|From:||CPEO Moderator <firstname.lastname@example.org>|
|Date:||Fri, 13 Oct 2000 09:51:45 -0700 (PDT)|
|Subject:||Re: [CPEO-MEF] Lab reliability help!|
[This message was posted to the list by Kenneth House <email@example.com> Pat, As an ex lab manager (for toxicity testing laboratory) at a small environmental lab I can offer you some advice. The problem that Intertek had should not discourage your confidence in most certified environmental laboratories. Interteks problems were more quality control issues which did not mean that the numbers Intertek supplied were necessarily wrong. They just could not produce the appropriate QA documentation to warrant that their technicians followed EPA methods thus reducing the confidence in the accuracy of the numbers. This created a potential compliance issue for Intertek's clients. Different states have different lab certification programs. Some states have no certification program at all. You can ask to see these certifications. EPA also certifies labs once a year with QA tests. EPA provides unknown samples to the lab and the lab analyzes the samples and reports the results back to EPA. EPA knows what's in the unknown samples and the lab's results are charted along with other labs results. The lab's results have to fall within a certain standard deviation of the mean established by all the lab's results and correlate to what EPA knows is in the sample. The results are reported to the lab's clients. These clients are generally NPDES permit holders that have to report water quality data to the EPA (through their client states environemental regulators). For obvious reasons the laboratory wants to score well on these tests. These tests measure the ability of the laboratory to follow methods consistently, it does not measure the lab's ability or desire to follow EPA Methodology on every sample. If you are concerned about lab accuracy with your particular set of samples there are a number of things you can do. 1. Split the samples between two labs. The problem here is that if the results are not close enough whose results do you believe. You can split between three or more labs if you can afford it. 2. Use field blanks spiked with a known amount of the target chemical. Do not tell the lab which one is the field blank. 3. You can spike the sample itself with a known amount of the target chemical. If you choose 2 or 3 you better know what you are doing. Both of these practices are common but do require more work and more money. If your samples are important and will be subject to close examination or potentially used in litigation the amount of QA becomes more important. This is simple explanation and I hope it helps. I have not been involved in laboratory work for several years and things may have changed over the years, hopefully for the better. A good environemental laboratory can explain their QA/QC program to you and how they can insure the accuracy of their data. If you are concerned about a conflict of interest, get a good Environemental Engineering Company to design a QA/QC program for your samples. Good Luck Kenneth House ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ You can find archived listserve messages on the CPEO website at http://www.cpeo.org/lists/index.html. If this email has been forwarded to you and you'd like to subscribe, please send a message to: firstname.lastname@example.org ___________________________________________________________ T O P I C A The Email You Want. http://www.topica.com/t/16 Newsletters, Tips and Discussions on Your Favorite Topics
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