Day 14 - Challenging times

I was at CERES from 8:15AM to 4PM; traffic got us off to a later start than usual.

I immediately cooled down the instrument in order to perform the previously discussed injection port maintenance and took steps to equilabrate the instrument. However, equilibration was not able to be achieved. The detector signal was noisy (~ +/- 2-8 Hz), it wandered (~+/- 300 Hz), and displayed random spikes (~ >100Hz). Inspection of chromatograms from last night's run revealed the same pattern. Anna and I checked the system for leaks, verified that gases were flowing, replaced injection port O-rings and septa, and tightened column nuts - but with no improvement. Interestingly, symptoms were amplified whenever the column oven was heated to operating temperature and were reduced when at room temperature. A temporal look back through chromatographic data generated over the course of my time at CERES revealed that these symptoms have been present all along, but have steadily escalated to the current state. Consultation with Glenn Wilson (senior research faculty - OSU) and Kim Anderson (OSU) suggested that these symptoms were different from typical instrument issues that OSU staff have experienced. Just as an example, OSU's GC-ECD resting baseline fluctuates +/- 0.25-0.5 Hz. We suspect that there might be something going on in/around the portion of the instrument where the columns connect to the detector. I will evaluate this portion of the instrument on Monday. Unfortunately, last night's run will not be useable for quantitation due to the chromatographic blemishes described above and it's not clear how long it will take to right the instrument. 

On a high note, Anna completed instrumental analysis of the first batch of PSDs, all required bench sheets, and saved the data in Excel files. YES! I'm also happy to report that her confidence improved substantially over the course of the analysis. Furthermore, Adama and Marie completed the last batch of PSD extractions (acetone arrived Thursday evening); all samples have now been extracted. Similarly to Anna, their attention to detail regarding thorough completion of bench sheets has improved markedly compared to the field sampling bench sheets that were received by OSU.