Day 7

Anna, Marie, Adama, and I were at the lab from 7:45AM to 6:30PM today.

I was on the GC-ECD instrument most of the day. I've concluded that the large peak that shows up in the chromatograms and maxes out the back detector is indeed the internal standard; it is present at the same magnitude in both calibration sets at all levels, it has the same Rt as the single component IS solution, and it's amplitude relative to the rest of the peaks present in the chromatograms is similar to what was seem when we ran these standards at OSU. Again, it appears to be a detector related issue where instrument response increases non-linearly with increasing instrument background.

Anna and the CERES staff completed the sample preparation of the second batch of PSDs. Included in this batch was a native over-spike that was introduced at the rotary evaporation step of the the sample preparation process. This will provide information on compounds specific losses that could be occurring at this step - a step that is conducted using lab apparatus that deviates from OSU's. The concentration of natives in the final extract should be ~100ppb. I will have them prepare one more of these today so that we have n = 2. I will also have them include extraction surrogates (TCMX and decachlorobiphenyl) with this replicate.

I racked up a sequence of singles to run on the GC-ECD through the evening; mainly compounds that have poor resolution with other compounds and key quality control residues. Additionally, the third batch of PSD dialysis was initiated and another batch of glassware is baking out.

Specific points:

1. CERES ran out of n-hexane today at the rotary evaporation step of sample processing. However, the vendor finally showed up ~1 hr later with the delivery of n-hexane. Supposedly Ann has been asking them for this shipment since before I arrived. We were also informed that this was the last batch of n-hexane in Senegal for unknown amount of time... they would not give me a straight answer. Is this the only vendor in Senegal? Anyways, doing a back of the envelope estimate, it appears that CERES has enough n-hexane to complete the preparation of PSDs.
2. Dakar power went out today for over an hour and the generator was turned off due to some undisclosed system failure. At this point, all instruments were cycled off and extractions were delayed until the power came back on and the generator had been evaluated by CERES' generator contractor. 
3. CERES staff are continuing to become more comfortable in the lab. I have instructed them to perform dialysis with 2 people so that 3rd person could take a rest (the average temperature of the prep lab during this part of the year is 30 C - 86 F and the fume hoods perform poorly).
4. CERES staff have continued filling out paperwork thoroughly by making it a top priority.        
5. Analysis of calibration standards revealed that there are more peaks in the chromatograms than expected; some are quite significant. Additionally, the peaks are present in both calibration sets and to the same degree. Running the singles will help with compound ID.