CCIL Sample Management and Preparation 5 — Questions and Answers
Question 1: Which ISO/IEC standard governs the general competence requirements for testing and calibration laboratories, including sample management practices?
- ISO 9001
- ISO/IEC 17025 (Correct answer)
- ISO 14001
- ISO/IEC 17020
Correct answer: ISO/IEC 17025
ISO/IEC 17025 is the international standard specific to testing and calibration laboratory competence, encompassing sample receipt, handling, and traceability.
Question 2: When a laboratory must store samples at -20°C for organic analysis, which container closure is MOST appropriate to prevent cross-contamination?
- Standard polypropylene snap cap
- Teflon-lined screw cap sealed with parafilm (Correct answer)
- Cork stopper wrapped in aluminum foil
- Rubber septum held by a crimp seal
Correct answer: Teflon-lined screw cap sealed with parafilm
Teflon-lined screw caps with parafilm provide an inert, solvent-resistant seal that prevents both contamination and evaporation loss during frozen storage.
Question 3: A sample for dissolved metals analysis must be filtered through what pore size before acidification?
- 0.1 µm membrane filter
- 0.45 µm membrane filter (Correct answer)
- 1.0 µm glass fiber filter
- 5.0 µm cellulose filter
Correct answer: 0.45 µm membrane filter
The 0.45 µm pore size is the internationally accepted cutoff that operationally defines 'dissolved' versus particulate-bound metals.
Question 4: In a LIMS (Laboratory Information Management System), which feature MOST directly supports sample integrity?
- Automated invoicing to the client upon sample receipt
- Barcode or RFID tracking linking each sample aliquot to its chain-of-custody record (Correct answer)
- Integration with payroll systems for analyst time tracking
- Automated selection of the cheapest analytical method
Correct answer: Barcode or RFID tracking linking each sample aliquot to its chain-of-custody record
Barcode or RFID tracking creates an automated, tamper-evident link between physical samples and their electronic records, reducing transcription errors.
Question 5: What action must be taken when a sample holding time is exceeded BEFORE analysis?
- Add fresh preservative and restart the holding time clock
- Analyze the sample and flag results as potentially compromised in the report (Correct answer)
- Discard the sample immediately without client notification
- Dilute the sample to slow further degradation
Correct answer: Analyze the sample and flag results as potentially compromised in the report
Exceeded holding times must be documented and reported to the client, as results may not be defensible but the client must make the final decision.
Question 6: Which procedure is used to determine whether a solid sample preparation method achieves acceptable analyte recovery?
- Running a calibration verification standard
- Analyzing a certified reference material or spiked sample through the full extraction procedure (Correct answer)
- Performing a method detection limit study on reagent water
- Comparing results to a historical control chart for reagent blanks
Correct answer: Analyzing a certified reference material or spiked sample through the full extraction procedure
Certified reference materials or matrix spikes processed through the complete extraction confirm that the preparation method recovers analytes efficiently from that matrix.
Question 7: When collecting air samples using sorbent tubes for VOC analysis, the MOST important parameter to record in the field is:
- Ambient relative humidity only
- Sample volume collected (flow rate × sampling time) and ambient temperature (Correct answer)
- Wind speed at the sample location
- The brand and lot number of the sorbent tube
Correct answer: Sample volume collected (flow rate × sampling time) and ambient temperature
Sample volume is essential for calculating analyte concentrations from sorbent tube measurements, and temperature affects both sampling efficiency and results.
CCIL Sample Management and Preparation 5
Which ISO/IEC standard governs the general competence requirements for testing and calibration laboratories, including sample management practices?