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Looking for Ethanol Metabolites and Barbiturates in Urine? Get the Fast and Sensitive ‘Two Bird, One Stone’ Method

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Alcohol is legal and widely available, but it is an intoxicating and addictive substance that can have harmful effects on the human mind and body.

It reduces inhibitions and distorts judgment and rational decision making, making it the number one cause of criminal behavior. And then there is the impact on health; alcohol-use disorders are common. There is an evident link between drinking and premature death, cancer and cardiovascular problems, in fact, this study found 23 health outcomes in total.

Putting the death toll into context, six people die every day in the United States alone due to alcohol poisoning, making alcohol the third leading preventable cause of death (after tobacco and poor lifestyle). In addition, eight people die every day in traffic accidents caused by alcohol-impaired driving and 86 percent of homicides are committed by individuals under the influence.

Are There Other Substances in The Cocktail?

Alcohol is easy to obtain in most countries and abuse is prevalent. But alcohol doesn’t always act alone.

There are a wide range of synthetic drugs that exaggerate and complicate the consequences of abuse. Rampant in the 1970s, but still very much in use today, are barbiturates. They are addictive and an overdose can be fatal, as was the case for many of our icons, such as Marylyn Monroe, Judy Garland, and Jimi Hendrix. What’s more, they become incredibly dangerous when combined with other depressants such as alcohol.

Forensic toxicologists need to understand more about how ethanol and barbiturates are broken down by the body and into which metabolites. They also need dependable routine screening methods to produce results that stand up in court, with the throughput to keep up with mounting criminal charges, civil lawsuits and post-mortem toxicology related to alcohol and/or barbiturate use.

Sensitive Single-Sample-Prep, Single-Injection Forensic Analysis

While most analytes in forensic applications analyze well with positive ionization, there are analytes that show better ionization efficiency with negative ionization. This is the case for ethanol metabolites such as ethyl glucuronide (ETG), ethyl sulfate (ETS), and barbiturates such as amobarbital, butabarbital, butalbital, pentobarbital, phenobarbital, and secobarbital.

This is where liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) plays to its strengths as a forensic analytical tool.

When analyzing a comprehensive forensic analytical panel, detection of urinary barbiturates is done in negative ionization mode, and the majority of other compound classes are detected in positive ionization mode, using polarity switching. But for ethanol and barbiturate analysis, a two-sample-preparation/two-injection approach is typically inevitable.

In the tech note ‘Fast and Simultaneous Analysis of Ethanol Metabolites and Barbiturates Using the QTRAP® 4500 LC-MS/MS System’, we have developed a single-sample-preparation/single-injection method. With sample prep based on a simple “dilute and shoot” methodology without hydrolysis, the method has a total runtime of just 5 minutes. It shows good sensitivity and is very robust. More than 800 continuous injections of human urine samples were performed on a single LC column with no evident deterioration in performance.

Download the SCIEX Forensics Compendium 2018 to see this method in its full glory, along with recent advancements developed by the forensics team and a view on where LC-MS/MS technology could take forensics in the future.

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