Sample Transport and Storage - Field Sampling: Principles and Practices in Environmental Analysis - page 209

Another aspect of storage temperatures is the effect on the physical condition of the
sample. Compounds in solution may precipitate at reduced temperatures and not go back
into solution when warmed. With some hydrocarbon samples cooling may result in
separation of various phases. This separation may not be reversed by heating, and may
produce analytical results that do not provide the information needed [3].
Some monitoring of the sample room needs to be done. The minimum acceptable
monitoring is to record the temperature and humidity in the room every time a sample or
batch of samples enters or leaves. This should be done on a sheet kept in the room. Each
different area of the room needs its own sheet, and all sheets must be filled in whenever a
sample is placed in the room, no matter which section it is placed in. Recording
thermometers and humidity indicators can be installed in such a way that a continuous
record of the room's conditions can be kept. If this approach is taken, a separate
instrument is needed for each area of the storage room. Alternatively, sensors could be
connected to a computer and the computer could be used to record information about the
room. A connection can be made that is wireless or with wires. A single computer can
receive and store signals from many different sensors in different parts of the storage
room. Also, the computer can be set up to notify personnel when the storage room or any
part of it is not at the proper temperature or humidity. The storage room or area thus
needs to be versatile enough to allow for all the different storage requirements of
different samples and components of interest.
Locks on the doors will provide security, as will motion sensors and cameras so that all
movement into and out of the room is controlled and recorded. This provides added
security for the samples.
8.8. ARCHIVAL SAMPLES
It may be desirable to save some samples, called archival samples, until the end of the
project or even longer. They must be kept separately from all other samples and labeled
clearly as archival samples. These are duplicates or part of samples taken at a particular
time during sampling of a field. They can be used to check the accuracy and authenticity
or estimate the original condition of the samples at a later time during the project or even
years after the termination of the project. It must be kept in mind, however, that the
samples and the analyte of interest may have changed significantly during storage. For
this reason any use of archival samples in comparison studies must be done with extreme
caution.
8.9. SEPARATION OF SAMPLES AT THE FIELD OFFICE
Field analysis will be done in the field by the sampler or sampling crew. In some cases
this may not be feasible and the samples will be taken to the field office laboratory for
analysis, and some or all of the sample or samples will be analyzed and the rest shipped
to the commercial analytical laboratory. Separation is best done as the samples enter the
storage facility by immediately placing those to be analyzed in a different place from the