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

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