Spectrophotometry in Forensics

In the current era of forensic science, where crime scene materials are accessible in trace amounts, forensic spectroscopy has functioned as a non-destructive alternative to traditional destructive procedures in crime evidence examination.

Through forensic spectrophotometry, analysts can intensely study crime scene evidence using the power of electromagnetic imaging. Spectrophotometry is the process of scientifically and objectively measuring color and radio wavelengths. It is more dependable than using human eyes and provides reproducible results on an easy-to-understand scale. With spectrophotometry, forensic examiners can distinguish between the chemical composition, material, and even brand of a piece of evidence by examining how the sample reflects wavelengths.

Spectrophotometry is a preferred method of forensic analysis due to its non-destructive analytical abilities. This process is versatile enough to analyze fibers, hairs, and forensic materials such as bodily fluids, drugs, and fingerprints. Spectrophotometers also have the advantage of not requiring sample preparation before analysis.

What Is Spectrophotometry?

Spectrophotometry refers to the process of analyzing samples using electromagnetic waves. Spectrophotometers test how the light refracts and reflects off a particular material and investigate its color, infrared and ultraviolet properties, and more. Using spectrophotometry, you can tell the difference between similar samples of hairs, fibers, drugs, bodily fluids, and fingerprints.

Spectrophotometry works by taking a sample and measuring the intensity of light when a beam passes through it. Since each compound transmits and absorbs light differently, it is possible to identify the true nature of a substance by analyzing this wavelength. Depending on the nature of the sample, it can be studied using a UV-visible or infrared range spectrophotometer.

How Is Spectrophotometry Used to Solve Crimes?

Spectrophotometry is a gold forensic analysis standard used by the FBI and the American Hazardous Material Response Unit. The spectrophotometric process is essential for telling apart two nearly indistinguishable samples. Most forensic analysts use UV/vis spectroscopy in forensic science to examine inks and fibers, and thin-layer chromatography is a complementary method.

With spectroscopy in forensics, trace evidence analysis, including hairs, fibers, and glass, is highly accurate. Even samples as small as 10-30 mm fiber can undergo examination to determine their chemical composition and whether they're natural or synthetic. Forensic ink examinations are a perfect candidate for spectroscopic analysis. Wavelength examination can identify the unique hues in inks found at the scene and whether they're similar to specific brands of storebought pens. Spectrophotometry is a non-destructive and safer alternative for identifying inks compared to chromatography.

Spectroscopy has various applications in forensic science, including:

Gun Powder Identification

When investigators can't recover a weapon in a shooting crime, smokeless powder will be critical evidence for forensic analysis. Smokeless powder is the propellant deposited by the cartridge. Lab techs will use a spectrophotometer to identify the information on smokeless powder and then compare it to a database of various types of smokeless powder used in different cartridges. This identification will significantly help the criminal investigation.

In the forensic laboratory, Fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectroscopy (GS-MS) techniques determine the chemical properties of particles collected from the crime scene. FTIR analysis aids in detecting the energetic component, nitrocellulose, by detecting the functional groups in the smokeless powder.

Fibers Identification

Fiber, like hair, is evidence when found at a crime scene. Fibers as evidence in forensic science have probative significance because they reveal linkages or relationships between suspects or victims. UV visible spectroscopy is one of the most remarkable techniques for studying fiber since it does not damage the material. Any fiber discovered at the crime scene may disclose a suspect's or victim's contact information. The tiny UV-visible spectroscopy technology allows us to compare and uncover similarities between textile threads.

Most forensic laboratories utilize a microscopic UV-visible spectrophotometer. This method is more beneficial for fiber analysis than Raman spectroscopy. Fibers are widely studied using the tiny UV-visible spectrophotometer method. FTIR spectroscopy examines fibers according to their kind, structure, and measurement circumstances. IR spectroscopy can also detect changes in acrylic fibers depending on their excitation wavelengths. This approach is excellent for investigating textile fiber matrixes.

Forensic Spectroscopy Techniques

Forensic science analyzes evidence at the molecular level using a vast arsenal of spectroscopic tools. These approaches use the interaction between electromagnetic radiation and matter to disclose a substance's chemical makeup.

Raman Spectroscopy

Raman spectroscopy can evaluate solids, liquids, and gases, making it suitable for various forensic materials. It needs little sample preparation, conserving significant evidence for later analysis. Notably, portable Raman equipment enables on-site examination of crime scenes.

Ultraviolet (UV) Spectroscopy

This approach is critical in determining the presence of bloodstains due to their unique UV light absorption. In addition, UV spectroscopy analyzes fingerprints, patterned injuries, and ignitable liquids during fire investigations.

Gas Chromatography-Mass (GC-MS) Spectroscopy

This effective approach isolates and identifies distinct components in a mixture by analyzing their mass-to-charge ratios. In anti-doping labs, GC-MS is used to identify banned performance-enhancing substances in athletes.

Nuclear Magnetic Resonance (NMR) Spectroscopy

This approach is beneficial for evaluating restricted substances and their precursors. NMR spectroscopy also detects metabolites and illicit substances, making it an effective technique in drug analysis.

Infrared (IR) Spectroscopy

This non-destructive approach determines the chemical makeup of organic substances such as hair, paint, and fibers. It is also helpful for analyzing trace elements such as gunshot and fingerprint residue.

Purchase Spectrophotometers From HunterLab

HunterLab has driven the spectrophotometry industry forward for over 60 years, and we're eager to show you the most impressive forensic spectrophotometers we have. Our equipment is calibrated to the highest standards so you can glean invaluable insight from the crime scene and identify even the most challenging evidence. Whether you're comparing textile, fiber, bodily fluid, or ink, our efficient products can help you sort through the evidence and finish your investigation as soon as possible.

Contact HunterLab to learn more about our forensic spectrophotometry solutions today.