Which practice helps prevent contamination when handling reagents?

Which practice helps prevent contamination when handling reagents?

• A. Always leave lids off for quick access
• B. Reuse the same pipette for all reagents
• C. Always pour from reagent bottle into a beaker, never pour reagents back into the bottle
• D. Cross-contaminate pipettes

Answer: (C)

Avoiding contamination means preventing any backflow or transfer of substances between containers and tools. When you pour from a reagent bottle into a separate beaker, you limit the chance of introducing contaminants into the stock bottle. Importantly, never pour reagents back into the original bottle after transferring a portion, because backflow can carry particles, microbes, or residues from the receiving container or pipette into the stock solution, contaminating the entire reagent batch. Using a clean pipette or new tip for each transfer also helps prevent cross-contact between different reagents. Leaving lids off, reusing the same pipette for multiple reagents, and intentionally cross-contaminating pipettes all increase the risk of introducing unwanted substances into reagents, which is why they do not help prevent contamination.

Avoiding contamination means preventing any backflow or transfer of substances between containers and tools. When you pour from a reagent bottle into a separate beaker, you limit the chance of introducing contaminants into the stock bottle. Importantly, never pour reagents back into the original bottle after transferring a portion, because backflow can carry particles, microbes, or residues from the receiving container or pipette into the stock solution, contaminating the entire reagent batch. Using a clean pipette or new tip for each transfer also helps prevent cross-contact between different reagents.

Leaving lids off, reusing the same pipette for multiple reagents, and intentionally cross-contaminating pipettes all increase the risk of introducing unwanted substances into reagents, which is why they do not help prevent contamination.