CCIL Sample Management and Preparation 4

Question 1

Which solvent is most commonly used for Soxhlet extraction of semi-volatile organic compounds from solid matrices?

Accepted Answer

Dichloromethane or hexane mixture

Answer

Dichloromethane or dichloromethane/hexane mixtures are standard solvents for Soxhlet extraction of non-polar and semi-volatile organics from soils.

Question 2

A sample log shows that a water sample for total coliform analysis was collected at 09:00 and delivered to the lab at 15:00. The holding time is 6 hours. Should the laboratory accept the sample?

Accepted Answer

Yes, because exactly 6 hours elapsed and it is within the limit

Answer

Exactly 6 hours is at the boundary; most protocols interpret holding time as 'within 6 hours,' so the sample is marginally acceptable if properly cooled.

Question 3

What is the primary reason biohazardous samples must be clearly labeled before entering the laboratory?

Accepted Answer

To protect laboratory personnel and ensure proper handling and disposal

Answer

Biohazard labeling is a worker safety and regulatory requirement that triggers appropriate personal protective equipment and waste disposal protocols.

Question 4

When performing solid-phase extraction (SPE) for trace organic analysis, conditioning the sorbent before sample loading serves to:

Accepted Answer

Wet and activate the sorbent to improve analyte retention

Answer

Conditioning with an appropriate solvent activates bonded-phase sorbents, ensuring consistent analyte retention and reproducible recovery.

Question 5

Which of the following BEST describes a method blank in laboratory quality control?

Accepted Answer

Analyte-free reagent water taken through the complete analytical procedure

Answer

A method blank detects reagent or laboratory contamination by processing analyte-free water through every step of the analytical method.

CCIL - Canadian Council of Independent Laboratories Practice Test

CCIL - Canadian Council of Independent Laboratories Practice Test

CCIL Sample Management and Preparation 4