Introduction
First, you will need to determine if the crime scene wine has been tampered with in any way. To do this you will compare the absorbance spectrum of the crime scene wine to that of fresh wine. The absorbance spectra of chemicals can be quite unique and help to identify them.
Absorbance spectra are measured using a spectrophotometer. A spectrophotometer shines light of various wavelengths or colors through a solution. Depending on the color of the solution, it will absorb or transmit different colors.
The absorption spectrum of wine contaminated with poison should look different than that of pure wine.
Second, you will determine the concentration of poison used to taint the wine. You will use a concept called Beer’s law. The concentration of many chemicals is directly proportional to the amount of light absorbed by the chemical. By constructing a standard curve, you can determine the concentration of the poison in the wine from the standard curve.
Finally, knowing the concentration of poison in the contaminated wine, you will determine the mass of poison ingested by the victim. Using the victim’s mass, you can determine if they drank enough poison to become sick or die.
Objectives
- Analyze and interpret absorbance vs. wavelength data to identify an unknown poison in wine by comparing the spectrum with spectra (patterns) for known poisons.
- Use a mathematical model to analyze and interpret absorbance vs. concentration data and determine the concentration of a poison.
- Use evidence to explain how the presence of specific poison in wine was determined using their absorbance spectra (patterns).
- Communicate technical information about the process used to identify the presence of specific toxic metals using their emission spectra (patterns).
- Explain how a spectrometer illustrates the interdependence of science and technology and allows CSI techs to identify poisons.
Sensors and Equipment
This experiment features the following sensors and equipment. Additional equipment may be required.
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This experiment is #11 of Forensic Chemistry Experiments. The experiment in the book includes student instructions as well as instructor information for set up, helpful hints, and sample graphs and data.
