escape from the cooler. This precaution may not be necessary if "blue" ice or other contained

coolants are used.

As specified in Chapter One of SW 846, a temperature history of the samples should

be maintained as a quality control measure. This is done by recording the temperature on the

chain of custody record (Section 7.6) before the sample containers are sealed for shipment.

Upon receipt of the shipment, the laboratory should record the temperature on the

chain of custody record.

Holding time refers to the period that begins when the sample is collected from the

well and ends with its extraction or analysis. Holding time is not measured from the time the

laboratory receives the samples.

7.6

Chain of Custody and Records Management

A chain of custody procedure should be designed to allow the owner/operator to

reconstruct how and under what circumstances a sample was collected, including any

problems encountered. Chapter One of SW 846 contains a complete description of chain of 

custody and records management. The chain of custody procedure is intended to prevent

misidentification of the samples, to prevent tampering with the samples during shipping and

storage, to allow easy identification of any tampering, and to allow for the easy tracking of

possession.

7.6.1

Sample Labels

To prevent sample misidentification, the owner/operator should affix a label to each

sample container. Sample labels should be sufficiently durable to remain legible even when

wet. Sample labels should contain, at a minimum, the following information:

Sample identification number;

Name and signature of collector;

Date and time of collection;

Place of collection; and

Parameters requested (if space permits).

The samples can be labeled by recording the above information directly on the sample

containers. Alternatively, the owner/operator may use multiple part labels consisting of a

unique identification number that is placed on the container. At least two copies of the

descriptive information for the samples (referenced to the identification number) should be

November 1992

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