PCR Reagents & Consumables Management Flashcards

What is the recommended practice for managing PCR reagent inventory to ensure that older lots are used before newer ones, reducing waste and avoiding expired materials?

Answer: First-in, first-out (FIFO) stock rotation

FIFO stock rotation ensures that reagents with earlier expiration dates are consumed before newer stock, minimizing waste and reducing the risk of using expired materials.

Which type of PCR tube cap is recommended to prevent aerosol contamination and sample evaporation during high-temperature cycling steps above 90°C?

Answer: Flat optical caps with secure snap-lock closure

Secure flat optical caps or locked dome caps create an airtight seal that prevents evaporation and condensation artifacts during the high-temperature denaturation steps of PCR.

When a new lot of PCR master mix is received, what validation step must be performed before using it on clinical or diagnostic specimens?

Answer: Parallel lot comparison using known positive and negative controls

Parallel lot comparison against the previous lot using characterized positive and negative controls confirms that the new lot performs equivalently before use on patient samples.

What is the primary reason filter (aerosol-resistant) pipette tips must be used for all PCR setup steps in a molecular diagnostics laboratory?

Answer: To prevent aerosol from entering the pipette barrel and contaminating subsequent reactions

Filter tips contain a hydrophobic barrier that prevents aerosols containing nucleic acids from being aspirated into the pipette barrel, preventing cross-contamination between samples.

Which practice should be followed when aliquoting PCR reagents such as primers and probes to minimize lot-to-lot variability and reagent degradation over time?

Answer: Create single-use working aliquots and store stock reagents separately at -80°C

Single-use aliquots prevent repeated freeze-thaw cycles that degrade oligonucleotides, while keeping stock reagents at -80°C preserves their integrity long-term.

In a CAP-accredited PCR laboratory, what is the required documentation when disposing of expired or failed lot PCR reagents?

Answer: A written record noting lot number, expiration date, reason for disposal, and disposal method

CAP accreditation standards require written documentation of reagent disposal including lot number, expiration date, reason for disposal, and method to maintain a complete quality audit trail.