Sample Transport and Storage - Field Sampling: Principles and Practices in Environmental Analysis - page 212

be thought of as being associated with evidentiary forensics samples, they are equally
valuable and important in environmental and geological sampling.
The COC accounts for where the sample originated, where it has been, who has
handled it, and what conditions it has been exposed to. It should prevent loss, misplacing,
and tampering with the sample in any way. It will also help prevent samples from either
being analyzed for the wrong constituents or being subject to the wrong procedures. To
accomplish this it is best to minimize the number of people involved in the COC and
sample handling. The more people handling a sample or container of samples, the greater
the likelihood of contamination, loss, or mislabeling of the samples. If one person is
sampling and is also responsible for storage, that person does not necessarily need to sign
the COC each time he or she handles the sample. Each time the sample or samples are
transferred to a new location, however, this needs to be fully noted. The dates, times, and
conditions of transfer need to be recorded, even if the same person is doing all the work
[3].
The COC starts in the field with taking the sample and putting it in the sample
container. The sample is recorded in the project notebook, given a number, and recorded
on a COC form. This form then stays with the sample until the analytical results are
reported back to the entity requesting the analysis. If bar codes are used, a code label can
be placed on the COC form [4]. If a group of samples are to be shipped as a batch, a
batch COC needs to be prepared. Individual sample COCs go in the batch box with the
samples, and the batch COC is signed as needed by persons handling the box. Again, if
bar codes are used a bar code for the box can be prepared and used to keep track of the
box. An illustration of the type of information needed for a COC form is given in Figure
8.3. (A more detailed COC is given in Chapter 10.)
At each step of this process a responsible person should be designated to receive
samples, sign the COC forms, and put samples in the appropriate storage area or
transmittal container. This person will also be the contact person during the time the
samples are in his or her possession. In small firms, in which there are a limited number
of employees, this may seem unnecessary. It is not; but it need not be a complicated
procedure. In large firms it is essential that persons handling samples be identified and all
the time the samples that are in their possession be accounted for.
8.14. COMPUTER CHAIN OF CUSTODY
A COC can and should be set up using computers. This should be done even though a
detailed paper COC is also maintained. One advantage of a computer COC is that it can
be quickly accessed from many locations when a problem occurs. Software can also
allow for the insertion of additional written descriptions and explanations in such a way
that they do not interrupt the flow of the COC because they are readily available as “pop-
up notes” that appear with the push of a button. This is much more useful than shuffling
through numerous pages of information to find a needed explanation or description. The
information in the pop-up could be about storage facilities, changes in temperature, or
other conditions that might