ETC ETC Laboratory Analysis & Forensic Science 1 — Questions and Answers
Question 1: Which type of analysis uses ninhydrin reagent to develop latent fingerprints on porous surfaces such as paper?
- Amino acid-based chemical development (Correct answer)
- Cyanoacrylate fuming
- Alternate light source illumination
- Magnetic powder dusting
Correct answer: Amino acid-based chemical development
Ninhydrin reacts with amino acids left by skin oils to develop purple-colored latent prints on porous surfaces like paper.
Question 2: What is the purpose of a control sample in forensic laboratory analysis?
- To establish a baseline for comparison and validate test results (Correct answer)
- To replace the original evidence during testing
- To document the chain of custody of the sample
- To store evidence in a refrigerated environment
Correct answer: To establish a baseline for comparison and validate test results
A control sample provides a known baseline so analysts can confirm the test is performing correctly and results are valid.
Question 3: Which analytical technique is considered the gold standard for identifying and quantifying drugs in seized samples?
- Gas chromatography-mass spectrometry (GC-MS) (Correct answer)
- Thin-layer chromatography (TLC)
- Colorimetric field testing
- Infrared spectroscopy only
Correct answer: Gas chromatography-mass spectrometry (GC-MS)
GC-MS separates compounds by gas chromatography then identifies them by mass spectrometry, providing highly accurate drug identification.
Question 4: An evidence technician submits a white powder to the lab. Which presumptive test would indicate the possible presence of cocaine?
- Scott test (cobalt thiocyanate) (Correct answer)
- Marquis reagent test
- Duquenois-Levine test
- Mecke reagent test
Correct answer: Scott test (cobalt thiocyanate)
The Scott test produces a blue color in the presence of cocaine, serving as a presumptive indicator before confirmatory analysis.
Question 5: What does a forensic toxicology report primarily establish in a criminal investigation?
- The presence, identity, and concentration of substances in biological specimens (Correct answer)
- The manner of death as determined by a coroner
- The timeline of events at the crime scene
- The psychological profile of the suspect
Correct answer: The presence, identity, and concentration of substances in biological specimens
Forensic toxicology analyzes biological specimens such as blood and urine to detect, identify, and quantify drugs, alcohol, and poisons.
Question 6: When submitting biological evidence to a forensic lab, which packaging material is preferred over plastic bags?
- Paper bags or paper envelopes (Correct answer)
- Sealed plastic zip-lock bags
- Aluminum foil wrapping
- Vacuum-sealed plastic pouches
Correct answer: Paper bags or paper envelopes
Paper packaging allows moisture to escape, preventing mold and bacterial growth that would degrade DNA and other biological evidence.
ETC ETC Laboratory Analysis & Forensic Science 1
Which type of analysis uses ninhydrin reagent to develop latent fingerprints on porous surfaces such as paper?