Inside the Crime Lab: Forensic Chemisty Unit

Denver Police

26 Mar 201703:35

Summary

TLDRThe 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.

Outlines

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🔬 Forensic Chemistry Unit's Role and Capabilities

The Forensic Chemistry Unit is responsible for handling over 5,000 narcotics cases annually, necessitating the analysis of tens of thousands of items. It also processes over 800 blood alcohol cases each year to determine DUI offenses. The unit supports the Denver police and fire departments in arson investigations by analyzing ignitable liquids. It operates within a state-of-the-art laboratory equipped with gas generators that produce hydrogen, nitrogen, and ultra-purified zero air for various analytical instruments. The unit prepares blood samples for headspace analysis in suspected DUI cases, using a heated autosampler and a gas chromatograph to determine blood alcohol levels. It also employs a Fourier-transform infrared spectrophotometer for the structural identification of organic compounds, verifying controlled substances through color tests. The unit further analyzes ignitable liquids in arson debris, using a gas chromatograph-mass spectrometer for compound analysis.

Mindmap

Keywords

💡Forensic Chemistry Unit

The Forensic Chemistry Unit is a specialized department within a forensic science laboratory that focuses on the analysis of physical evidence related to criminal investigations. In the context of the video, this unit handles a significant volume of narcotics cases and blood alcohol cases each year, playing a crucial role in determining whether crimes such as DUIs have been committed. The unit's work is integral to the legal process, as it provides scientific evidence that can be used in court.

💡Narcotics Cases

Narcotics cases refer to legal proceedings involving the illegal use, possession, or distribution of drugs. The video mentions that the forensic chemistry unit handles over 5,000 such cases annually, requiring the analysis of tens of thousands of items. This highlights the unit's critical role in the fight against drug-related crimes by providing scientific analysis to support law enforcement efforts.

💡Blood Alcohol Cases

Blood alcohol cases involve the determination of alcohol levels in a person's blood to ascertain if they were driving under the influence (DUI). The script specifies that the unit processes over 800 such cases each year. This involves using techniques like headspace analysis, where blood samples are heated to release alcohol vapors, which are then analyzed to determine the blood alcohol content.

💡Ignitable Liquids

Ignitable liquids are substances that can be used to start or accelerate fires, often in the context of arson investigations. The video explains that the forensic chemistry unit also performs analysis for ignitable liquids, assisting the Denver police and fire departments. This involves analyzing debris from potential arson scenes to identify any accelerants that may have been used.

💡Headspace Analysis

Headspace analysis is a technique used to determine the concentration of volatile compounds in a sample. As described in the script, blood samples are prepared for headspace analysis in suspected DUI cases. The blood is heated, forcing the alcohol into the air above the sample, from where it is collected and analyzed. This method is crucial for accurately measuring blood alcohol levels.

💡Gas Chromatograph

A gas chromatograph is an analytical instrument used to separate and analyze compounds that can be vaporized without decomposition. The script mentions that after the headspace analysis, the sample is injected into a gas chromatograph to determine the alcohol value of the blood sample. This instrument is essential for identifying and quantifying substances in forensic chemistry.

💡Infrared Spectrophotometer

An infrared spectrophotometer is a device that measures the interaction of infrared light with a sample, providing information about its chemical composition. The video describes the use of a 4ye transform infrared spectrophotometer for analyzing controlled substances, which can perform structural identification of relatively pure organic compounds within approximately 30 seconds.

💡Color Tests

Color tests are a series of chemical tests that produce color changes in response to the presence of specific substances. In the context of the video, these tests are used to verify controlled substances, with different color changes indicating the possible presence of narcotics like amphetamines or cocaine. The script provides examples of color changes that help identify the type of substance in a sample.

💡Arsen Debris

Arsen debris refers to the residue or remains that are left after a fire, which can be analyzed for evidence of arson. The script mentions that the forensic chemistry unit analyzes ignitable liquids in arson debris cases. This involves heating the debris to release volatile compounds, which are then absorbed and analyzed to determine if an accelerant was used to start the fire.

💡Mass Spectrometer

A mass spectrometer is an analytical instrument that identifies and quantifies chemicals by measuring the mass-to-charge ratio of ionized particles. The video script describes its use in analyzing ignitable liquids in arson debris as well as in controlled substance analysis. This instrument provides precise data that helps in identifying specific compounds present in a sample.

Highlights

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

The unit processes tens of thousands of items for narcotics analysis.

Over 800 blood alcohol cases are processed each year to determine DUIs.

Analysis of ignitable liquids and arson investigations is also performed.

The unit assists the Denver police and fire departments with state-of-the-art laboratory equipment.

Gas generators are used to produce gases for instrument operation.

Hydrogen is produced as a carrier and fuel gas.

Nitrogen serves as a carrier gas and for purging water from instrumentation.

Ultra-purified zero air is used in flame ionization detectors.

Vials of blood are prepared for headspace analysis in suspected DUI cases.

Alcohol in blood samples is analyzed by heating the blood to release volatile alcohol.

A heated headspace Auto sampler is used to automate sample processing.

Gas chromatograph is used to determine the alcohol value of blood samples.

Fourier Transform Infrared Spectrophotometer is used for structural identification of organic compounds.

Color tests are used to verify the presence of different narcotics.

Orange color in tests indicates the presence of amphetamine-like compounds.

Pink color after testing suggests the absence of cocaine.

Dark blue color indicates the presence of a secondary amine, suggesting methamphetamine.

The forensic chemistry unit also analyzes ignitable liquids in arson debris cases.

A carbon tab is used to absorb volatile compounds from heated samples.

Gas chromatograph Mass spectrometer is used for analyzing volatile compounds.