Week 61 Forensic Science Geek of the Week is Announced

The Forensic Science Geek of the Week

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The week 71 “www.TheTruthAboutForensicScience.com Forensic Science Geek of the Week” honors goes to: William Herringer, Esquire

Attorney William Herringer is in the middle getting ready to make a direct liquid injection with his lab partners at the ACS hands-on Forensic Chromatography V class

About our winner according to his website:

Attorney William Herringer is a trial litigator who is located in Durango, CO. He is a partner in Greenberg & Herringer, LLC. Greenberg & Herringer LLC, Durango area attorneys at law, practice in both criminal defense and family law. They can handle cases before federal, state and tribal courts and can provide legal help to those in La Plata, Montezuma, Archuleta, San Juan, San Miguel, Ouray and Montrose Counties. They offer counseling for criminal matters including felonies, drug, DUI/DWAI and domestic violence. They will handle family law cases including divorce, child custody, alimony & support and mediation.He defends motorists who are accused of a DUI. Herringer also is a member of the National College for DUI Defense Incorporated. He most recently completed the 5 day intensive hands-on ACS Forensic Chromatography Course held at Axion Analytical Laboratories, Inc. in Chicago Illinois.

Congratulations to our Forensic Science Geek of the Week winner!

OFFICIAL QUESTION:

: The Forensic Science Geek of the Week Challenge

1. What specific technique is depicted in this photo?

2. Explain it.

3. What are its limitations?

Our Geek of the Week answered:

Answer to Week 61 Question

1. What specific technique is depicted in this photo?

Time of Flight Mass Spectrometer

2. Explain it.

A time-of-flight mass spectrometer uses the differences in transit time through a drift region to separate ions of different masses. The ions from the ion source are accelerated by an electric field pulse. The accelerated particles then pass into a field-free drift tube that is about a meter in length.

The essential principle of time-of-flight mass spectrometry is that all ions are accelerated to the same kinetic energy. Their velocities are inversely proportional to the square roots of their masses. The lighter ions of high velocity arrive at the detector earlier than the heavier ions of low velocity.

3. What are its limitations?

-Requires pulsed ionization method or ion beam switching (duty cycle is a factor)
-Fast digitizers used in TOF can have limited dynamic range
-Limited precursor-ion selectivity for most MS/MS experiments

All answers (including identifying the picture) obtained using Google and cut and pasted into this post. Don’t know if that is cheating, but it was the only way I was going to get the answer.

[BLOGGER’S NOTE: What a great answer. Thank you for participating. Congratulations on being our Geek of the Week. Just to further amplify. Time of Flight Mass Spectrometry (TOF-MS) is very good at determining the molecular ion that then can be used to deduce what possible compound it could be. As it is simply like a proverbial foot race to the detector, there is not going to be a lot of mass spectral information on the mass spectra produced. So, in terms of positive and conclusive qualitative analysis, it is not as useful as QqQ or NMR. It is very fast analysis. It is a high throughput device. Theoretically, there should be no limit to the molecular weight/mass that can be examined. It has a very tight and limited linear dynamic range. It should not be a first choice for quantitative analysis.]

The Hall of Fame for the www.TheTruthAboutForensicScience.com Forensic Science Geek of the Week:

Week 1: Chuck Ramsay, Esquire

Week 2: Rick McIndoe, PhD

Week 3: Christine Funk, Esquire

Week 4: Stephen Daniels

Week 5: Stephen Daniels

Week 6: Richard Middlebrook, Esquire

Week 7: Christine Funk, Esquire

Week 8: Ron Moore, B.S., J.D.

Week 9: Ron Moore, B.S., J.D.

Week 10: Kelly Case, Esquire and Michael Dye, Esquire

Week 11: Brian Manchester, Esquire