Laboratory Analyses
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measured for DIW stored in sample bottles as a QA measure. Such analyses
should be conducted, at a minimum, on a subset of bottles prior to field use and
on sample blanks during laboratory analysis.
3.2.2 Sample Processing, Preservation, and Storage
When samples arrive at the laboratory, they need to be accompanied by proper
documentation using a chain-of-custody form. An example is provided in
Appendix D. This form provides field information that includes project identification; when, where, how, and by whom the sample was collected; and information on the chain of custody that was followed. This form will need to have been
checked by the field sampler against the information written on the sample bottle
label to ensure that the information matches. We suggest a format for recording
sample information in the field and sample transfer to the laboratory. The transfer of custody from field personnel to lab personnel must be documented by
dated signatures on a chain-of-custody form. A copy of the signed form should
be kept by both project and laboratory personnel. This procedure is needed to
ensure that samples were collected and transferred to the laboratory as intended.
Samples can be misplaced before arriving at the laboratory or within the laboratory before processing, particularly if there was a sample labeling error.
Prior to the start of sample processing in the laboratory, a unique code or
sample serial number (SSN) is typically assigned by the laboratory and added
to the laboratory data sheet. A single person (plus a trained backup) is generally assigned this responsibility to ensure that an SSN is not accidently used for
more than one sample. If the SSN is assigned in the field, it is important that it
is unique. The SSN will be used by the laboratory to track the sample through
the steps of sample processing, chemical analysis, and data management.
The information on the chain-of-custody form and laboratory data sheet will
be entered into an electronic database. A variety of database software is available commercially, and some laboratories develop their own database system.
Each sample will typically be analyzed for a variety of constituents with specific processing needs that are chosen to meet stated project goals. Different
results may be obtained from the same analysis if samples are prepared for
analysis using different procedures. For example, results may differ if samples
are filtered with filters of different pore sizes or of different materials. Sample
processing can involve both preparation for analysis and preservation of the
sample; therefore, it varies among analyses. The details of processing and analyses must be established to ensure that both sample processing and analyses
done by the laboratory meet project needs.
Processing is generally accomplished by dividing the sample into several aliquots, each with its own filtration/no filtration, preservation, storage, and process and handling time requirements. For example, analysis for concentrations
86
measured for DIW stored in sample bottles as a QA measure. Such analyses
should be conducted, at a minimum, on a subset of bottles prior to field use and
on sample blanks during laboratory analysis.
3.2.2 Sample Processing, Preservation, and Storage
When samples arrive at the laboratory, they need to be accompanied by proper
documentation using a chain-of-custody form. An example is provided in
Appendix D. This form provides field information that includes project identification; when, where, how, and by whom the sample was collected; and information on the chain of custody that was followed. This form will need to have been
checked by the field sampler against the information written on the sample bottle
label to ensure that the information matches. We suggest a format for recording
sample information in the field and sample transfer to the laboratory. The transfer of custody from field personnel to lab personnel must be documented by
dated signatures on a chain-of-custody form. A copy of the signed form should
be kept by both project and laboratory personnel. This procedure is needed to
ensure that samples were collected and transferred to the laboratory as intended.
Samples can be misplaced before arriving at the laboratory or within the laboratory before processing, particularly if there was a sample labeling error.
Prior to the start of sample processing in the laboratory, a unique code or
sample serial number (SSN) is typically assigned by the laboratory and added
to the laboratory data sheet. A single person (plus a trained backup) is generally assigned this responsibility to ensure that an SSN is not accidently used for
more than one sample. If the SSN is assigned in the field, it is important that it
is unique. The SSN will be used by the laboratory to track the sample through
the steps of sample processing, chemical analysis, and data management.
The information on the chain-of-custody form and laboratory data sheet will
be entered into an electronic database. A variety of database software is available commercially, and some laboratories develop their own database system.
Each sample will typically be analyzed for a variety of constituents with specific processing needs that are chosen to meet stated project goals. Different
results may be obtained from the same analysis if samples are prepared for
analysis using different procedures. For example, results may differ if samples
are filtered with filters of different pore sizes or of different materials. Sample
processing can involve both preparation for analysis and preservation of the
sample; therefore, it varies among analyses. The details of processing and analyses must be established to ensure that both sample processing and analyses
done by the laboratory meet project needs.
Processing is generally accomplished by dividing the sample into several aliquots, each with its own filtration/no filtration, preservation, storage, and process and handling time requirements. For example, analysis for concentrations