Forensic Science
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PRESENTATION OUTLINE
CHEMISTRY OF FORENSIC SCIENCE
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WHAT IS FORENSIC SCIENCE
• Forensic Science- the application of several sciences to investigate cases by analyzing evidence that is left at the crime scene
◦ Analyzes: fingerprints, blood, firearms, saliva, drugs, and other residue
◦ A scientific explanation of the evidence is crucial in determining the guilt or innocence of a person
◦ Forensic science has a crucial role in criminal justice
◦ Analyzes: fingerprints, blood, firearms, saliva, drugs, and other residue
◦ A scientific explanation of the evidence is crucial in determining the guilt or innocence of a person
◦ Forensic science has a crucial role in criminal justice
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FORENSIC CHEMISTRY
◦ Forensic Chemistry: includes organic and inorganic analysis, toxicology, arson investigation, and serology
◦ There are several types of techniques and instrumentation that are used; depending on the item that is being examined
◦ Forensic chemists analyze the evidence the identity of the item and determine the composition and nature of it
◦ Every substance that is collected has a unique mixture of compounds that can be identified
◦ There are several types of techniques and instrumentation that are used; depending on the item that is being examined
◦ Forensic chemists analyze the evidence the identity of the item and determine the composition and nature of it
◦ Every substance that is collected has a unique mixture of compounds that can be identified
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DRUGS ANALYSIS AND TOXICOLOGY
• Forensic toxicology deals with the investigation of toxic substances, environmental chemicals or poisonous products.
◦ this area of forensics has evolved to mean the study of illegal drugs and legal ones such as alcohol.
◦ Forensic toxicology can even identify poisons and hazardous chemicals.
◦ It deals with the way that substances are absorbed, distributed or eliminated in the body
◦ this area of forensics has evolved to mean the study of illegal drugs and legal ones such as alcohol.
◦ Forensic toxicology can even identify poisons and hazardous chemicals.
◦ It deals with the way that substances are absorbed, distributed or eliminated in the body
ARSENIC
- Forensic Science grew in the 19th century when people desperately wanted to find a way to detect arsenic in the human body
• Arsenic was very popular in the 18th century
• Ana Musa Jamir Ibn Hayyan discovered a way to convert elemental arsenic into arsenious oxide
◦ With this form arsenic could be easily added to a person's food or drink
• This led to the popularity of the poison and its use of killing people
• James Marsh became the first person detect arsenic in the body
◦ However, since the jury did not see the arsenic (a metallic gray substance) they were not convinced
• THIS CREATED THE MARSH TEST WHICH IS STILL USED TODAY
• Arsenic was very popular in the 18th century
• Ana Musa Jamir Ibn Hayyan discovered a way to convert elemental arsenic into arsenious oxide
◦ With this form arsenic could be easily added to a person's food or drink
• This led to the popularity of the poison and its use of killing people
• James Marsh became the first person detect arsenic in the body
◦ However, since the jury did not see the arsenic (a metallic gray substance) they were not convinced
• THIS CREATED THE MARSH TEST WHICH IS STILL USED TODAY
BALANCING EQUATIONS
THE MARSH TEST
• The Marsh Test contains Arsenic with a combination of Arsenic-free Zinc and sulfuric acid.
◦ The zinc, acid, and arsenic are placed in a flask
◦ It is connected to a drying tube, which allows the water vapor and arsine to pass
◦ The arsine is heated and forms arsenic
‣ The powder is black and shiny and is often referred to as an arsenic mirror
◦ The zinc, acid, and arsenic are placed in a flask
◦ It is connected to a drying tube, which allows the water vapor and arsine to pass
◦ The arsine is heated and forms arsenic
‣ The powder is black and shiny and is often referred to as an arsenic mirror
COLOR TESTING
• To detect illegal drugs, scientists use reagents to observe the color changes when the drug reacts to the reagent.
◦ For example, I used heroin and the Marquis Reagent
‣ When the reagent is added to heroin the substance becomes a dark purple
◦ However, there are several color tests that have different reagents for many illegal drugs.
◦ This is an example of a presumptive test, which means that they are suggesting the presence of a drug but do not absolutely prove it.
◦ For example, I used heroin and the Marquis Reagent
‣ When the reagent is added to heroin the substance becomes a dark purple
◦ However, there are several color tests that have different reagents for many illegal drugs.
◦ This is an example of a presumptive test, which means that they are suggesting the presence of a drug but do not absolutely prove it.
PERCENT COMPOSITION
MASS SPECTROMETER
• The Mass Spectrometer is used to determine molar mass by measuring the amount of deflection of ionized fragments traveling through a magnetic field
◦ Drug testing uses gas chromatography/mass spectrometer system that is nearly 100% reliable
◦ Percent composition is the relative amount of the elements i a compound or the percent by mass of each element in a compound
◦ I decided to find the percent composition of cocaine, which is a common drug often found in forensic science cases
◦ Drug testing uses gas chromatography/mass spectrometer system that is nearly 100% reliable
◦ Percent composition is the relative amount of the elements i a compound or the percent by mass of each element in a compound
◦ I decided to find the percent composition of cocaine, which is a common drug often found in forensic science cases
SOLUBILITY
IONIC COMPOUNDS
• Solubility testing is only used occasionally, however there are some cases that require solubility testing
◦ For drugs and explosives, testing water solubility can be helpful.
◦ Solubility testing can be a preclude to solvent extraction and separation
◦ Although solubility testing helps establish similarities between two sample, it cannot indicate what source it came from
◦ The results of solubility testing depend on different properties such as molecular size and shape, polarity, solvent strength, and diffusion,
◦ Some ionic compounds are soluble, while others are not
‣ This is useful when forensic scientists are trying to identify ionic compounds.
◦ For drugs and explosives, testing water solubility can be helpful.
◦ Solubility testing can be a preclude to solvent extraction and separation
◦ Although solubility testing helps establish similarities between two sample, it cannot indicate what source it came from
◦ The results of solubility testing depend on different properties such as molecular size and shape, polarity, solvent strength, and diffusion,
◦ Some ionic compounds are soluble, while others are not
‣ This is useful when forensic scientists are trying to identify ionic compounds.
IMPORTANCE OF LEWIS STRUCTURES
• Liquid phase extraction involves the separation of two or more substances through a process where two solvents are used
◦ The degree of polarity exhibited by a substance determines its solubility in a given solvent
◦ In the case of solubility, it means that polar salutes will dissolve more readily in polar solvents
◦ The degree of polarity exhibited by a substance determines its solubility in a given solvent
◦ In the case of solubility, it means that polar salutes will dissolve more readily in polar solvents
STOICHIOMETRY
• The stoichiometry of a particular chemical reaction does not change, regardless of the processing method
◦ Because the chemical reaction the stoichiometric ratio of reagent to product does not change
• When issues to do with yield arise, forensic scientists need to provide unambiguous answers to questions of the following sort:
◦ what is the maximum amount of drug that the accused could have made with this amount of precursor substance?
◦ what is a realistic estimate of amount of drug that could have made with this amount of precursor?
◦ how much drug could have been produced from the precursor extracted from the tablets represented now only by their tailings (insoluble remnants)?
◦ Because the chemical reaction the stoichiometric ratio of reagent to product does not change
• When issues to do with yield arise, forensic scientists need to provide unambiguous answers to questions of the following sort:
◦ what is the maximum amount of drug that the accused could have made with this amount of precursor substance?
◦ what is a realistic estimate of amount of drug that could have made with this amount of precursor?
◦ how much drug could have been produced from the precursor extracted from the tablets represented now only by their tailings (insoluble remnants)?
WORKS CITED
- "Forensic Scientist Careers, Jobs and Degree Information." Criminal Justice USA. Criminal Justice USA, 2017. Web. 11 May 2017.
- Houck, Mark M. "Forensic Chemistry." Google Books. Academic Press, 26 Jan. 2015. Web. 11 May 2017.
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WORKS CITED
- Houck, Max M., and Jay A. Siegel. "Fundamentals of Forensic Science." Google Books. Academic Press, 1 July 2015. Web. 11 May 2017.
- Murnaghan, Ian. "Forensic Toxicology." Forensic Toxicology. Explore Forensics, 15 Dec. 2016. Web. 11 May 2017.
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WORKS CITED
- Newton, David E. "Forensic Chemistry." Google Books. Infobase Publishing, 2007. Web. 11 May 2017.
- Powell, Nicholas G. "Estimating Actual Yield in Clandestine Laboratory Syntheses of Methamphetamine." Clandestine Methamphetamine Laboratory Assessment and Remediation Guideline (n.d.): 1-29. Clandestine Methamphetamine Laboratory Assessment and Remediation Guideline. Forensic & Industrial Science Limited. Web. 9 May 17.
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WORKS CITED
- Sullivan, Dan M. "Forensic Chemistry." Chemistry Explained. Advameg Inc, 2017. Web. 11 May 2017.
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