Criminalistics - Chapter05.doc

<CHAP NUM="5" ID="CH.00.005">chapter 5

<FM><TTL>Organic Analysis</TTL><KTSET>

<TTL>Key Terms</TTL>

<KT>chromatography</KT>

<KT>compound</KT>

<KT>electromagnetic spectrum</KT>

<KT>electrophoresis</KT>

<KT>element</KT>

<KT>enzyme</KT>

<KT>fluoresce</KT>

<KT>frequency</KT>

<KT>gas (vapor)</KT>

<KT>infrared</KT>

<KT>inorganic</KT>

<KT>ion</KT>

<KT>laser</KT>

<KT>liquid</KT>

<KT>matter</KT>

<KT>monochromatic light</KT>

<KT>monochromator</KT>

<KT>organic</KT>

<KT>periodic table</KT>

<KT>phase</KT>

<KT>photon</KT>

<KT>physical state</KT>

<KT>proteins</KT>

<KT>pyrolysis</KT>

<KT>solid</KT>

<KT>spectrophotometry</KT>

<KT>sublimation</KT>

<KT>ultraviolet</KT>

<KT>visible light</KT>

<KT>wavelength</KT>

<KT>X-ray</KT></KTSET>

<TTL>Learning Objectives</TTL>

<P>After studying this chapter you should be able to:

<OBJ><P><INST><              </INST>Define and distinguish elements and compounds</P></OBJ>

<OBJ><P><INST><              </INST>Contrast the differences between a solid, liquid, and gas</P></OBJ>

<OBJ><P><INST><              </INST>Define and distinguish organic and inorganic compounds</P></OBJ>

<OBJ><P><INST><              </INST>Understand the difference between qualitative and quantitative analysis</P></OBJ>

<OBJ><P><INST><              </INST>Describe and explain the process of chromatography</P></OBJ>

<OBJ><P><INST><              </INST>List and describe the parts of a gas chromatograph</P></OBJ>

<OBJ><P><INST><              </INST>Explain the difference between thin-layer chromatography, gas chromatography, and electrophoresis</P></OBJ>

<OBJ><P><INST><              </INST>Understand the differences between the wave and particle theories of light</P></OBJ>

<OBJ><P><INST><              </INST>Describe the electromagnetic spectrum</P></OBJ>

<OBJ><P><INST><              </INST>Name the parts of a simple absorption spectrophotometer</P></OBJ>

<OBJ><P><INST><              </INST>Describe the utility of ultraviolet and infrared spectroscopy for the identification of organic compounds</P></OBJ>

<OBJ><P><INST><              </INST>Describe the concept and utility of mass spectrometry for identification analysis</P></OBJ></P></OBJSET></FM>

<CASE NUM="1" TY="CS"><TTL>Death by Tylenol</TTL>

<P>In 1982, two firefighters from a Chicago suburb were casually discussing four bizarre deaths that had recently taken place in a neighboring area. As they discussed the circumstances of the deaths, they realized that each of the victims had taken Tylenol. Their suspicions were immediately reported to police investigators. Tragically, before the general public could be alerted, three more victims died after taking poison-laced Tylenol capsules. Seven individuals, all in the Chicago area, were the first victims to die from what has become known as <ITAL>product tampering.</ITAL> A forensic chemical analysis of Tylenol capsules recovered from the victims’ residences showed that the capsules were filled with potassium cyanide in a quantity ten thousand times what was needed to kill an average person. It was quickly determined that the cyanide was not introduced into the bottles at the factory. Instead, the perpetrator methodically emptied each of twenty to thirty capsules and then refilled them with potassium cyanide. The tampered capsules were rebottled, carefully repackaged, and placed on the shelves of six different stores. The case of the Tylenol murders remains unsolved, and the $100,000 reward offered by Tylenol’s manufacturer remains unclaimed.</P></CASE> <OBJSET>

<BM><P>In the previous chapter, some physical properties were described and used to characterize glass and soil evidence. Before we can apply other physical properties, as well as chemical properties, to the identification and comparison of evidence, we need to gain an insight into the composition of matter. Beginning with knowledge of the fundamental building block of all substances—the element—it will be convenient for us to classify all evidence as either organic or inorganic. The procedures used to measure the properties associated with each class are distinctly different and merit separate chapters for their description. In later chapters, we will continually return to these procedures as we discuss the examination of the various kinds of physical evidence. This chapter will be devoted, in large part, to reviewing a variety of techniques and instruments that have become the indispensable tools of the forensic scientist for examining organic evidence.</P>

<H1>Elements and Compounds</H1>

<P><KT>Matter</KT> is anything that has mass and occupies space. As we examine the world that surrounds us and consider the countless variety of materials that we encounter, we must consider one of humankind’s most remarkable accomplishments the discovery of the concept of the atom to explain the composition of all matter. This search had its earliest contribution from the ancient Greek philosophers, who suggested air, water, fire, and earth as matter’s fundamental building blocks. It culminated with the development of the atomic theory and the discovery of matter’s simplest identity, the <KT>element.</KT></P>

<P>An element is the simplest substance known and provides the building block from which all matter is composed. At present, 118 elements have been identified (see <LINK LINKEND="TB.05.001">Table <TBLIND NUM="1" ID="TB.05.001"/>5–1</LINK>); of these, 89 occur naturally on the earth, and the remainder have been created in the laboratory. In <LINK LINKEND="FG.05.001">Figure <FIGIND NUM="1" ID="FG.05.001"/>5–1</LINK>, all the elements are listed by name and symbol in a form that has become known as the <KT>periodic table.</KT> This table is most useful to chemists because it systematically arranges elements with similar chemical properties in the same vertical row or group.</P>

<TBL NUM="1" ID="TB.05.001"><TTL><INST>Table 5–1  </INST>List of Elements with Their Symbols and Atomic Masses</TTL>