ANALYTICAL CHEMISTRY IN FORENSIC SCIENCE
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This document summarizes analytical chemistry techniques used in forensic science laboratories. It describes how forensic labs are divided into areas like biology, chemistry, DNA, and toxicology. The chemistry lab analyzes samples like blood, urine, and drugs using techniques like Fourier transform infrared spectroscopy, gas chromatography/mass spectrometry, liquid chromatography/mass spectrometry, and atomic absorption spectroscopy to identify organic and inorganic compounds. These analytical techniques help determine the chemical composition of evidence and whether detected substances caused or contributed to death.
ANALYTICAL CHEMISTRY IN FORENSIC SCIENCE
- 1. ANALYTICAL CHEMISTRY IN FORENSIC SCIENCE PRESENTED BY, PRADEEP S JAISWAL. MSC. PART-2. SEMESTER -4 PAPER-4.
- 2. CONTENTS: • INTRODUCTION. • FORENSIC LABORATORY. • CHEMICAL LABORATORY.: Tested Samples. Methods of analysis Instruments. Chemicals. Glass ware. Interpritation of result. refrences.
- 3. • The word forensic comes from the Latin adjective forensis, meaning "of or before the forum." • The term "forensic" is effectively a synonym for "legal" or "related to courts". Forensic
- 4. In Some classification the laboratory was divided into four main areas of investigation: Biology. Chemistry. DNA . Drugs / Toxicology. Forensic Laboratory
- 5. Forensic Laboratory Other classification, The laboratory is divided into many areas of investigation: 1. Fingerprint lab. 2. Trace evidence lab. 3. Serology / DNA labs. 4. Materials lab. 5. Firearms lab. 6. Photography lab. 7. Chemistry lab. 8. Others labs.
- 6. • A chemistry unit is present in any laboratory and is used to test samples of: • Blood and urine for alcohol, • Drugs and poisoning. • Synthetic materials such medicines, • Dyes and stains. • Specialists in the area of chemistry also rely on FTIR, gas chromatographs, mass spectrometers, atomic absorption and microscopes to identify chemicals. Chemistry Laboratory
- 7. 7 Chemistry Laboratory Main……. 1. Building. 2. Utility. 3. Furniture. 4. Tested Samples. 5. Methods of analysis 6. Instruments. 7. Chemicals. 8. Glass ware. 9. Staff.
- 8. Tested Samples • There are two main classes of chemical compounds: Organic compounds : • Are based on carbon (containing the element carbon. • As a structural backbone) and are found in living things. Inorganic compounds : • Are those based on other elements. • From the point of view of forensic science, both organic and inorganic compounds are found in items of evidence. • The techniques used for determination of chemical composition of such evidence often depend upon whether the component compounds are organic (derived form living tissue or material) or inorganic.
- 9. Tested Samples Biological samples include: • Blood. • Urine. • Hair. • Nails. • Saliva. • Tissues. Non-biological samples include: • Unidentified pills, • Powders, • Liquids, and • Gases.
- 10. Methods of Analysis • All methods are standard methods. • The selected methods will be suitable for Lab samples. • Reference for all methods. • QC applications for Methods of analysis.
- 11. Instruments All the required instruments chosen according to: • Test methods. • Up to date version. • Good reputation instrument manufactures. • Technical's Comparisons results between suppliers.
- 12. Analytical Techniques Compound Sample nature Method Gases & Volatile Compounds Simple mixtures, known compounds GC " Complex mixtures, unknown compounds GC / MS Non-volatile organic compounds Simple mixtures, known compounds HPLC " Complex mixtures, unknown compounds LC / MS Toxic Metals AAS / ICP Some of the more common analytical techniques used in forensic toxicology
- 13. Main Instruments • FTIR. • GC/MC. • LC/MS. • HPLC. • Microscope. • Atomic Absorption. All the required instruments chosen according to test methods:
- 14. Fourier Transform Infrared • FTIR Spectroscopy is a molecular spectroscopy which is used to characterize both organic and inorganic evidence. • The sample is bombarded with infrared radiation. • When the frequency of the infrared radiation matches the natural frequency of the bond, the amplitude of the vibration increases, and the infrared is absorbed. • The output of an infrared spectrophotometer charts the amount of light absorbed vs. the wavelength, typically with units of percent transmission and wave numbers(cm-1).
- 15. FTIR main parts Source Laser Interfero meter Detector
- 16. FTIR Applications • FTIR is a valuable forensic technique because of its detection • sensitivity and versatility. • Chemicals from a variety of sample types including : • Blood, • Paints, • Polymer coatings, • Drugs and • Both organic and inorganic contaminants can be identified
- 17. GC-MS • Functions by separating the molecules within the sample compound into their most elemental particles. • Allowing some types of molecules to pass into the mass spectrometer more rapidly than others. • When the molecules move into the mass spectrometer, they are broken down into ionized fragments.
- 18. GC-MS Fragments • The mass spectrum for 2,6-dimethylaniline is shown below the chromatogram as an example. • Peaks in the mass spectrum are representative of fragments from the parent compound induced by the instrument during detection. • Every compound gives a unique mass spectrum, thus allowing for structural assignments to be made.
- 19. GC -MS Applications Forensic applications of GC/MS include identification and detection of : • Explosives. • Investigations of arson. • Fire, and blasts or explosions. • Environmental analysis. • And drug detection.
- 20. LC-MS • In LC–MS, there has been an explosion in the range of new products available for solving many analytical problems. • particularly those applications in which non- volatile, labile and/or high molecular weight compounds are being analysed.
- 21. • LC–MS is a well-established technique for explosives in associated complex matrices such as post-blast residues and in environmental samples such as soil and plant material extracts. • between structurally related textile dyes which were previously indistinguishable by UV–VIS absorption profile or by micro spectrophotometry. LC-MS APPLICATION
- 22. HPLC • chromatographic technique that can separate a mixture of compounds and is used in biochemistry and analytical chemistry. • identify, quantify and purify the individual components of the mixture.
- 23. HPLC Applications • Some of the most popular applications to evidence analysis are: • Drugs. • Soils. • Inks. • Explosives.
- 24. Visible Microscope • Visible microspectrophotometry is a very useful tool in the forensic analysis of many kinds of trace evidence. • It combines a microscope with a spectrophotometer so that the light absorption properties of a very small sample can be recorded.
- 25. • The technique is particularly valuable in the investigation of: • Hair. • Textile fibers. • And paint. • Colored inks. • which are typically of microscopic dimensions. A fiber, for instance, may have a diameter of only around 20 micrometers. Visible Microscope Applications
- 26. Atomic Absorption • A technique for determining the concentration of a particular metal element in a sample. • The technique can be used to analyze the concentration of over 70 different metals in the prepared solution.
- 27. AA main parts 1. Lamp. 2. Atomizer. 3. Monochromator. 4. Photomultiplier tube. 5. Optical system. 6. Automatic gas control.
- 28. Identification of a poison Qualitative Analysis of an Inorganic Compound: • A poison is a substance that can cause, to an organism, injury, illness or death when a sufficient quantity is present. • This indicates that any chemical substance in sufficient quantities can act as a poison even table salt.
- 29. Atomic Absorption Applications Forensic and clinical applications: Blood, urine, serum, tissue, bone and hair • Al, Cr, Cu, Zn, As, Se, Cd, Pb, Hg • Some elements toxic • Al, As, Cd, Hg, Pb • Some essential • Se, Fe, Zn, Cr • Some vital at low levels, toxic if high • Cu, Zn, Se
- 30. Other Instruments • UV-VIS spectroscopy . • polarizing light microscopy. • Atomic Force Microscopy (AFM). • X-Ray Photoelectron Spectroscopy (XPS). • Thin layer chromatography . • Scanning Electron Microscope (SEM). • Polymerase chain reaction PCR.
- 31. Chemicals All chemicals prepared according to the : • stander methods of analysis. • The purity of required chemicals. • Quantities of chemicals per one year. • MSDS for all chemicals. • Hazardous notes about all chemicals. • Quantities of chemicals per one year.
- 32. Glass ware • All Glass ware prepared according to the stander methods of analysis. • The grid of required glass wares. • Amounts of glass wares. • Storage requirements for items.
- 33. Interpretation of Results • The specific questions that must be answered are whether the concentrations • of any analyte or combinations of analytes were: • Sufficient to cause the death? . • Sufficient to have affected the actions of the decedent so as to have caused the death? . • Insufficient to have any involvement in the cause of death?. • Insufficient to protect the individual from an underlying mechanism of death such as an epileptic seizure?.
- 34. REFRENCES: