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EPA's Region 6 Office

Serving: Arkansas, Louisiana, New Mexico, Oklahoma, Texas, and 66 Tribal Nations

Chain of Custody Guidelines


You can fill out information ahead of time except, of course, for certain items like custody record, elapsed time of sampling and gauge reading after sampling.

Container ID is the number/letter combination on the Tedlar™ bag label or the canister. Be sure and include the letter prefix with the number on the canister.

Pressure readings, both before and after sampling. All readings below zero (to the left of, or counterclockwise from "0" are in units of "inches of mercury" or "inches of Hg." For canister readings of zero or more, in the unlikely event that this occurs, just put ">0." If the reading is greater that –25" Hg (for example, -23" Hg) before you start, do not sample. Instead arrange for transfer of the canister back to the lab and a replacement.

The protective cover over the inlet refers to the canister and is a brass plug. It looks just like a nut with a plug in the center and it screws on the top. It need only be screwed on finger tight lightly and its purpose is to protect against dust and moisture getting into the inlet.

The elapsed time of sampling should be three minutes. Note if you dozed off or jumped ahead, go ahead and put the actual time down, not the time that it is supposed to be.

Both sampling events synchronous? What should be noted is anything that causes a significant difference in the time of sampling between two co located samplers. For example, you turned the valve off on the canister at the end of three minutes but for some reason it took 45 more seconds to cap the suitcase or close the black handle on top of the bucket. In this case check "no" and in the comments section, write, "canister time was 3 minutes but the bucket was 3 minutes and 45 seconds" or other description.

The thirty-second pre-pump. Some people use the timer to time out the thirty seconds and that is a good idea as long as you start the sampling at exactly ½ minute and stop it at exactly 3½ minutes.

Anything that occurs that you feel might affect the sampling such as a vehicle passing near the vicinity during sampling should be noted in the comments section.

Place the Tedlar™ bag(s), if applicable, into the box provided. Place the canister(s), if applicable, into the carriers and close the latches.

Complete the seal information. The seal information should contain the number of the canister or the number of the Tedlar bag, the same number that you put on the Chain-of-Custody. The media (canister or Tedlar™ bag) ID is put in the space designated sample number. Sign and date.

Transport and store the containers in a safe, non-contaminative place such as the front seat of your car and a closet shelf, both of which have no volatile chemicals such as cleaning agents. Do not store in the trunk of your car, the garage or a storage shed where there may be gasoline or petroleum products. Do not store in an area with temperatures in excess of 100 F.

Contact the lab or hub to arrange for an expeditious delivery of the samples. Refer to the sheets and the maps about handouts.

Sign off the samples as "Relinquished by" and date it. Insert the Chain-of-Custody in one of the containers, then seal the containers with the custody seal. The lab will complete the form after that.

If either container remains unsealed for any reason, leave the Chain-of Custody out and get a signature from "Received by" and date it. You may seal the other container but the Chain-of-Custody must show all transfers. This would be rare and would only occur if you forgot the seals, for example.

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