An Overview of Basic Principles of Analytical Methods - Field Sampling: Principles and Practices in Environmental Analysis - page 256

Chain of custody forms, field calibration sheets, field information forms (Figures 10.4,
10.2, and 10.3, respectively), and notes or comments from the sampling event are
enclosed in watertight containers (heavy-weight industrial-style Ziploc-type bags work
well) and placed in the container. Packing or temperature blanks and enough ice, if
cooling is called for, to prevent breakage while in transit is added. Since ice or some
other form of cooling is used for most types of samples, it is very important that the lab
receive the cooler before the ice melts or the other cooling mechanism is lost. If the
sampling takes longer than a day, the samples can be held in the coolers until completion
of the sampling event; however, it is vital that the first set of samples taken be maintained
in ice during this time.
If samples are held for any length of time, it is important that the hold times as
determined by the method are not exceeded (e.g., time from sampling to analysis). Some
specific methods as well as many of the wet chemistry methods have hold times that are
measured in hours. Most “organic” methods (analysis for organic contaminants) as well
as metal analysis methods have allowable sample hold times of days. Table 10.2 gives
maximum sampling to analysis elapse times. Once all sampling is complete and the
samples are ready to be sent, the contents of all of the coolers must be checked to make
sure they are complete. The COC sheets (see Figure 10.4) must also be checked for
completeness. This form is then enclosed in its respective individual cooler. The ice level
is checked and topped off with ice as needed, and the coolers are sealed. Coolers can
often be sent “as is” via a shipper such as United Parcel Service (UPS) or Federal
Express, or if necessary can be encased in an outer cardboard shell for shipment to the
laboratory.
FIGURE 10.4 Sample chain of custody record form.
Usually the only time there are problems with shipping are when not enough ice has
been added to the cooler or the cooler has been held up in shipping and is received by the
lab after much of the ice has melted, resulting in the temperature of samples exceeding