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Chapter 4. Selecting a Laboratory and Interpreting Results. Objectives. Select an EPA-recognized lab Maintain a chain of custody Review and interpret lab results . Selecting a Laboratory. Submit samples to a lab recognized by EPA’s National Lead Laboratory Accreditation Program (NLLAP)
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Chapter 4 Selecting a Laboratory and Interpreting Results
Objectives • Select an EPA-recognized lab • Maintain a chain of custody • Review and interpret lab results
Selecting a Laboratory • Submit samples to a lab recognized by EPA’s National Lead Laboratory Accreditation Program (NLLAP) • To locate a lab • Call the National Lead Information Center (NLIC) at 1-800-424-LEAD • Visit the EPA Web site at www.epa.gov/lead/pubs/nllap.htm • See the fact sheet “Selecting a Lead Laboratory” at the end of this chapter.
Questions To Ask Laboratories • Tell the lab you will be collecting dust wipe samples for lead. • Ask: • Is the laboratory recognized to analyze for lead in dust by NLLAP? • Will sampling materials be provided? • What is the turnaround time for analysis? • Can the laboratory analyze composite samples? (If the client wants composite samples) • What is the cost per sample?
Quality Control in the Field • Submit blank wipe samples. • Duplicate, or side by side sampling can be used to check lab consistency. • Review all of your sample collection and chain-of-custody forms. • Carefully review all lab results.
Review Your Sample Collection Form • Confirm all information is recorded clearly and correctly. • Sample numbers • Sample locations • Sample dimensions • Keep a copy for your records and note blanks.
Chain of Custody • A record of each person who handles the sample from the time it is collected until it is sent to the lab. • The lead dust sampling technician is responsible for maintaining chain of custody until he or she transfers custody of the samples. • Include information on sampling form • A sample Chain of Custody form is shown on the next page, and as an attachment to this chapter.
Evaluating Laboratory Results for Single Samples • Check for appropriate units (g/ft2) • Compare results to the EPA/HUD clearance standards for lead dust: • Floors < 40 µg/ft2 passes • Sills < 250 µg/ft2 passes • Troughs < 400 µg/ft2 passes
Activity: Interpreting Laboratory Results • Turn to Attachment 4-D • Answer the questions. • Be prepared to explain your answers.
Avoiding Common Mistakes • Mistaking weight (mass) for surface loading by using incorrect units (g for g/ft2) • Not submitting blank samples • Labeling or recording in the sample log blank samples as blanks • Not maintaining a chain of custody
Summary • Select an EPA-recognized lab. • Call 1-800-424-LEAD • Visit www.epa.gov/lead/pubs/nllap.htm • Ensure that the lab is EPA-recognized for the analysis of lead in dust. • Maintain a chain of custody. • Interpret lab results.