TTHM Sampling Procedures

Proper collection, preservation and storage of samples is needed to ensure sample integrity and representativeness. Samples are collected by trained, experienced field personnel according to guidelines. The quality of a sample result is dependant upon how the sample was handled from a physical standpoint as well as from a documentation perspective. If sample was mishandled physically, the quality of sample results can be compromised accordingly. Proper physical handling and documentation of this handling goes hand in hand with providing quality results.

Volatile Sampling Procedure


Each kit will contain:

  1. One trip blank; please do not open
  2. 3-40ml vials with ascorbic acid, preservative for neutralizing chlorine
  3. Foam holder for vials
  4. Chain-of-Custody

Note: Samples should be taken at extreme end of distribution system. And TTHM are only taken from chlorinated systems.

1. Remove any attachment from sampling source such as: hoses, filters, screens or aerators.

2. Flush the water for about 10 minutes. "Collect water and use to water plants".

3. Before collecting the sample the label on the bottle needs to contain the following information:

  1. a. Water system ID
  2. b. Water system name
  3. c. Collection date and time
  4. d. Sample location, such as address and/or sampling station

4. Reduce flow of water to collect sample. Hold vial at an angle to allow the water to flow down the inside of the vial. When vial is nearly full, Image descriptiontilt vial to vertical and slightly over fill to form a meniscus [a curved upper surface of a liquid formed by surface tension] at the top of the vial. Try to avoid over flow becuase this will wash out the preservative.

5. Carefully cap the vial with the cap liner face down. Roll or shake the vial to mix the ascorbic acid. At this time when vial is inverted, no air bubbles should be present.

7. Place the samples into the foam that has been supplied in your kit.

8. Samples are ready to be sent to the lab. Make sure samples are kept on ice and the chain-of-custody is filled out completely.

Sampling Containers

The type of sample container is of utmost importance. Containers are typically made of plastic or glass, but one material may be preferred over the other. For example, silica and sodium may be leached from glass but not plastic, and trace levels of metals may absorb onto the walls of glass containers. For samples containing prganic compounds, avoid plastic containers except those made of fluorinated polymers such as polytetrafluoroethylene [PTFE].

Some volatile compounds in samples may absorb onto the walls of plastic containers or may even leach substances from plastic. Use glass containers for all organics analyses such as volatile organics, semi-volatile organics, pesticides, PCBs and oil and grease. Avoid plastics wherever possible because of potential contamination from phthalate esters contained in plastics. Container caps, typically plastics, also can be a problem. Use foiled or teflon-lined lids.

Preservation Techniques

To minimize the potential for volatilization or biodegradation between sampling and analysis, keep samples as cool as possible without freezing. Preferably pack samples in crushed or cubed ice or commercial ice substitutes before shipment. Avoid using dry ice because if will freeze samples and my cause glass containers to break. Dry ice may also effect a pH change in samples. Keep composite samples cool with ice or a refrigeration system set at 6C during compositing.

Holding Times

Sample analysis must take place prior to the allotted maximum storage times per method. This maximum storage time is referred to as the holding time. Our performance goal is to meet 100% of holding times.

Samples should be analyzed as soon as possible after collection. The times listed in Sampling Container & Holding Time chart are the maximum time limits that the samples may be held before requested analyses are initiated. Samples may be held for longer periods if the permittee, or monitoring laboratory has data on file to show that the specific types of samples under study are stable for a longer time, and has received a variance from the person in authority. A permittee, or monitoring laboratory is obligated to hold samples for shorter times if knowledge exists showing necessity of maintenance of sample stability.

Sample Container Ordering

Completing a bottle order is the responsibility of Client service personnel. An order is completed by entering all pertinent information from the client into the LIMS. The bottle order form is generated and submitted to the bottle preparation technician. The bottle preparation technician completes the tasks listed on the bottle preparation form and acknowledges completion with the ordering party. Sample containers are now available for client pick up, shipping or courier submital. A copy of the bottle order form is included for each respective bottle order and should be submitted back to the laboratory after field activities. An example of a Bottle Order Form can downloaded from the Forms & Documents page.