Chromatography Quiz #18

xmas candiesChromatography Quiz #17 Results

We would like to congratulate our grand prize winners of our last newsletter’s Glyphosate chromatogram quiz: Tom Schneider from the Suffolk County Water Authority, Hossein Hajipour from Texas Department of State Health Services Environmental Division, Helene Lachance from Shur-Gain Nutreco, June Black from Pennsylvania Department of Environmental Protection, Narjes Ghafoori from LA County Environmental Toxicology Laboratory, Jason Yang from Ameritech, Joy Gottlieb from New Mexico Department of Health Scientific Lab Division, and Jim Balk from DHHS Public Health Environmental Laboratory!

They have each won and will shortly be receiving: The Christopher Elbow Artisanal Chocolates Holiday Collection!  This collection of chocolates features a festive assortment of flavors inspired by the holiday season.  Enjoy!

We would like to thank all of you for your submissions!

The correct answer for the troubleshooting chromatogram: We switched the reagents when running the Glyphosate chromatogram, putting the GA104/OPA/Thiofluor reagent first and the GA116/hypochlorite reagent second.  For Glyphosate analysis, the post-column reaction is two-stage. In the first stage, Glyphosate is oxidized by hypochlorite to Glycine. In the second stage, Glycine reacts with OPA and Thiofluor to produce a highly fluorescent isoindole. Without the first hypochlorite reaction, Glyphosate was unable to react and produce the fluorescent isoindole, and no peak appeared.  Since AMPA does not need the initial oxidation to react with OPA, we still see the AMPA peak.  And since oxidation reduces its fluorescent yield, we actually see a slightly larger than normal peak for AMPA.

Due to the typo on the last quiz, which originally gave the wrong reactor temperature, we understandably got a lot of responses indicating the problem was Reactor 1 temperature (prizes also awarded for this answer).  It made us curious – what does a Glyphosate chromatogram look like with a 100°C reactor?  How would it compare to the chromatogram we published?  So, we ran a couple of chromatograms, and here you can compare the two problems.

Original Troubleshooting Chromatogram (Switching Reagents):glyphosate troubleshooting chromatogram quiz 17

Comparison Bad Chromatogram (Reactor at 100°C):glyphosate chromatogram 2

Reference Chromatogram:glyphosate reference chromatogram quiz 17

We thought this was an interesting exercise.  Hopefully you did to!

Thank you!
Pickering Labs

Chromatography Quiz #18: Applications Puzzle!

Complete the Word Search Puzzle below and win a prize!  Simply email your answer as well as your full contact information to Rebecca at by February 1st, 2015 in order to win.  You will receive email confirmation that your submission has been received.  The answer to the puzzle and winner congratulations will be published in the next issue (to be anonymous, please notify Rebecca in submission).

You can download the pdf version of the Word Search Here: Quiz #18 Word Search

word search