Chemistry - Page 4 of 7 | The Truth About Forensic Science

More on the forensics of synthetic drugs: synthetic cannabinoids and synthetic cathinones

On December 29, 2011, in Chemistry, Solid Drug Dose, by Justin J. McShane

The forensic world continues to grapple with the forensics of identifying synthetic drugs and their pharmacological and analytical chemistry characteristics. As we have written before just because there may be laws on the books or emergency or permanent regulations outlawing certain drugs and their analogues doesn’t mean that they can actually prove scientifically that the […]

Hemolysis in a blood sample when using headspace analysis by GC-FID

On December 21, 2011, in Chemistry, Equipment, GC-FID & GC/MS, Phlebotomy, by Justin J. McShane

Hemolysis is a particular problem in the proper quantification of EtOH in a blood sample. First let’s define what it is: What does it look like? Red blood cells without (left and middle) and with (right) hemolysis. If as little as 0.5% of the red blood cells are hemolyzed, the released hemoglobin will cause the […]

GC consumables and preventive maintenance

On December 6, 2011, in Chemistry, GC-FID & GC/MS, by Justin J. McShane

Lots of prosecutors and police scientists like to present the Gas Chromatograph (GC) and its results as totally infallible, not subject to interpretation, and never wrong. While GC technology is good (in fact if the analysis is conducted on a stable and properly maintained and installed instrument using a validated method with a well-trained and […]

How the GC-FID arrives at a quantitative result: Auto-integration versus Manual Integration

On December 1, 2011, in Chemistry, Equipment, GC-FID & GC/MS, In The Courtroom, Laboratory Procedure, Metrology, Standards, by Justin J. McShane

A frequently asked question on the listservs that I belong to basically asks the following question: In GC-FID use to quantify Blood Alcohol Content where EtOH is the target analyte, how does the machine arrive at the reported number? The machine is called a Gas Chromatograph with a Flame Ionization Detector (GC-FID). Typically the sample […]

The Coalition against Coelution

On November 17, 2011, in Chemistry, GC-FID & GC/MS, by Justin J. McShane

I saw this idea on the Restek Blog and thought it was quite funny. So I took it and slightly tweaked it. I wanted to share it with you… Move over Occupy (fill in the blank movement)… I’m helping to start a new a new movement “The CAC” or The Coalition Against Coelution stands for […]

The Problem of Modern Forensic Science: Novices can become experts at the push of a button

On September 22, 2011, in Chemistry, Equipment, Ethics, Ethics: Scientist, Identification, In The Courtroom, Lab Scandals & Failures, Laboratory Procedure, by Justin J. McShane

I have lamented before about the horrible state of affairs that has developed in modern forensic science and in particular instrumentation. As an industry, the machine manufacturers seek to automate and make these processes so simple that they no longer require true understanding of the underlying science or the process that makes the machine do […]

Emerging technology at the airport: Mass Spectrometry in the Hands of TSA

On September 20, 2011, in Chemistry, Equipment, GC-FID & GC/MS, by Justin J. McShane

GE EntryScan is a type of newer technology EntryScan is the result of a successful five-year partnership between GE, the Pennsylvania State University Gas Dynamics Laboratory and the FAA/TSA. This research effort was based on the concept of understanding the natural airflow around the human body. In April 2003, the TSA confirmed that the EntryScan […]

Standards, Controls, Calibrators, and Verifiers, Oh my…

On September 6, 2011, in Chemistry, Equipment, Ethics, Ethics: Scientist, GC-FID & GC/MS, Identification, In The Courtroom, Laboratory Procedure, Metrology, Standards, by Justin J. McShane

Lions and Tigers and Bears… Verifiers, Calibrators and Controls… Oh my! Sometimes a criminal defense attorney can at times feel like Dorothy in the Wizard of Oz in that we are transported from the relative safety of home (the courtroom) to the weird world of Oz (the laboratory). There are unusual and often times conflicting […]

Why single column Gas Chromatography-Flame Ionization Detector analysis is not forensically or scientifically acceptable

On September 1, 2011, in Chemistry, Equipment, GC-FID & GC/MS, Identification, In The Courtroom, Laboratory Procedure, Metrology, by Justin J. McShane

There is a large difference between a single column analysis and a dual column analysis when it comes to the ability to most correctly identify and quantitate an unknown in the scientific world. In forensic science, we are constantly testing unknowns. What is meant by this is that we have a sample that is seized […]

Police Science: Re-purposing of Capilliary Columns for Drugs of Abuse testing

On August 30, 2011, in Chemistry, Equipment, Ethics, Ethics: Scientist, GC-FID & GC/MS, Identification, In The Courtroom, Laboratory Procedure, Solid Drug Dose, by Justin J. McShane

As I have written before a lot of forensic science is really legitimate analytical chemistry that is re-purposed for the courtroom, but without proper scientific method validation before deploying it into this new purpose. This re-purposing of legitimate techniques and employing them without examining the true validity of doing so is not scientific. I call […]

A Gas Chromatoagraph or Liquid Chromatograph is not like a calculator

On August 23, 2011, in Chemistry, Equipment, Ethics, Ethics: Scientist, GC-FID & GC/MS, Identification, Laboratory Procedure, by Justin J. McShane

I am fond of pointing out that a Gas Chromatograph (GC) and a Liquid Chromatograph (LC) are not like a simple calculator where anyone walking up to a calculator regardless if it is a 2 year old or a PhD in mathematics who keys in 2+2, the result will always be 4, it requires interpretation […]

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