When run on a validated method, on an instrument that has properly qualified and certified as good for general use prior to testing unknowns, on a stable instrument, on an instrument that has proper and confirmed Quality Control (QC) immediately prior to use and with an experienced operator with no sampling or preparation error coupled […]
Toxicology versus solid drug dose examination for controlled substances
When we use GC-MS for forensic science purposes for controlled substance detection, we can basically divide the world into two camps. First, is the world of solid drug dose in pre-consumption form. The second is in the world post-consumption form analysis in a biological matrix (blood, urine, or oral fluid) which is otherwise known as […]
The importance of t0 in forensic chromatography
If you are bored and want to have a little fun, call up your local crime laboratory, ask for someone who preforms their chromatography (it doesn’t matter if it is liquid chromatography or gas chromatography). When you get that person ask them a simple question: What’s the t0 (pronounced “t subzero”) for your method that […]
Quality Control in GC-FID: Teaching the machine right from wrong
It is shocking but very true statement that most sophisticated instruments such as a Gas Chromatograph (GC) with various detectors whether it is a mass spectrometer (MS) or flame ionization detector (FID) when produced and manufactured are incapable of producing meaningful results “straight out of the box.” These machines have to be “taught” what it […]
Hemolysis in a blood sample when using headspace analysis by GC-FID
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 […]
Williams v. Illinois: The Confrontation Clause Rights in light of modern forensic science
On December 6, 2011, the Unites States Supreme Court heard argument in the case of Williams v. Illinois. The transcripts of the oral argument can is available on the Supreme Court of the United States website. Some information so you can understand the facts and the subsequent analysis that I offer: Summary of the Facts: […]
GC consumables and preventive maintenance
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
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
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 […]
Born on Date– Not Just for Beer But Gas Cylinders Too
Beer Born On Date Everyone wants to eat fresh food as opposed to stale food. No one wants to drink skunked beer. So, we have born-on dates on certain foods and foodstuff. This allows us to judge whether or not we want to accept it and drink/eat it. Carrier gas purity is a big issue […]
Emerging technology at the airport: Mass Spectrometry in the Hands of TSA
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 […]
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