CPC CPC Quality Assurance & Laboratory Procedures 1 — Questions and Answers
Question 1: What certification must a laboratory hold to perform federally regulated workplace drug testing under DOT?
- HHS (SAMHSA) certification as a National Laboratory Certification Program (NLCP) certified laboratory (Correct answer)
- CAP (College of American Pathologists) accreditation only
- CLIA (Clinical Laboratory Improvement Amendments) certification only
- ISO 15189 international laboratory accreditation
Correct answer: HHS (SAMHSA) certification as a National Laboratory Certification Program (NLCP) certified laboratory
Only laboratories certified under the HHS National Laboratory Certification Program (NLCP) are authorized to analyze federally regulated drug test specimens.
Question 2: What is the primary testing method used by certified laboratories as the initial screen for drug metabolites in urine?
- Immunoassay (Correct answer)
- Gas chromatography-mass spectrometry (GC-MS)
- High-performance liquid chromatography (HPLC)
- Enzyme-linked immunosorbent assay (ELISA) with mass confirmation
Correct answer: Immunoassay
Immunoassay is the standard initial screening method because it is fast, cost-effective, and capable of processing high volumes of specimens.
Question 3: What confirmatory testing method is required under HHS guidelines when an initial immunoassay screen is positive?
- Gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-mass spectrometry (LC-MS/MS) (Correct answer)
- A second immunoassay using a different antibody reagent
- A point-of-care device test at the collection site
- A breathalyzer confirmation for all drug classes
Correct answer: Gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-mass spectrometry (LC-MS/MS)
GC-MS or LC-MS/MS is required for confirmation because mass spectrometry identifies and quantifies specific drug metabolites with high specificity, eliminating false positives.
Question 4: Why is a split specimen collected under DOT regulations?
- To allow the donor to request independent retesting of the B specimen if they dispute the primary result (Correct answer)
- To provide a backup specimen in case the primary vial breaks during shipping
- To allow two different laboratories to test the same specimen simultaneously
- To ensure there is sufficient specimen volume for all required validity tests
Correct answer: To allow the donor to request independent retesting of the B specimen if they dispute the primary result
The split specimen (Bottle B) gives the donor the right to request an independent retest at a different NLCP-certified laboratory if they dispute the initial positive, adulterated, or substituted result.
Question 5: How long must a laboratory retain a confirmed positive specimen before it may be discarded?
- At least one year from the date of the laboratory report (Correct answer)
- At least 30 days from the date of the laboratory report
- At least five years from the date of the laboratory report
- At least six months from the date of the laboratory report
Correct answer: At least one year from the date of the laboratory report
HHS guidelines require that confirmed positive specimens be retained for at least one year to allow time for litigation or retesting disputes.
Question 6: What is the purpose of a laboratory's quality control (QC) samples in the drug testing process?
- To verify that the analytical equipment and procedures are performing accurately and within acceptable limits (Correct answer)
- To train new laboratory technicians on specimen handling procedures
- To provide reference samples for the MRO when reviewing results
- To test donors who are unable to provide a urine specimen
Correct answer: To verify that the analytical equipment and procedures are performing accurately and within acceptable limits
QC samples, including positive controls and negative controls, are run with each batch of specimens to confirm that the testing system is functioning correctly.
CPC CPC Quality Assurance & Laboratory Procedures 1
What certification must a laboratory hold to perform federally regulated workplace drug testing under DOT?