Chromatography Quiz No. 6

Chromatography Quiz #5 Results
We would like to congratulate the grand prize winner of our last newsletter’s Carbamate Chromatography Quiz: June Black from the Pennsylvania Department of Environmental Protection! 
She has won, and will shortly be receiving, an extensive California Wines Gift Basket!  Additionally, for this quiz all of our participants will each be receiving a $25 gift card from Bevmo! Again, we would like to thank you all for your submissions.  
The correct answer for the modified Carbamate chromatogram: The system was improperly equilibrated at a higher percentage of methanol (50:50 Water:Methanol) prior to injection.  After injection, the gradient program began with normal starting conditions (85:15 Water:Methanol). For the less retained compounds, the improper conditions on the column at the time of injection will push them through faster, causing coelutions.  Longer retained compounds are less affected by starting conditions of the column, and impacted more by the gradient (which was correct) so you see less of an effect on the later part of the chromatogram. 
Thank you! 
Pickering Labs
Chromatography Quiz #6:
Identify the error made when running the Aflatoxins chromatogram below and win a prize!  Simply email your answer as well as your full contact information to Rebecca at by March 31st in order to win.  You will receive email confirmation that your submission has been received.  The troubleshooting answer and winner congratulations will be published in the next issue (to be anonymous, please notify Rebecca in submission). 

Aflatoxins Analysis by AOAC Official Method 2005.08
LCTech Standard: 0.25 ng B2, G2 and 1.0 ng B1, G1 injected on-column in both chromatograms
LCTech Analytical Column: 150 x 4.6 mm; RP C18 (P/N 10522)
LCTech Guard Column: 8 x 4 mm (P/N 10523; holder P/N 10750)
Normal Operating Conditions: (for reference only, condition changes may be reflected in chromatogram)
Column Temperature: 36 °C
Mobile Phase: Water/methanol/acetonitrile 55/30/15
Isocratic Flow rate: 1.3 mL/min
Post-column conditions:
Photochemical Derivatization: 254nm UV low pressure lamp (LCTech UVE derivatizer, Pickering P/N 1100-3347)
Detection: Fluorometer:  ex 365 nm, em 460 nm