Day 12

We arrived at the lab at 7:45 and left a 6PM. 

It was found that internal standard area counts for the closing CCV from last night’s run were greater than 25% of expected, but just barely. Evaluation of sample internal standard area counts revealed that area counts all met data quality objectives. Additionally, 8 compounds were above the +/- 25% expected recovery data quality objective. However, Kim Anderson (OSU) and I agreed that due to devotions from OSU’s Standard Operating Procedures (i.e. gas purity and detector deterioration) that it would be appropriate to widen the data quality objectives. At +/- 35% of expected, >90% of compounds in the CCV were within data quality objectives. We will proceed in this fashion. Thus, the first analytical batch of samples met project data quality objectives and are ready to be quantified for pesticides. Anna worked through one sample today due to many distractions (~ a rate of 1 sample/hr). 

In order to conserve the 100ppb calibration standard, which I used as a continuing calibration verification in last night’s run, I had Anna prepare 10mL of a 100ppb CCV for use in the analysis. I then compared the GC-ECD responses of the newly prepared CCV solution to the previously used 100ppb calibration standard and found that they were nearly identical except that the internal standard area counts were a bit higher in the news solution… near the ranges of the +20% expected level determined from calibration standards. Therefore,  I will open the internal standard area count data quality objectives to +/-50% as per OSU’s SOP. 

Anna and I also fussed with getting the instrument back in running condition after last night’s sequence; mainly trying to improve responses for a handful of pesticides. We tried a 1hr and a 2 hr instrument bake-out but saw minimal improvement. Discussion with Ted Haigh (OSU) revealed that he replaced liners after each analytical batch and that seemed to work perfectly. I will adopt this method. However, I will wash liners with acetone and hexane and reuse them because CERES does not have any 4mm injection port liners – the ones needed for this method!    

Some specific points:

1. We found that isodrin co-elutes with PCB100 on the front column… thus it cannot be quantified by CERES.
2. Due to myriad distractions, it took Anna much more time than necessary to analyze a sample.
3. The myriad distractions led to Anna making errors filling out chromatographic bench sheets… even while I was sitting with her.
4. I found that Marie and Adama did not truly understand how to report some of the information needed for sample extraction bench sheets. Specifically, they copied the sample extraction batch number verbatim from a bench sheet that I had helped prepare onto the bench sheet of a brand new batch of samples prepared on a completely different day. I explained this to Marie and had her explain back to me the definition of an extraction batch and how to appropriately label bench sheets.
5. I still find myself reminding CERES staff that verifying pipettes before use is absolutely necessary for this project and any other project that they are involved in.