences may matter in a tightly controlled assay but be irrelevant in a rough screening measurement.
Use controls and replicates
Controls and standards answer different questions and should be chosen for the method and sample type.
A blank contains no target analyte and helps reveal background signal or contamination from reagents and equipment.
A is expected not to produce the target-specific result. In a nucleic-acid amplification assay, a no-template control can reveal contamination in reagents or setup.
A contains material expected to produce a result. It checks that key parts of the procedure can work, but does not prove that every sample is free from error.
A has an assigned value and helps establish or check the relationship between signal and amount. Standards used for are not automatically independent quality controls; a separate control can provide a stronger check on the measurement process.
repeat measurement of the same material and help assess analytical variation. Biological replicates represent independent biological samples and help capture biological variation. Repeating one sample many times does not replace independent biological samples.
Define acceptance criteria before interpreting results. If a required control fails, do not treat the run as valid just because sample results look plausible. Follow the procedure for investigation, repeat testing, and documentation.
Choose and evaluate analytical methods
Select a method according to what must be identified or measured, the sample matrix, the required sensitivity, and the intended use of the result. Each method has considerations that can affect interpretation.
Spectrophotometry measures absorbance or another optical signal and is often used to estimate concentration or follow reactions. Use a suitable blank and range; turbidity and interfering substances can affect readings.
PCR and quantitative PCR (qPCR) amplify a selected DNA sequence. qPCR tracks signal during amplification to estimate the starting target amount. Include appropriate positive, negative, and no-template controls; contamination, inhibition, and assay design can affect interpretation.
Gel electrophoresis separates nucleic acids or proteins, commonly by size and charge-related properties. A molecular-size marker helps interpret bands, but a band at the expected size alone may not establish identity or purity.
Chromatography separates mixture components as they move through a stationary phase with a mobile phase. Retention behavior and detector response can support identification and quantification, but suitability depends on the method and standards used.
Immunoassays, such as ELISA, detect or quantify a target using specific binding reagents and a measurable signal. Relevant blanks, standards, and controls should be included; cross-reactivity and matrix effects may influence results.
Microscopy and cell-based assays show cell or sample features or measure a biological response. Standardize sample preparation, imaging or assay conditions, and scoring; biological variability is often important.
DNA sequencing determines the order of nucleotides in a DNA sample. Quality checks, reference comparisons, and controls help distinguish genuine sequence information from technical artifacts.
Establish method suitability
establishes that a method is fit for its intended use. confirms that an established method performs as expected in a particular laboratory or setting.
Depending on the purpose, relevant characteristics may include selectivity, , , working range, detection or quantitation limits, and robustness. The appropriate characteristics and acceptance criteria depend on the method and its use; not every method requires the same studies.
Maintain traceable records
Documentation allows another trained person to understand what was done, what was observed, and how the result was obtained. Record work as it occurs, using the approved procedure and current forms or electronic systems.
Records typically identify the sample, operator, date and time, method version, equipment, reagent or reference-material lots, raw observations, calculations, control results, deviations, and final review. Keep raw data as well as processed results so that calculations and interpretations can be checked.
Correct errors transparently: preserve the original entry, make the correction traceable to its author and date, and explain it when needed. Do not silently overwrite, erase, or reconstruct missing observations. Electronic systems should preserve access controls and audit trails appropriate to their use. Document control should ensure staff use approved procedures and can identify superseded versions.
Build quality and investigate failures
A laboratory quality system connects competent personnel, controlled procedures, maintained equipment, suitable reagents, records, assessment, and improvement. Practical quality practices include:
Training staff and assessing competency for assigned work.
Following written procedures for sample handling, testing, equipment, and reporting.
Monitoring equipment and managing reagent storage, expiry, and lot changes.
Reviewing controls and results before release or use.
Recording deviations and nonconformities, investigating likely causes, and taking corrective action when warranted.
Reviewing procedures and performance periodically, including through audits or other independent checks where appropriate.
When a run fails, first protect the integrity of the result: flag or hold affected data, document the event, and follow the laboratory’s investigation procedure. Check the sample, controls, reagents, calculations, instrument status, and procedural steps. Repeat testing only when justified; repeating a test without understanding the failure may reproduce the same error. Requirements vary with the laboratory’s purpose and the applicable regulations or quality standards.
Trustworthy results depend on the entire workflow, from sample receipt through reporting. Appropriate , units, awareness of uncertainty, effective controls, fit-for-purpose methods, clear records, and a functioning quality system help make results interpretable, reproducible, and open to review.