In a series of posts, we are going to talk about Mass Spectrometry. Introduction-The different configurations and the Electron Impact process What types of mass analyzers are there? What type of detectors are there? What types of analysis can be done? How do you read the output? How do they come to a qualitative measure […]
Mass Spectroscopy for Lawyers Part 5: How to read the output from the GC-MS
In a series of posts, we are going to talk about Mass Spectrometry. Introduction-The different configurations and the Electron Impact process What types of mass analyzers are there? What type of detectors are there? What types of analysis can be done? How do you read the output? How do they come to a qualitative measure […]
Mass Spectroscopy for Lawyers Part 4: What types of analysis can be done?
In a series of posts, we are going to talk about Mass Spectrometry. Introduction-The different configurations and the Electron Impact process What types of mass analyzers are there? What type of detectors are there? What types of analysis can be done? How do you read the output? How do they come to a qualitative measure […]
Mass Spectroscopy for Lawyers Part 3: What types of detectors are there?
In a series of posts, we are going to talk about Mass Spectrometry. Introduction-The different configurations and the Electron Impact process What types of mass analyzers are there? What type of detectors are there? What types of analysis can be done? How do you read the output? How do they come to a qualitative measure […]
Mass Spectroscopy for Lawyers Part 2: What types of mass analyzers are there?
In a series of posts, we are going to talk about Mass Spectrometry. Introduction-The different configurations and the Electron Impact process What types of mass analyzers are there? What type of detectors are there? What types of analysis can be done? How do you read the output? How do they come to a qualitative measure […]
Mass Spectroscopy for Lawyers Part 1: Introduction
In a series of posts, we are going to talk about Mass Spectrometry. Introduction-The different configurations and the Electron Impact process What types of mass analyzers are there? What type of detectors are there? What types of analysis can be done? How do you read the output? How do they come to a qualitative measure […]
Why doesn’t your state crime laboratory use AMDIS?
I have written about chromatography, gas chromatography (GC) and even gas chromatography with mass spectrometry (GC-MS). Here they are (in no particular order): GC-MS is not perfect: The case study of methamphetamine Why do I see two peaks on my EtOH analysis using HS-GC-FID? What is the difference between HS-GC-FID and GC-MS? Drugs of Abuse (DOA) […]
Why do I see two peaks on my EtOH analysis using HS-GC-FID?
Why do I see two peaks on my EtOH analysis using HS-GC-FID? This is a frequent question asked by criminal defense lawyers. Typically in the analysis of an accused’s motorist’s blood for EtOH composition (his or her Blood Alcohol Content) by way of Headspace Gas Chromatography with Flame Ionization Detector (HS-GC-FID) we will see two […]
Retesting Blood Alcohol Results
Sometimes, one of the scariest tests in the forensic science world are the more “routine” ones, such as Blood Alcohol analysis (meaning EtOH). There are such high demands in terms of throughput and such little real training in analytical chemistry in performing the assay given to the analysts that the potential for error is rather […]
What is the difference between HS-GC-FID and GC-MS?
First let’s remove the short hand and really write out what we are doing typically. For blood analysis for EtOH, its proper technical name is Isothermal Static Headspace Gas Chromatography using Wall Coated Open Tubular Capillary Columns with Flame Ionization Detector. We just short name it to HS-GC-FID. The technique is made up of distinct […]
Fool’s Gold or Real Gold? HS-GC-FID is it specific or selective or neither?
So many times, Headspace Gas Chromatography Flame Ionization Detector (HS-GC-FID) is described by government expert witnesses as the “gold standard” in forensics. This trite phrase is very misleading. HS-GC-FID analysis is a very good technique when compared to other assays, but it is not infallible and it is not even the best chromatographic method available […]
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