Day 17 - GC-ECD and purifiers

I arrived at the lab at 7:50AM and left around 4:45PM.

I investigated more into the gases that supply all CERES GC instruments (ECD and mass spectrometers). The purity of nitrogen and helium that CERES purchase is 99.995%. Agilent, the manufacturer of the instrument involved in this study, recommends using gases of >99.9995% purity with the GC-ECD. Gas specification sheets requested from CERES’ supplier (Air Liquide) report that nitrogen and helium gases at the grade that CERES purchase have <5ppm of both molecular oxygen and molecular water (i.e. moisture). Assuming the worst case scenario, that gases being supplied to instruments have 5ppm oxygen and water, EACH HIGH PRESSURE GAS TANK at 10m^3 should contain ~ 35 L of oxygen and ~ 50g of moisture (i.e. water). 

CERES currently has two nitrogen gas purifiers on their 1/8” gas lines: 1) an Agilent GMT-2HP moisture trap and 2) an Agilent Big Universal oxygen, moisture, and hydrocarbon combo-trap. The GMT-2HP and Big Universal moisture traps have moisture capacities of 20 g and 46 g respectively. They have been in place since Lucas Quarles’ (OSU) training session in 2009 and through > 5 tanks of nitrogen/year since then.  Additionally, I did some reading on different types of gas purification traps and learned about a type called “indicating traps”. This type of trap contains a band of reactive particles that turn colorful when in the presence of the gas they’re supposed to filter. The Agilent GMT-2HP moisture trap is an indicating trap and it currently displays a bright blue bland (See picture below). In regards to moisture, I conclude that both traps have exceeded their capacities and are not purifying nitrogen for moisture. The Agilent Big Universal trap has an oxygen capacity of 1.07L. Considering that EACH NITROGEN TANK maximally has 35L of oxygen, I’m confident that the trap’s capacity was also reached a very, veRY, VERY long time ago and that this trap is not purifying CERES' nitrogen of contaminant oxygen.

 Agilent GMT-2HP moisture indicator trap

 

Big Universal oxygen, moisture, and hydrocarbon combo-trap - Nitrogen Specific

On the helium line, CERES currently has a single helium specific Agilent Big Universal oxygen, moisture, and hydrocarbon combo-trap with the same capacities described earlier for the nitrogen version of the purifier. CERES helium has <5ppm of oxygen and moisture. Considering the argument provided above and that the purifier was also installed during Lucas Quarles’ (OSU) training session, I’m confident that this purifier also reached capacity a long time ago. In summary, CERES is not currently set up to deliver the purity of gases needed to effectively run the GC-ECD in a reproducible manner for this project or any other for that matter. Additionally, they have developed conditions that most surely have damaged internal components of the GC-ECD instrument, including but not limited to the analytical columns and the electron capture detector. 

 Big Universal oxygen, moisture, and hydrocarbon combo-trap - Helium Specific

The GC-ECD technician  from Technical House, mentioned yesterday, arrived around 3PM. He worked on the instrument detector for ~ 15 minutes and concluded that gas purity in combination with ineffective gas purification led to the current state of the ECD. He will be back tomorrow to work on the instrument. However, I was unable to decipher exactly what he’d be working on. Furthermore, Anna called around to local industries looking for gas purifiers that CERES could grab in a timely manner. The search was not successful and frankly I don’t think it wise for the lab to rush through this step. In contrast, I recommend that CERES should develop a well thought-out strategy for consistently maintaining laboratory instruments at a degree capable of conducting trace chemical analysis. 

Specific points:

1. CERES should investigate other high pressure gas suppliers to evaluate options and compare prices
2. CERES needs to purchase gas purifiers capable of meeting instrument needs relative to the purity of purchased gases. They are generally <$300 each and would save on laboratory down time, column replacement, detector degradation, equipment replacement, and service appointments with contractors. They should also have extra purifiers on hand for quick replacement. Achieving this objective would increase CERES workflow substantially across ALL projects.  
3.  Many of the concepts that I have discussed with CERES personnel seem to be familiar, but they do not carry them autonomously. CERES needs more training on the basics of instrument set-up and maintenance – specifically the “WHY THIS IS IMPORTANT” portion of that lesson.
4. CERES currently has their indicator traps positioned before their high capacity purification filter. This defeats the purpose of the indicating trap – to indicate when contaminant break through has occurred. CERES should plumb indicating traps after high capacity traps.
5. CERES have several extra traps, but they have been stored ineffectively and are suspect for contamination – for instance open to the ambient environment (see below and notice the uncapped ends of connections and tubing). CERES should store ALL non-used traps as per manufacturer recommendations and sealed from the ambient environment.