Quiz #46 – Peaking at the wrong time
In this Glyphosate chromatogram per EPA 547 (link to method abstract), you will see Only the metabolite AMPA eluting around 15 min. What is contributing to the loss of Glyphosate?
Submit your answers to rsmith@pickeringlabs.com by May 30, 2025.
Pickering Standard: 1700-0080 Glyphosate Test Mixture, 2.5 µg/mL, 10 µL injection
Pickering Column: 1954150 Cation-exchange Column for Glyphosate analysis, 4 x 150 mm
Normal Operating Conditions: (for reference only, condition changes may be reflected in chromatogram)
Column Temperature: 55 °C
Flow rate: 0.4 mL/min
Eluent Gradient:
|
TIME |
K200 |
RG019 |
|
0 |
100 |
0 |
|
15 |
100 |
0 |
|
15.1 |
0 |
100 |
|
17 |
0 |
100 |
|
17.1 |
100 |
0 |
|
27 |
100 |
0 |
Post-column conditions:
Reagent 1: Oxidizing reagent – 100 uL of 5% Sodium Hypochlorite in 950 mL of GA116
Reagent 2: 100 mg of OPA, 2 g Thiofluor™ in 950 mL of GA104
Reactor 1: 36 °C, 0.5 mL
Reactor 2: ambient. 0.1 mL
Reagent flow rates: 0.3 mL/min
Detection: Fluorometer ex 330 nm, em 465 nm
Troubleshooting Chromatogram:
Reference Chromatogram:
Announcing the winners of our previous quiz, Chromatography Quiz #45 – Amino Acids Rising Baseline
Pickering Laboratories would like to congratulate the winners for our previous newsletter’s Chromatography Quiz #45: Josiah Hakala from Minnesota Department of Health, Thomas Schneider from SCWA and Narjes Ghafoori from Los Angeles County Public Health Laboratory.
Our winners will shortly be receiving: a remote-controlled drone, complete with 4k camera!
Congratulations to our quiz winners! Thank you all for your submissions!
Chromatography Quiz #45 Solution:
For this problem, we had to review the Onyx pump pressure trace.
We did find a loose tubing on the cap resulting in air being sucked into the pump. The air is initially pushed out at the beginning of the run. You can see the pressure coming up very slowly. Once the reagent is delivered properly, you have a good baseline.
Below you will find the pressure trace once the tubing was secured.
The method details can be found on our website (check out our amino acids brochure).
