Field Retrieval 3

CERES completed Field Retrieval 3 without a problem. CERES staff in attendance included Adama, Marie, Anna, Sokhna, Makhfousse, Cheikh, and Emmanuel. Emmanuel had been occupied with another project so hadn’t been able to join us previously; but now every CERES lab member has experienced field training with PSDs.

CERES staff appear very comfortable and capable working with the PSD in the field. Their retrievals are coordinated, cooperative and efficient. This was the strongest aspect by far of the training.

We observed the same fouling pattern as before: Site 1 the worst, and Site 3 the best with 4 and 2 very similar. This gives no indication of contaminant load, but may be useful in the context of additional information such as pH, total dissolved or solids or salinity. It does demonstrate, however, that performance/permeability reference compounds (PRCs) will be important for maintaining accurate and comparable data.

We also observed the same activities as before: washing clothes and dishes, bathing, fishing, household water collection and watering livestock.

We leave for Dakar Friday morning and will head directly to the lab to clean the PSD and clean glassware (likely with hot solvent) to begin the dialysis on Monday. We hope to have retrieval 3 data by the end of the training on October 26^th.

The Source of the Contamination

We have been analyzing various samples to determine the source of the contamination. It appears that the source is indeed dirty glassware. The round bottom flasks used in the dialysis appear to be the most significant contributor to the contamination.

The glassware sample is blue, while the blank is red.
The peaks on the glassware sample represent compounds
not removed during the cleaning procedure.
Other issues are present and noted.

After stepping through SOP 2110.03 entitled Laboratory Glassware Cleaning, some issues with CERES equipment became clear. The SOP requires baking the glassware at 400 °C, however, the CERES oven can only achieve 100 °C. Also, where rinses with 18 Mohm·cm water are required, CERES only has access to basic distilled water. The flasks are more difficult to clean than other glassware due to the narrow mouth and high relative volume, making these cleaning steps all the more important. However, all lab glassware is now suspect.

The GC-ECD combined with helium as a carrier gas provides levels of detection approximately two orders of magnitude greater than CERES could previously obtain. The levels of contamination were such that they would likely have been hidden in the higher former baseline. CERES’s increased analytical capabilities have exposed new issues, but the steps necessary to fix the situation should not be difficult. An oven capable of 400 °C will need to be obtained. This should not be prohibitively expensive and CERES has the counter space next to the other ovens. This oven should not be used for any purpose other than cleaning lab equipment.

As a result of this incident, the CERES/OSU split will not be immediately processed. An attempt will be made to clean glassware by different, solvent intensive, method and the PSD from Retrieval 3 will be extracted and analyzed.

To put this incident in perspective, brief commentary is necessary. CERES has quality equipment and staff, and the potential to deliver the required results. The increased analytical requirements of this project (and, inevitably, most if not all future work for pesticide analysis not related to this project) have pushed the limits of other points in the chain of analysis. Parts per million levels (CERES previous capabilities) will not suffice and the move to parts per billion capabilities exposed the weak spots that should be addressed.

Minor pieces of equipment are needed to increase performance. A hotter oven will help significantly, but one of the laboratory hoods should have the countertop covered in either high-grade (e.g. 316) stainless steel or replaceable Teflon paper with adhesive backing. The grout on the existing tile countertops is a high risk for harboring contamination. Additionally, high purity water (HPLC grade) would also help.

On another note, Bill and Hama will be joining us on the 3rd and final retrieval at Pont Gendarme today through Friday.