Absorbance spectra for fresh wine and crime scene wine

While teaching chemistry and physics for 34 years in public schools in Maryland, nearly every semester, students asked, “When will I use this in real life?” When I supplied a scenario for a lab activity, students could see how a topic studied in their chemistry lab could have real-world application.

For instance, it might be difficult for a student to see where absorbance spectroscopy and Beer’s law could be useful to a chemist. But, what if the technique is used to analyze poisoned wine from a crime scene? This definitely piqued the interest of my students.

The scenario: At a local dinner party, some of the guests became ill and had to be transported to the hospital. Most of the stricken guests recovered, although it took varying amounts of time for them to recover. Some guests even died. What could have stricken these people and why was the effect different?

Using a Go Direct® SpectroVis® Plus Spectrophotometer, students can compare samples of fresh wine to those collected at a crime scene. Samples of tainted wine will show absorbance spectra different from those of fresh wine. By comparing the spectra of suspected toxins with those from the crime scene, the nature of the poison can be determined.

Once the identity of the poison is determined, Beer’s law can be used to determine the concentration of poison in the tainted wine. From additional evidence from the crime scene, including estimates of the wine consumed and body mass of the victims, students then calculate the amount of poison consumed and compare this to the LD50 for that poison.

Due to the local restrictions on the presence of alcohol containing products in schools, the poisoned wine and suspected poisons are all created using food dyes. A similar activity called “Killer Cupa Joe” in the Vernier lab manual uses coffee. My students and I did this lab and used food dye as the poison.

Vernier sensors can also be used for other forensic scenarios. Future blog postings will discuss more activities.

To get a free copy of this activity, email us at chemistry@vernier.com