Can derivative UV-visible spectroscopy be used in toxicology?
The application of derivative UV-visible spectroscopy in forensic toxicology The application of derivative UV-visible spectroscopy in forensic toxicology J Forensic Sci Soc.
How is spectroscopy used in forensic science?
Spectroscopy is the scientific field dedicated to studying the relationships between matter and radiation. A form of non-destructive testing, spectroscopy is widely applied in many science and industry areas to understand various specimens' molecular make-up. This article takes a look at how spectroscopy is used in forensic science.
Can UV/Vis spectroscopy be used for the examination of inks and fibres?
On this basis, the use of UV/vis spectroscopy has much to recommend it for the forensic examination of inks and fibres, though thin layer chromatography (TLC) is also widely used as a complementary method in both cases.
What is the difference between UV/Vis and conventional UV spectroscopy?
The UV/vis spectrum directly quantifies the colour of the sample and the technique is reliable and fairly straightforward to carry out experimentally. Conventional UV/vis spectroscopy is destructive, though only very small quantities of material may be required.
What is the main purpose of UV spectroscopy?
UV-Vis Spectroscopy (or Spectrophotometry) is a quantitative technique used to measure how much a chemical substance absorbs light.
When was UV light first used in forensics?
Reflected Ultraviolet Imaging System is a popular imaging system used by crime scene investigators and lab technicians to identify and analyze clues. The credit for designing this system goes to HORIBA France (a renowned optics firm formerly known as Jobin Yvon) that invented it in 1997.
What can UV light detect?
The lights cause materials such as bacteria, urine, seminal fluids and blood, to "fluoresce," so that the naked eye can detect them. Typically, UV lights are used to test surfaces especially when there is a disease outbreak or any sudden increase in occurrences of a specific disease at a particular time or place.
How does UV light detect blood?
A bloodstain exposed to UV light absorbs all light of that bandwidth and does not reflect back – that is to say, it does not fluoresce in any way. Thus the stain will appear black under UV.
When were UV lights invented?
Ultraviolet lamps are usually housed in quartz or special glass that transmits ultraviolet radiation more readily than ordinary glass. Ultraviolet lamps were developed for medical use after the germicidal qualities of ultraviolet light were discovered about 1900 by the Danish physician Niels Ryberg Finsen.
When was the blacklight invented?
William H. Byler is credited with inventing the black light in 1935, and according to the University of Central Missouri, Byler graduated there in 1927 with a major in chemistry and physics.
How did Ritter discovered UV light?
DISCOVERY OF ULTRAVIOLET In 1801, Johann Ritter conducted an experiment to investigate the existence of energy beyond the violet end of the visible spectrum. Knowing that photographic paper would turn black more rapidly in blue light than in red light, he exposed the paper to light beyond violet.
Why is it that ultraviolet light analysis is recommended by the FBI as the first choice to examine biologically contaminated evidence?
Ultraviolet light analysis and other optical examination techniques are recommended by the Federal Bureau of Investigation guidelines as the first choice to examine biologically contaminated evidence . This is because ultraviolet analysis is not destructive.
What is UV spectroscopy?
UV-VIS (ultraviolet-visible) spectroscopy or spectrophotometry is the study of the interaction of light with matter at electronic levels. It ranges from the vacuum level ultraviolet region i.e. 180nm to visible region i.e. 780nm. UV spectrum extends from 180nm to 400nm whereas the visible region ranges from 400nm to 780nm.
What is the most commonly used detector in UV visible spectroscopy?
The most commonly used detector in UV visible spectroscopy is a photomultiplier tube. Repetition of the dynode is structured with a slight potential difference at a particular angle. The incoming photon strikes the cathode, after knocking out several electrons from the dynodes every time.
How does a single beam spectrophotometer work?
Single beam uv-vis spectrophotometer has a single beam as the name indicates. The incident light coming from the source is passed through a monochromator then that incident monochromatic light moves through a slit. Then it passes through the sample solution. Where some of the incident light is absorbed by the sample while other is transmitted. That transmitted light is detected by the detector. The detected light is then amplified, recorded, and then displayed on a suitable readout device. Spectrum is plotted and the λ max is located.
What does zero mean in UV spectroscopy?
The zero in UV spectroscopy indicates the total transmittance while baseline is the amount of radiation absorbed by the cuvette and the sample solution.
What material is used in ultraviolet spectroscopy?
Fused silica and quartz cuvettes are most commonly used in ultraviolet spectroscopy as they are transparent in the ultraviolet region i.e. quartz can not absorb ultraviolet light so are used in ultraviolet spectrophotometers. Plastic and glass materials absorb ultraviolet light which interferes with the results.
Why does fluorescence have a negative absorption value?
The negative value of absorption indicates that the sample is having an impurity in it, which causes interference with the result. The fluorescence caused by the impurity can enhance the value of transmitted radiation as compared to incident radiation. That is the reason it gives a negative absorption value.
What is the transition of electrons at different levels by absorption of radiation from ultraviolet to visible region?
This line graph of various absorptivities on specific levels of radiations is because of the absorption capacities of compounds at certain levels. These levels are called regions of absorption and the compounds are termed as chromophores.
Why do we use spectroscopy to analyze paint?
Spectroscopy to analyze automotive paints. Paint bits are useful forensic evidence as they are usually encountered during vandalism, car accidents, and burglaries. The trace materials are compared to draw association of a crime scene to a potential suspect .
What is FTIR spectroscopy used for?
While FTIR spectroscopy can be used to examine fibers based on their measurement conditions, fiber type, and their overall structure. IR spectroscopy identifies the difference in acrylic fibers based on their excitation wavelengths, which makes the analytical technique efficient for studying the matrix of textile fibers.
How to identify automotive coatings?
Furthermore, automotive coatings consisting of both organic and inorganic chemical compounds can be identified by Raman and FTIR spectroscopy techniques. Whereas the additives for these compositions on the automotive coating can be analyzed through SEM/EDX and ICP-MS techniques.
What is the purpose of Raman spectroscopy?
Raman spectroscopy serves the field of forensic toxicology as an analytical tool to detect and quantify drugs in biological specimens. This technique is efficient in providing confirmatory testing for biological matrices as the technique is not influenced by the presence of water, where the matrices have high contents of the molecule.
How long does it take for a drug to be detected by Raman spectroscopy?
To illustrate, D'Elia, et al. found that Raman spectroscopy can detect drugs to the lowest micrograms within 7 days of deposition. Furthermore, the purity of the drug as well as the chain of custody, the two crucial things uphold in forensic laboratories, are preserved for the technique's non-destructive nature.
What is glass evidence?
Glass pieces exist as trace materials encountered during criminal cases of burglary, traffic accidents, and theft. The examination of this physical evidence usually involves elemental analysis, after two glass materials are found similar based on physical examination. Analytical techniques such as SEM-EDX, FTIR, XRF, and ICP-OES and ICP-MS are utilized in forensic laboratories to obtain information on the elements involved within these glass materials.
Which analytical technique does not destroy the small amounts of evidence?
An optimum analytical technique that does not destroy the small amounts of evidence is spectroscopy. The evidence, ranging from biological fluids, drugs to trace materials found at the crime scene can be examined as they are preserved with this technique. Furthermore, no sample preparation is needed for this particular technique, ...
How is Spectroscopy Used in Forensics?
Forensic science studies and analyzes potential evidence from crime scenes to reveal important information about a crime that may have taken place. It is essential not to damage or significantly alter this evidence, and so forensic scientists must use non-destructive testing (NDT) methods such as spectroscopy to perform their analysis.
Why is spectroscopy important in forensics?
Another benefit of forensic science is that spectroscopy can be used to understand samples’ molecular make-up without removing the sample from the crime scene.
Why is spectroscopy used in law enforcement?
Because it is non-destructive and can be performed safely, spectroscopy can also be used to analyze potentially hazardous unknown substances.
What is spectroscopy in science?
Image Credit: Rabbitmindphoto/Shutterstock.com. Spectroscopy is the scientific field dedicated to studying the relationships between matter and radiation. A form of non-destructive testing, spectroscopy is widely applied in many science and industry areas to understand various specimens' molecular make-up.
What can be safely investigated with spectroscopy?
Suspicious or alarming powders, liquids, or even gases at crime scenes can be safely investigated with spectroscopy, which will enable forensic scientists to precisely identify what they contain. These examples serve to illustrate the rich application of spectroscopy in forensic science.
What is the most important achievement of spectroscopy?
One among many notable successes of spectroscopy was in the discovery and later acceptance of the quantum mechanical theory , driven experimentally by Niels Bohr when he used spectroscopy to analyze and describe the hydrogen’s atomic structure.
Who invented spectroscopy?
The famous English scientist Sir Isaac Newton first used the word “spectrum” to refer to the array of colors in a rainbow. Although white light’s tendency to split into multiple colors when directed through a glass prism has been studied since Roman times, Newton is generally regarded as the father of modern spectroscopy.
Introduction
Fibres
- Trace evidence such as fibres, hair or glass fragments has particular forensic significance due to its ease of transfer and subsequent persistence, particularly on textile substrates. Notable cases in the UK where fibre evidence has been of crucial importance include the murder of Sarah Payne in 2001 and securing the conviction of Steve Wright for multiple murders in Suffolk in 2006.1 Alt…
Inks
- The purpose of forensic ink examination is usually to determine whether the writing on a document has been altered by establishing whether the ink-line from one part of the text is the same as or different to that from another part. Although several ink types and technologies are now in use, the traditional ball-point pen is still responsible for a large proportion of the writing fr…
Conclusion
- UV/visible spectroscopy plays a key role in the discrimination of colour in the forensic analysis of fibres and inks. The application of chemometrics, however, is vital in many cases to enhance such discrimination and to put it on a quantitative basis so providing objective justification for the conclusions of the analyst.
Acknowledgements
- The support of the Nuffield Foundation and the contributions of Sarah Sherratt and Vladimir Zholobenko to the inks research are acknowledged.
References
- http://www.forensic.gov.uk/html/media/case-studies/(link is external)
- M.C. Grieve, T.W. Biermann and K. Schaub, “The individuality of fibres used to provide forensic evidence–not all blue polyesters are the same”, Sci. Justice 45(1), 13–28 (2005). https://doi.org/10....
- K. Wiggins, R. Palmer, W. Hutchinson and P. Drummond, “An investigation into the use of calc…
- http://www.forensic.gov.uk/html/media/case-studies/(link is external)
- M.C. Grieve, T.W. Biermann and K. Schaub, “The individuality of fibres used to provide forensic evidence–not all blue polyesters are the same”, Sci. Justice 45(1), 13–28 (2005). https://doi.org/10....
- K. Wiggins, R. Palmer, W. Hutchinson and P. Drummond, “An investigation into the use of calculating the first derivative of absorbance spectra as a tool for forensic fibre analysis”, Sci. Justice 4...
- C.D. Adam, S.L. Sherratt and V.L. Zholobenko, “Classification and individualisation of black ballpoint pen inks using principal component analysis of UV-vis absorption spectra”, Forensic Sci. Int....
