Inside the Crime Lab: Forensic Chemisty Unit

Summary

The forensic chemistry unit annually manages over 5,000 narcotics cases and 800 blood alcohol cases, crucial for DUI determinations. Equipped with state-of-the-art technology, including gas generators for instrument gases, they perform headspace analysis on blood samples to detect alcohol. Controlled substances are identified using a Fourier-transform infrared spectrophotometer and color tests for narcotics presence. Additionally, the unit analyzes ignitable liquids in arson investigations, employing gas chromatography-mass spectrometry for compound analysis.

Takeaways

• 🔬 The forensic chemistry unit handles a significant caseload, processing over 5,000 narcotics cases and 800 blood alcohol cases annually.
• 🧪 The unit plays a crucial role in DUI investigations, analyzing blood samples to determine alcohol content.
• 🔥 They also assist in arson investigations, analyzing ignitable liquids found in fire debris.
• 🏗️ The unit operates within a state-of-the-art laboratory equipped with advanced instruments like gas generators.
• ⚗️ Hydrogen and nitrogen are produced as carrier and fuel gases, while ultra-purified zero air is used in detectors and to purge water from instruments.
• 🧪 Blood samples for DUI cases undergo headspace analysis, where alcohol is forced into the air above the sample and then analyzed.
• 🔍 A gas chromatograph is used to determine the alcohol content in blood samples after headspace analysis.
• 🌡️ The 4ye transform infrared spectrophotometer is a common tool for analyzing controlled substances, providing structural identification in about 30 seconds.
• 🧪 Color tests are used to verify the presence of different narcotics, with specific color changes indicating the type of substance.
• 🔍 The forensic chemistry unit also uses a gas chromatograph mass spectrometer for both ignitable liquid and controlled substance analysis.

Q & A

How many narcotics cases does the forensic chemistry unit handle annually?

The forensic chemistry unit handles over 5,000 narcotics cases per year.

What is the purpose of analyzing blood alcohol cases in the forensic chemistry unit?

The purpose is to determine if a DUI (Driving Under the Influence) has been committed.

What types of gases are produced by the gas generators in the forensic chemistry unit's laboratory?

The generators produce hydrogen as a carrier gas and fuel gas, nitrogen as a carrier gas, and ultra-purified zero air.

What is the process for preparing blood samples for headspace analysis in suspected DUI cases?

Blood samples are heated to force the volatile alcohol into the air at the top of the vial, and then placed into a heated headspace autosampler.

How does the gas chromatograph determine the alcohol value of a blood sample?

The gas chromatograph determines the alcohol value by collecting a sample from the headspace and injecting it into the instrument for analysis.

What is the 4ye transform infrared spectrophotometer used for in the forensic chemistry unit?

It is used to analyze controlled substances, providing structural identification of relatively pure organic compounds.

How long does it take for the 4ye transform infrared spectrophotometer to perform an analysis?

It takes approximately 30 seconds to perform an analysis.

What do the color tests indicate in the verification of controlled substances?

The color tests indicate the possible presence of different narcotics. For example, an orange color suggests the presence of an amphetamine-like compound, possibly methamphetamine.

How does the forensic chemistry unit analyze ignitable liquids in arson debris cases?

The unit prepares samples to be heated in an oven with a carbon tab, which absorbs volatile compounds. These compounds are then extracted and analyzed using a gas chromatograph mass spectrometer.

What is the role of the carbon tab in the analysis of ignitable liquids?

The carbon tab absorbs any volatile compounds that are driven off the material during heating, allowing for the extraction and analysis of these compounds.

What additional role does the gas chromatograph mass spectrometer play in the forensic chemistry unit?

The gas chromatograph mass spectrometer is also used in the analysis of controlled substances, in addition to ignitable liquids.