Day 8 - Friday

We arrived at the CERES laboratory at 8AM and left at 4:30PM.

At the GC-ECD instrument - Single component pesticide solutions run last night were used to identify 17ms and XLB peaks today. Adama and Marie received training on how to use Chemstation to identify analytes. Each independently identified 4 compounds by comparing calibration standard to single component solution chromatograms. In all, ~ 35% of the project analyte list was run as singles. This information was used to update calibration table retention times for the 17ms; the XLB portion of the cal table will be updated on Monday. PRC compounds were identified through comparison of CERES chromatograms to OSU generated chromatograms. This is the best we can do because we do not have singles of these compounds at CERES. Interestingly, chromatograms of standards generated at CERES display many more peaks than the OSU generated chromatograms. In fact some of the “extra peaks” match the retention times of impurities in in Ted's 2011 single component solutions. Could these “extra peaks” in cal standards be related to the long transport time and high ambient temperature experienced during shipment from OSU to CERES? It’s plausible.

  

In the sample preparation lab – the CERES team continued with PSD extractions and completed a third batch. I worked with Marie to improve her sample preparation technique; specifically I demonstrated how to hold extraction jars when decanting extracts into round bottom flasks so as to minimize contamination and spills. Another batch of glassware has been prepared for bake out over the weekend. Anna and I plan on meeting on Sunday to initiate the extraction of a 4^th batch of PSDs so that come Monday, the lab can continue extracting. CERES staff continue to fill out benchsheets thoroughly and completely. When not working on our project, staff continued to work on validating a QuEChERS method for the analysis of pesticides in agricultural products.

I’m still working out how exactly to proceed with sample analysis considering the limitations of the back detector (i.e. how it slams the internal standard signal through the top of the detector).