Category Archives: AMPA

Chromatography Quiz #27: Only AMPA

Chromatography Quiz #26: Shifting Retention Times – Carbamates — Results

Pickering Labs would like to congratulate the winners of our last newsletter’s Shifting Retention Times–Carbamates Quiz: David Green from Pepperdine University, Jeff Fan from Cumberland Valley Analytical Services, Karissa Scroggins from North Coast Laboratories, Jim Balk from Nebraska DHHS Public Health Environmental Laboratory, Narjes Ghafoori from LA County Agricultural Commissioner Weights & Measure Environmental Toxicology Lab, Tom Schneider from Suffolk County Water Authority, and Ms. Widchuda Meeim from Thailand Bureau of Quality Control of Livestock Products.

They have each won and will shortly receive a Williams Sonoma BBQ Tools Set! Included in a stainless-steel case for easy storage, these sleek grilling tools are perfect for those upcoming summer cookouts!

Congrats to our quiz winners and happy grilling!

Thank you all for your submissions! 

The correct answer to the Sifting Retention Times – Carbamate Quiz:

Leaking proportioning valve. The leaking proportioning valve improperly mixed the method gradient and didn’t have enough methanol which caused the analytes to elute late.

Chromatography Quiz #27: Only AMPA

What is causing the bad chromatography in the example below?  Simply email your answer as well as your full contact information to Rebecca at by September 1, 2017 in order to win.  You will receive email confirmation that your submission has been received.  The answer to the quiz and winner congratulations will be published in the next issue (to be anonymous, please notify Rebecca in submission). 

Glyphosate Analysis – Only AMPA

Pinnacle or Vector PCX post-column instrument is being used, in a traditional HPLC setup as recommended by Pickering Laboratories. The quiz question: what is causing Glyphosate to disappear?  

Post-column conditions for carbamates analysis:

Reagent 1: GA116
Reagent 2: o-Phthalaldehyde and Thiofluor in GA104
Reactor: 36 °C, 0.5 mL
Reagent flow rate: 0.3 mL/min
Injection volume: 10uL

FLD Settings:

λex 330 nm
λem 465 nm

HPLC Flowrate: 0.4 mL/min
Column Temperature: 55°C


Good Chromatogram

Glyphosate Test Mix, 2.5ppm, 10µl Injection

Bad Chromatogram only shows AMPA peak. No Glyphosate peak can be detected.

Glyphosate Test Mix, 2.5ppm, 10µl Injection