Environmental Sampling and Preservation
Environmental Sampling and Preservation
Analytical quality starts before the sample reaches the laboratory. Sampling design, container selection, preservation, transport and traceability determine whether a result represents the intended environmental condition.
## 1. Sampling plan Define objectives, sample locations, sample type, analytes, frequency, collection technique, required containers, preservation, field measurements, QC samples and responsibilities before fieldwork.
## 2. Grab and composite samples - Grab sample: a discrete sample collected at a specific place and time. Useful for time-specific conditions or parameters that change rapidly. - Composite sample: a combination of portions collected over time or flow. Useful for characterizing average conditions when permitted by the method and analyte stability.
Do not composite samples when the analyte, objective or approved method requires discrete sampling.
## 3. Containers and preservation Container material, filtration, preservative, cooling and holding time are analyte- and method-specific. Check the approved method before collection. Label every container clearly and avoid transferring preservation assumptions from one analyte to another.
## 4. Chain of custody Record sample ID, matrix, location, collection date/time, sampler, requested analyses, preservation, container count, custody transfers, seal condition and laboratory receipt condition.
## 5. Field quality controls Use field blanks, equipment blanks, trip blanks and field duplicates where appropriate to the sampling objective and method. Document equipment decontamination, calibration checks and any deviations.
## 6. Sample receipt checklist - Sample IDs match the request and custody record. - Containers are intact, correctly labelled and appropriately filled. - Preservation and temperature are acceptable for the method. - Holding-time requirements can be met. - Any deviations are recorded and communicated before analysis.
## 7. Traceability Link the field sheet, sample label, custody form, laboratory accession number, raw data, QC batch and final report. Retain the record according to the applicable quality system.