How to Choose an Analytical Laboratory

Cost should not be your only consideration in choosing a laboratory. Important considerations include accreditation status, accredited methods, quality control, holding times, and proper dangerous waste disposal.


Accreditation is the best indicator that the lab has the capability to do a good job. If any analysis is not performed in-house, all supporting labs should be accredited, as well. Accreditation is not proof of the quality of all of their data. It means that the lab is capable of providing accurate, representative, comparable, complete, and defensible data.

The Lab Search database has real-time information for all accredited labs. The All Accredited Labs by Name list is a PDF document, updated periodically.

If you need a lab to use a specific analytical method, due to legal mandates or grant requirements, for example, make certain that the lab is accredited for the specific method you need. You can search our database to find which labs are accredited for a specific analytical method or list the specific analytical methods for any accredited lab. Call the lab to confirm the methods they use in their reports. The lab may be accredited for an alternate method, but that will not help if you are required to use a specified one.  If you have trouble finding an accredited lab for a specific method, you can contact us.

Quality Control

Expect the lab to report the results of quality-control tests, such as blank, standard, and duplicate samples at no extra cost. Check both precision and bias estimates to judge whether or not the lab is likely to have done accurate work. Ask for results of quality control tests done with the batch in which your samples were analyzed. If there are any questions concerning interpretation of the control results, contact us.

Holding Times

Labs must be able to meet holding-time requirements for samples. Accreditation certifies that the lab is able to meet holding times, but it does not mean that this is true for your sample. Most labs provide a form to record the time a sample was taken and by whom. When the sample is delivered to the lab, the person receiving the sample should sign your form and return a copy showing the date and time the sample was received by the lab. The lab’s report back to you should show when the sample was extracted, if an organic analysis is being done, and when it was analyzed. This establishes that holding times were met and is essential in case the data is legally challenged.

Dangerous Waste Management

Laboratories must properly manage dangerous waste. To avoid mismanagement for your samples by the laboratory, ask the lab to certify that it will dispose of the samples according to existing regulations or return the samples to you for proper disposal.

Specific Types of Analysis

Testing Your Water is a page at the State Department of Health that offers tips to well owners about water testing and sample collection.

Identify Waste by Sampling and Laboratory Analysis describes using a lab to determine if a waste can be designated as a dangerous waste.

Finding a Lab to Analyze Stormwater Samples is a page for industrial stormwater permit-holders.