Sample Transport and Storage - Field Sampling: Principles and Practices in Environmental Analysis - page 211

types of contaminants) will have different restrictions. For instance, there are specific
requirements for packaging oil-contaminated samples. One of these is that the inside of
the box be fitted with an oil-resistant liner. There are also limits on the size and weight of
sample containers. All these restrictions must be strictly adhered to when shipping by air.
The shipment must be accompanied by a COC form updated by various persons
handling the shipment along the way and signed by the appropriate persons in the
appropriate places. This is particularly true if a national carrier such as UPS is not used to
ship the sample. This may seem simple, but a truck driver who takes the samples to the
local airport will handle samples, and this person needs to be known. Likewise, the
shipping department at the air shipment office will receive the samples and perhaps hand
them off to another person to get them to the airplane. Indeed, there may be three or four
different people handling the box between its arrival and being placed on the airplane.
When the plane lands, the same or a greater number of people may handle the sample box
before it gets to the laboratory receiving office. All of the people handling the container
of samples need to be identified, and the length of time the sample is in their possession
must be known. The greater the number of people handling the sample box the greater the
chance that something will happen that will render the samples unusable.
8.12. STORAGE AT THE COMMERCIAL ANALYTICAL
LABORATORY
Samples will be stored at the analytical laboratory, sometimes for very short periods of
time. Normally the laboratory will have standard operating procedures for sample
handling and appropriate storage facilities. A visit to the laboratory to see how samples
are handled is recommended. It is always advisable to ascertain how long and under what
conditions samples will be stored at the laboratory between receiving and analysis.
Second, a quick walk-through of the facility is necessary. Samples lying around in a
haphazard fashion in open containers are cause for concern. Such circumstances lead to
contamination and cross-contamination of samples.
A third concern is maintaining the proper environmental conditions during this time. If
the sample temperature is to be maintained at 4°C, the appropriate cold room should be in
evidence. In some cases samples may need special environmental conditions for storage,
and the laboratory must be willing and able to provide these conditions.
8.13. CHAIN OF CUSTODY
The chain of custody (COC) is the most important component of the secure movement of
samples from the field to the laboratory to final receipt of the analytical results. Another
component associated with COC is the letter of transmittal. Such a letter is not typically a
COC, in that samples may have both a COC and a letter of transmittal. Also, a letter of
transmittal can mean different things to different people; a request for a new position in
an organization may be called a letter of transmittal, for example, and thus many of these
types of letters are unrelated to samples or safe sample movement. Although COCs may