Quiz 3 - New Perspectives in Forensic Science

Lecture 5 & 6

What can nutritional deficiency lead to?

Pathophysiological conditions

What is involved in forensic elemental analysis?

Drugs, medicine, environmental quality and impact, potential biomarkers

What are the potential biomarkers of meth users?

Fe, Cu, Cr, and Se
→ Higher levels of Cu have been shown in previous studies

What are common elemental analysis techniques?

AAS, AES, inductively coupled plasma-MS, X-Ray fluorescence spectroscopy

What is atomic spectroscopy?

Quantitative and qualitative technique used to determine types of elements from samples that are decomposed via flame, furnace, or plasma

→ IWhatnvolve the measurement of absorbed or emitted radiation at a particular wavelength rather than recording spectra

What is the difference between AAS and AES?

AAS → Atoms absorb a fraction of light from the source and the rest reaches the detector

AES → The emission that results is from the loss of energy by atoms in a thermally excited state

What is LIBS?

A type of AES called laser-induced breakdown spectroscopy

→ Uses a high-energy pulsed laser as an excitation source

What is AAS used for in forensics?

1. Glass analysis

2. Gunshot residue (Samples dissolved with HNO3)

3. Toxicology (AES is also used)

What is ICP-AES/ICP-OES?

Uses the inductively coupled plasma to produce excited atoms and ions that emit electromagnetic radiation at wavelengths characteristic of a particular element

How is ICP-AES used in forensics?

For food items with heavy metals, wines, oils and trace metals bound to proteins

What is ICP-MS?

Detects metals and non-metals at low concentrations by ionizing the sample with ICP and then analyzing those ions

Why is LA-ICP-MS good for glass analysis?

Avoids complete destruction of the specimen and the use of hazardous reagents

What can LA-ICP-MS be used for in forensics?

1. Glass analysis

2. Paints (Qualitative and semi-quantitative)

What type of ICP is used for GSR analysis?

ICP-MS for damaged bullets, analyze Sb/Pb ratio, and Pb composition

What is X-Ray fluorescence spectroscopy?

Non-destructive technique that uses an X-ray photon to strike an atom, dislodging an electron from one of its inner shells, in which excess energy is released

→ X-ray fluorescence peak can be correlated to a specific element

What is a K_α X-ray?

Excess energy released when atom fills the vacant K shell with an electron from the L shell, and the electron drops to the lower energy state

What is a K_β X-ray?

Excess energy released when atom fills the vacant K shell with an electron from the M shell, and the electron drops to the lower energy state

What can X-ray fluorescence be used for in forensics?

1. Glass analysis

2. GSR particles

3. Rock and soil analysis

4. Determine purity of element

What is nanotechnology?

The science of designing, producing, and using structures and devices having one or more dimensions of about 100 millionth of a millimeter (100 nanometers) or less

What are the three types of nanotechnology?

Natural, Incidental, and Engineered

Why is nanotechnology used in forensics?

Due to its low detection limits, detection of minute variations, and analysis of physical evidence on the nanoscale

How can nanotechnology be used for explosive evidence?

Can detect specific explosives, and nanoparticulate colloids via SERS 

How can nanotechnology be used for fingerprint detection and visualization?

Can enhance latent fingerprints
→ Photoluminescent CdS semiconductor nanocrystals capped with dioctysulfo-succinate

→ ZnO-SiO₂ nanopowder

What surfaces can SPR be used on?

Semi-porous and non-porous surfaces

What type of evidence can be detected with nanotechnology?

1. Explosives

2. Fingerprints

3. Counterfeits

4. Drugs

5. DNA

6. PMI (Up to 96 hours)

7. Hair, fiber, and document analysis (Nanoscope AFM)