Laboratory Procedures & Safety Flashcards

What is the purpose of calibrating laboratory instruments?

Answer: To ensure measurements are accurate against a known standard

Calibration verifies and adjusts instrument output against reference standards.

Which practice best prevents cross-contamination between samples?

Answer: Using fresh tips and changing gloves as needed

Fresh consumables and clean gloves prevent carryover between samples.

A meniscus reading in a graduated cylinder should be taken at what point?

Answer: Bottom of the curve at eye level

Reading the bottom of the meniscus at eye level avoids parallax error.

What is the main purpose of a chain-of-custody record?

Answer: Track sample handling to preserve integrity and legal defensibility

It documents every person who handled a sample and when, supporting reliability of results.

If a control sample falls outside its acceptable range, what should the analyst do?

Answer: Stop, investigate, and correct before reporting results

Out-of-range controls indicate a possible system error, so testing must be halted and investigated.

Which is the preferred way to record raw lab data?

Answer: Permanent ink with corrections single-lined, initialed, and dated

Good documentation practice keeps original entries visible and attributable.

What is the recommended way to carry a glass bottle of chemical across the lab?

Answer: With a secondary container or bottle carrier

A secondary container contains spills if the bottle breaks or slips.