batch of precleaned bottles should be verified in the laboratory. The residue
analysis should be available prior to sampling in the field.
Samples should not be transferred from one sample container to another.
Transferring samples between containers may result in losses of constituents
onto the walls of the container or sample aeration.
To minimize the possibility of volatilization of organic constituents, no
headspace should exist in the containers of samples containing volatile
organics. Immediately after samples designated for volatile organics analysis
have been filled and capped, they should be checked for headspace. In most
cases, the entire sample should be emptied from the container and the container
should be refilled if headspace is noted in the sample. The container should
not be "topped off" to fill the additional headspace. If headspace is observed
after samples have been collected, field logs and laboratory analysis reports
should note the headspace, if present, in the sample container(s) at the time of
receipt by the laboratory, as well as at the time the sample was first transferred
to the sample container at the wellhead.
Splitting samples is a common practice. Normally, aliquots from the sampling
device should be alternately emptied into each container receiving a split until
the containers are full. When splitting samples for volatile organics analysis
(VOAs), each VOA container (vial) should be completely filled and sealed   
vials should not be kept open while the sample is distributed between vials.
Samples collected from a well should not be composited in one container for
subsequent transfer to other containers.
7.5.2
Sample Preservation
The QAPjP should identify the methods that will be used to preserve ground water
samples. Methods of sample preservation are relatively limited, and are generally intended to
1) retard biological action, 2) retard chemical reactions such as hydrolysis or oxidation, and 3)
reduce sorption effects. Preservation methods are generally limited to pH control, chemical
addition, refrigeration, and protection from light. Chapter Two of SW 846 provides specific
information on the required containers, preservation techniques, and holding times for aqueous
matrices. Chemical preservatives should be added to samples in the field. No sample should
be brought back to the laboratory for preservation.
Most commercial shipping containers ("coolers") leak when the interior water level
reaches the lid body interface. As a result, the carrier may refuse to ship the container. For
this reason, the Agency recommends that two polyethylene overpack bags be used in
shipping. The first will contain the sample bottles, the second the ice needed to keep the
samples at 4
o
C. If the bags are taped shut, the melt water will not reach the bottle labels or
November 1992
7 24






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